TY - JOUR A1 - Pinomaa, T. A1 - Lindroos, M. A1 - Jreidini, P. A1 - Haapalehto, M. A1 - Ammar, K. A1 - Wang, Lei A1 - Forest, S. A1 - Provatas, N. A1 - Laukkanen, A. T1 - Multiscale analysis of crystalline defect formation in rapid solidification of pure aluminium and aluminium-copper alloys N2 - Rapid solidification leads to unique microstructural features, where a less studied topic is the formation of various crystalline defects, including high dislocation densities, as well as gradients and splitting of the crystalline orientation. As these defects critically affect the material’s mechanical properties and performance features, it is important to understand the defect formation mechanisms, and how they depend on the solidification conditions and alloying. To illuminate the formation mechanisms of the rapid solidification induced crystalline defects, we conduct a multiscale modelling analysis consisting of bond-order potential-based molecular dynamics (MD), phase field crystal-based amplitude expansion simulations, and sequentially coupled phase field–crystal plasticity simulations. The resulting dislocation densities are quantified and compared to past experiments. The atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models, and the framework adds mechanistic insights arising from the multiscale analysis. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’. KW - Rapid solidification KW - Crystalline defects KW - Molecular dynamics KW - Phase field crystal KW - Phase field method KW - Crystal plasticity PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542156 DO - https://doi.org/10.1098/rsta.2020.0319 SN - 1364-503X VL - 380 IS - 2217 SP - 1 EP - 20 PB - Royal Society CY - London AN - OPUS4-54215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, A. A1 - Kranzmann, Axel T1 - Understanding the Anomalous Corrosion Behaviour of 17% Chromium Martensitic Stainless Steel in Laboratory CCS-Environment—A Descriptive Approach N2 - To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 ◦C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment. KW - Corrosion KW - Steel KW - High alloyed steel KW - Corrosion mechanism KW - CCS PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545700 DO - https://doi.org/10.3390/cleantechnol4020014 VL - 4 IS - 2 SP - 239 EP - 257 PB - MDPI AN - OPUS4-54570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, J. A1 - Farris, L. A1 - Nolze, Gert A1 - Reinsch, Stefan A1 - Cios, G. A1 - Tokarski, T. A1 - Thompson, S. T1 - Microstructure evolution in Inconel 718 produced by powder bed fusion additive manufacturing N2 - Inconel 718 is a precipitation strengthened, nickel-based super alloy of interest for the Additive Manufacturing (AM) of low volume, complex parts to reduce production time and cost compared to conventional subtractive processes. The AM process involves repeated rapid melting, solidification and reheating, which exposes the material to non-equilibrium conditions that affect elemental segregation and the subsequent formation of solidification phases, either beneficial or detrimental. These variations are difficult to characterize due to the small length scale within the micron sized melt pool. To understand how the non-equilibrium conditions affect the initial solidification phases and their critical temperatures, a multi-length scale, multi modal approach has been taken to evaluate various methods for identifying the initial phases formed in the as-built Inconel 718 produced by laser-powder bed fusion (L-PBF) additive manufacturing (AM). Using a range of characterization tools from the bulk differential thermal analysis (DTA) and x-ray diffraction (XRD) to spatially resolved images using a variety of electron microscopy tools, a better understanding is obtained of how these minor phases can be properly identified regarding the amount and size, morphology and distribution. Using the most promising characterization techniques for investigation of the as-built specimens, those techniques were used to evaluate the specimens after various heat treatments. During the sequence of heat treatments, the initial as-built dendritic structures recrystallized into well-defined grains whose size was dependent on the temperature. Although the resulting strength was similar in all heat treated specimens, the elongation increased as the grain size was refined due to differences in the precipitated phase distribution and morphology. KW - Metal additive manufacturing KW - Inconel 718 KW - Heat treatment KW - Grain boundary precipitates KW - Laves phase PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542758 DO - https://doi.org/10.3390/jmmp6010020 SN - 2504-4494 VL - 6 IS - 1 SP - 1 EP - 20 PB - MDPI CY - Basel AN - OPUS4-54275 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rütters, H. A1 - Fischer, S. A1 - Le, Quynh Hoa A1 - Bettge, Dirk A1 - Bäßler, Ralph A1 - Maßmann, J. A1 - Ostertag-Henning, C. A1 - Wolf, J. L. A1 - Pumpa, M. A1 - Lubenau, U. A1 - Knauer, S. A1 - Jaeger, P. A1 - Neumann, A. A1 - Svensson, K. A1 - Pöllmann, H. A1 - Lempp, C. A1 - Menezes, F. F. A1 - Hagemann, B. T1 - Towards defining reasonable minimum composition thresholds – Impacts of variable CO2 stream compositions on transport, injection and storage N2 - To set up recommendations on how to define “reasonable minimum composition thresholds” for CO2 streams to access CO2 pipeline networks, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the CCS chain. All investigations were based on a generic “CCS cluster scenario” in which CO2 streams captured from a spatial cluster of eleven emitters (seven fossil-fired power plants, two cement plants, one refinery and one steel mill) are collected in a regional pipeline network. The resulting CO2 stream (19.78 Mio t impure CO2 per year) is transported in a trunk line (onshore and offshore) and injected into five generic replicate storage structures (Buntsandstein saline aquifers) offshore. Experimental investigations and modeling of selected impacts revealed beneficial as well as adverse impacts of different impurities and their combinations. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the considered variable compositions and mass flow rates were observed. We recommend to define minimum composition thresholds for each specific CCS project through limiting i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of concentrations of critical impurities, and defining impurity combinations to be avoided. KW - Impurities KW - CO2 quality KW - Pipeline network KW - Whole-chain CCS scenario KW - Recommendations PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543004 DO - https://doi.org/10.1016/j.ijggc.2022.103589 SN - 1750-5836 VL - 114 SP - 1 EP - 14 PB - Elsevier CY - New York, NY AN - OPUS4-54300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lamoriniere, S. A1 - Mitchell, P. J. A1 - Ho, K. A1 - Kalinka, Gerhard A1 - Shaffer, M. S. P. A1 - Bismarck, A. T1 - Carbon nanotube enhanced carbon Fibre-Poly(ether ether ketone) interfaces in model hierarchical composites N2 - Poly (ether ether ketone) (PEEK) has a high continuous service temperature, excellent mechanical properties, and good solvent and abrasion resistance, which can be further improved through the addition of carbon nanotubes (CNTs). CNT-PEEK nanocomposites are promising matrices for continuous carbon fibre composites; powder processing can mitigate the high melt viscosities in these systems. In this study, model single fibre (hierarchical) composites were produced by embedding sized and desized carbon fibres in nanocomposite CNTPEEK powders followed by single fibre pull-out tests to assess interfacial characteristics. Carbon fibre-PEEK interfacial shear strength is typically 40–45 MPa. Increasing CNT loadings increased fibre-matrix interfacial shear strength linearly up to ~70 MPa at 5.0 wt%, which was attributed to the CNT-based mechanical modification of the PEEK matrix. Apparent interfacial shear strength was inversely correlated with the embedded fibre length irrespective of carbon fibre sizing or CNT loading, indicating brittle fracture of the fibre-matrix interface. Pulled out carbon fibres were still coated with the matrix, which indicated strong adhesion at the interface in all samples, likely related to a transcrystalline region. Adhesion was, however, negatively affected by the presence of epoxy sizings. Frictional shear strength was independent of embedded fibre length and CNT content for all samples. KW - Keywords: Poly(ether ether ketone) KW - Carbon fibres KW - Carbon nanotubes KW - Interfacial strength KW - Debonding PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550052 DO - https://doi.org/10.1016/j.compscitech.2022.109327 SN - 0266-3538 VL - 221 SP - 1 EP - 8 PB - Elsevier Ltd. CY - Niederlande AN - OPUS4-55005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bettge, Dirk T1 - MGA Round Robin Test on Al-AM Fatigue Testing - Fractographic Results N2 - Presentation of results of an investigation of fracture mechanisms and crack start sites of an additive manufactured aluminium alloy after fatigue testing. Collaboration within the MGA initiative (Mobility Goes Additive). T2 - MGA Mid Term Meeting 2022 CY - Berlin, Germany DA - 05.07.2022 KW - Aluminium Alloy KW - Fractography KW - Additive Manufacturing PY - 2022 AN - OPUS4-55192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Dynamic mechanical analysis of epoxy-matrix cross linking measured in-situ using an elastomer container N2 - A new patented dynamic mechanical analysis (DMA) is presented, where the tensile, bending- or torsional stiffness of a media can be characterized in-situ during the phase transition from liquid to solid. An epoxy system, e.g. Hexion L285/H287, is filled into an elastomer container, such as a silicone tube. This can be mounted into a conventional DMA and, based on a linear viscoelastic approach, the storage modulus (E’;G’), the loss modulus (E’’;G’’) and the loss angle tan(delta) can be measured at constant temperature as a function of time in order to investigate the liquid to sol-gel to solid transition. With this new method, the stiffness increase as a result of the cure process can be directly measured more precisely than with a rheometer in a shear plate set-up, because using an elastomer container gives a defined cross section for calculating the Young’s modulus. T2 - 20th European Conference on Composite Materials, ECCM20 CY - Lausanne, Switzerland DA - 26.06.2022 KW - Dynamic mechanical analysis (DMA) KW - Thermoset polymers KW - Cure process KW - Cross linking PY - 2022 AN - OPUS4-55213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Treninkov, I. A. A1 - Petrushin, N. V. A1 - Epishin, A. I. A1 - Svetlov, I. L. A1 - Nolze, Gert A1 - Elyutin, E. S. T1 - Experimental Determination of Temperature Dependence of Structural–Phase Parameters of Nickel-Based Superalloy N2 - The temperature dependences of the periods of the crystal lattices of the γ and γ' phases, their dimensional mismatch (misfit), and volume fraction of the γ' phase of an experimental single-crystal hightemperature nickel-based alloy have been determined by X-ray diffraction analysis in the temperature range of 18–1150°C. The temperature ranges in which intense changes in the structural and phase characteristics of the alloy under study take place have been determined. KW - X-ray diffraction analysis KW - High temperatures KW - Nickel-based superalloys KW - Single crystal KW - Crystal lattice period PY - 2022 DO - https://doi.org/10.1134/s2075113322010373 SN - 2075-1133 VL - 13 IS - 1 SP - 171 EP - 178 PB - Springer Science + Business Media CY - Dordrecht AN - OPUS4-54466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh T1 - Fully-reversed fatigue behavior of scarf joint repairs for wind turbine blade shell applications N2 - Due to manufacturing imperfections which can propagate to damage under in-service loads, wind turbine rotor blades, made primarily of glass fiber reinforced polymers (GFRP), often fail significantly before their design life. To enable a quick and cost-effective return to service, localized repairs can be executed by technicians in the field, directly accessing the blades by suspended roping. Scarf joint repairs, shown to be highly efficient with a smooth load transition across angled joint walls and a restored aerodynamic profile, are the focus of this study. The damage mechanisms of these structures were examined under fully-reversed mechanical cyclic loading with a load ratio R = -1, which was made possible on the coupon scale by a custom designed anti-buckling support. The number of cycles to failure were compared across load levels. While the scarf joint ratio was held constant at 1:50, known from industry and literature to be a good compromise between restored mechanical properties and repair size, the layup sequence was varied between small-to-large and large-to-small. Hereby the effect of the presence of resin pockets and fiber orientation mismatch between the parent and repair structure on the failure mechanism as well as fatigue strength of ±45° GFRP scarf joint repair structures was studied. Strain development across the joint length was measured to assess stiffness degradation in addition to the fatigue strength recovery of scarf joint structures with respect to pristine reference specimens. Grayscale analysis was used to monitor the damage state leading to fracture across the specimens. Post-mortem fractography analysis with light microscopy described the global failure mechanisms as well as local damage distribution within the structure, all of which provided insight to critical variables in scarf joint GFRP structures under fully-reversed mechanical cyclic loading, allowing for the tailoring of such repairs on wind turbine blade shells for maximum restoration of service life. T2 - 20th European Conference on Composite Materials (ECCM20) CY - Lausanne, Switzerland DA - 26.06.2022 KW - Glass fiber reinforced polymers KW - Scarf repairs KW - Fatigue PY - 2022 AN - OPUS4-55638 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönauer-Kamin, Daniela T1 - Powder-Aerosol deposited (PAD) calcium manganate as n-type thermoelectric material N2 - Currently, calcium manganate CaMnO3 and calcium cobaltite Ca3Co4O9 are being investigated as n-type resp. p-type semiconducting materials as oxidation- and temperature-resistant thermoelectric materials for oxide multilayer thermoelectric generators (TEGs). In order to manufacture multilayer TEGs, pressure-assisted sintering processes at high temperatures are necessary to achieve optimal thermoelectric material properties. To realize TEGs in planar film technology, another method to obtain dense ceramic layers directly from the synthesized starting powders without a subsequent high temperature step is emerging recently: the powder aerosol deposition (PAD) method. In the present work, it is investigated whether PAD is suitable to produce dense ceramic films from Sm-doped CaMnO3 and Ca3Co4O9 powders. The resulting thermoelectric properties are characterized as a function of temperature. CaMnO3 powder could successfully be processed by PAD with resulting layer thicknesses of 5- 6 µm without any high-temperature sintering steps of the films. The electrical conductivity and the Seebeck coefficient of the films were determined in-plane from room temperature to 600 °C in air. The results show a Seebeck coefficient of around -200 µV/K, which is comparable to results of pressed and sintered bars. At 400 °C, the electrical conductivity corresponds to the conductivity of the bar. At higher temperatures the conductivity is better than with the reference. Below 400°C, the electrical conductivity is somewhat lower than that of the reference sample, a mild thermal treatment of the PAD layer improves it. It is expected that the thermal conductivity of the PAD film will be lower compared to the bars due to the nano-crystalline film morphology. This should result in a significantly increased ZT value for the PAD layers and a higher efficiency of the TEG. The work shows that both CaMnO3 and Ca3Co4O9 can be successfully processed by PAD, and the PAD films show comparable thermoelectric properties. T2 - 18th European Conference on Thermoelectrics CY - Barcelona, Spanien DA - 14.09.2022 KW - Film depositition KW - Calcium cobaltite PY - 2022 AN - OPUS4-55771 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Junge, P. A1 - Stargardt, Patrick A1 - Kober, D. A1 - Greinacher, M. A1 - Rupprecht, C. T1 - Thermally Sprayed Al2O3 Ceramic Coatings for Electrical Insulation Applications N2 - Thermal spraying enables a fast and propelling way to additively deposit various ceramics as electric insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed materials in the coating industry since it exhibits good dielectric properties, high hardness, high melting point while still being cost-effective. Various parameters (e.g. feedstock type, plasma gas mixture, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, crystallinity, and degree of un-or molten particles. As a consequence, these parameters need to be investigated to estimate the impact on the electrical insulating properties of thermally sprayed alumina. This study focuses on the development of a novel electric insulation coating from Al2O3 feedstock powders deposited via atmospheric plasma spray (APS). The microstructure, porosity, and corresponding crystallographic phases have been analyzed with optical microscopy, XRD, and SEM images. To achieve an understanding of the parameters influencing the electrical insulation performance of the manufactured coatings, an in-depth analysis of the fundamental dielectric parameters e.g., DC resistance, breakdown strength, dielectric loss tangent, permittivity is presented. T2 - International Thermal Spray Conference and Exposition 2022 CY - Vienna, Austria DA - 04.05.2022 KW - Thermal Spray KW - Alumina KW - Dielectric properties PY - 2022 SP - 1 EP - 8 AN - OPUS4-55821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Svetlov, I. L. A1 - Epishin, A. I. A1 - Petrushin, N. V. A1 - Gerstein, G. A1 - Nolze, Gert A1 - Maier, H. J. T1 - Creep of Directionally Solidified Eutectics Ni/Ni3 Al–NbC under Thermal Cycling N2 - A nickel-based eutectic alloy with a γ/γ'-NbC structure was directionally solidified with a planar front. The specimens were tested for creep under sawtooth thermal cycling in the temperature range from 600 to 1100°C. It has been established that the lifetime under the conditions of thermal cycling is about five times shorter than it is predicted by the linear damage accumulation rule on the basis of results of isothermal creep tests. Faster creep under thermal cycling is caused by the rapid coarsening of the γ/γ' microstructure due to the periodic partial dissolution and reprecipitation of the γ' phase in heating and cooling half-cycles. KW - High temperature nickel-based eutectic alloys KW - γ/γ' matrix KW - Carbide phase NbC KW - In-situ composites KW - Creep under thermal cycling PY - 2022 DO - https://doi.org/10.1134/S2075113322040347 SN - 2075-1133 VL - 13 IS - 4 SP - 1099 EP - 1108 PB - Springer Science + Business Media CY - Dordrecht AN - OPUS4-55163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Riechers, Birte A1 - Roed, L. A1 - Mehri, S. A1 - Ingebrigtsen, T. A1 - Hecksher, T. A1 - Dyre, J. A1 - Niss, K. T1 - Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time N2 - The noncrystalline glassy state of matter plays a role in virtually all fields of materials science and offers complementary properties to those of the crystalline counterpart. The caveat of the glassy state is that it is out of equilibrium and therefore exhibits physical aging, i.e., material properties change over time. For half a century, the physical aging of glasses has been known to be described well by the material-time concept, although the existence of a material time has never been directly validated. We do this here by successfully predicting the aging of the molecular glass 4-vinyl-1,3-dioxolan-2-one from its linear relaxation behavior. This establishes the defining property of the material time. Via the fluctuation-dissipation theorem, our results imply that physical aging can be predicted from thermal-equilibrium fluctuation data, which is confirmed by computer simulations of a binary liquid mixture. KW - Physical aging KW - Equilibrium relaxation KW - Glass PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546015 DO - https://doi.org/10.1126/sciadv.abl9809 SN - 2375-2548 VL - 8 IS - 11 SP - 1 EP - 8 PB - American Association for the Advancement of Science CY - Washington, DC AN - OPUS4-54601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuser, Lina A1 - Nofz, Marianne T1 - Alkali and alkaline earth zinc and lead borate glasses: Structure and properties N2 - Low melting Li2O-PbO-B2O3, Me2O-ZnO-B2O3, Me = Li, Na, K, Rb and CaO-ZnO-B2O3 glasses were studied with Raman and infrared spectroscopies to advance the structural understanding of zinc borate glasses as potential candidates for substitution of lead containing glasses. Although the effect of type of alkali ions on the number (N4) of fourfold coordinated boron (B4) in the glasses is small, the alkali ions direct the type of borate groups, i.e., pentaborate in lithium, sodium, and calcium zinc borate glasses, as well as diborate in potassium and rubidium containing ones. Both groups were simultaneously found in Li2O-PbO-B2O3. Alkali ions are mainly responsible for the formation of B4-units and metaborate. Zinc ions favorably compensate non-bridging oxygen and partially form ZnO4. With decreasing N4 and field strength of the alkali ions the atomic packing density, glass transition temper ature and Young’s Modulus also decrease. The coefficient of thermal expansion increases with decreasing N4. KW - Raman spectroscopy KW - IR spectroscopy KW - Alkali zinc borate glasses KW - Lead borate glasses KW - Physical properties KW - Young’s Modulus PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556109 DO - https://doi.org/10.1016/j.nocx.2022.100109 SN - 2590-1591 VL - 15 SP - 1 EP - 12 PB - Elsevier CY - Amsterdam AN - OPUS4-55610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Trappe, Volker ED - Vassilopoulos, A. P. ED - Michaud, V. T1 - Fully-reversed fatigue behavior of scarf joint repairs for wind turbine blade shell applications N2 - To enable a quick and cost-effective return to service for wind turbine blades, localized repairs can be executed by technicians in the field. Scarf repairs, shown to be highly efficient with a smooth load transition across angled joint walls and a restored aerodynamic profile, are the focus of this work. The failure mechanisms of these structures were examined under quasi-static tensile and fully-reversed cyclic loading. While the scarf ratio was held constant at 1:50, the repair layup was varied between large-to-small and small-to-large. The effect of the presence of resin pockets and the fiber orientation mismatch between parent and repair material on the restored strength of BIAX ±45° glass fiber reinforced polymer scarf joint structures was studied. T2 - 20th European Conference on Composite Materials CY - Lausanne, Switzerland DA - 26.06.2022 KW - Fatigue KW - Scarf repairs KW - Glass fiber reinforced polymers PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569646 UR - https://infoscience.epfl.ch/record/298799 SN - 978-2-9701614-0-0 VL - Vol. 5 - Applications and structures SP - 195 EP - 201 PB - Composite Construction Laboratory (CCLab) CY - Lausanne AN - OPUS4-56964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cysne Barbosa, Ana Paula A1 - Azevedo do Nascimento, Allana A1 - Pavasarytė, Lina A1 - Trappe, Volker A1 - Melo, D. T1 - Effect of addition of thermoplastic self-healing agent on fracture toughness of epoxy N2 - Self-healing agents have the potential to restore mechanical properties and extend service life of composite materials. Thermoplastic healing agents have been extensively investigated for this purpose in epoxy matrix composites due to their strong adhesion to epoxy and their ability to fill in microcracks. One of the most investigated thermoplastic additives for this purpose is poly(ethylene-co-methacrylic acid) (EMAA). Despite the ability of thermoplastic healing agents to restore mechanical properties, it is important to assess how the addition of thermoplastic healing agents affect properties of the original epoxy material. In this work, EMAA was added to epoxy resin and the effect of the additive on fracture toughness of epoxy was evaluated. Results indicate that although added in low concentrations, EMAA can affect fracture toughness. T2 - 6th Brazilian Conference on Composite Materials CY - Tiradentes, Minas Gerais, Brazil DA - 14.08.2022 KW - Epoxy KW - Self-healing KW - Thermoplastic KW - Fracture PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572707 SN - 978-65-00-49386-3 DO - https://doi.org/10.29327/566492 SN - 2316-1337 SP - 219 EP - 222 AN - OPUS4-57270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Sachs, Patrick ED - Vassilopoulos, A. P. ED - Michaud, V. T1 - Dynamic mechanical analysis of epoxy-matrix cross linking measured in-situ using an elastomer container N2 - A new patented dynamic mechanical analysis (DMA) is presented, where the tensile, bending- or torsional stiffness of a media can be characterized in-situ during the phase transition from liquid to solid. An epoxy system, e.g. Hexion L285/H287, is filled into an elastomer container, such as a silicone tube. This can be mounted into a conventional OMA and, based on a linear viscoelastic approach, the storage modulus (E';G'), the loss modulus (E'';G'') and the loss angle tan(δ) can be measured at constant temperature as a function of time in order to investigate the liquid to sol-gel to solid transition. With this new method, the stiffness increase as a result of the cure process can be directly measured more precisely than with a rheometer in a shear plate set-up, because using an elastomer container gives a defined cross section for calculating the Young's modulus. T2 - 20th European Conference on Composite Materials CY - Lausanne, Switzerland DA - 26.06.2022 KW - Cross linking KW - Dynamic mechanical analysis (DMA) KW - Thermoset polymers KW - Cure process PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569651 UR - https://infoscience.epfl.ch/record/298799 SN - 978-2-9701614-0-0 VL - Vol. 5 - Applications and structures SP - 181 EP - 186 PB - Composite Construction Laboratory (CCLab) CY - Lausanne AN - OPUS4-56965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Azevedo do Nascimento, A. A1 - Trappe, Volker A1 - Diniz Melo, J. D. A1 - Cysne Barbosa, A. P. T1 - Fatigue behavior of self-healing glass fiber/epoxy composites with addition of poly (ethylene-co-methacrylic acid) (EMAA) N2 - The interest in repair technologies for polymer composites has increased significantly over the last decades, due to the growing use of these materials in structural applications. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was used as self-healing agent to glass fiber/epoxy composite. Materials with EMAA contents of 2 wt% and 5 wt% were manufactured using Resin Transfer Molding (RTM) and the effects of the healing agent on the properties were investigated using tensile tests and Dynamic Mechanical Analysis (DMA). Results show slight variation of properties, which was more pronounced as the content of EMAA increased. In addition, the healing efficiency was investigated through fatigue tests and the addition of higher content of EMAA increased the number of cycles to failure after the healing activation cycle. KW - Fatigue KW - Glass fiber-epoxy composites KW - Self-healing KW - Smart materials PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569661 DO - https://doi.org/10.1016/j.polymertesting.2022.107863 SN - 0142-9418 VL - 117 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-56966 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Malakhov, A. A1 - Epishin, A. A1 - Denisov, I. A1 - Saikov, I. A1 - Nolze, Gert T1 - Morphology and Structure of Brass–Invar Weld Interface after Explosive Welding N2 - This paper presents the results of a study of the morphology and structure at the weld interface in a brass–Invar bimetal, which belongs to the class of so-called thermostatic bimetals, or thermobimetals. The structure of the brass–Invar weld interface was analyzed using optical microscopy and scanning electron microscopy (SEM), with the use of energy-dispersive X-ray (EDX) spectrometry and back-scattered electron diffraction (BSE) to identify the phases. The distribution of the crystallographic orientation of the grains at the weld interface was obtained using an e-Flash HR electron back-scatter diffraction (EBSD) detector and a forward-scatter detector (FSD). The results of the study indicated that the weld interface had the wavy structure typical of explosive welding. The wave crests and troughs showed the presence of melted zones consisting of a disordered Cu–Zn–Fe–Ni solid solution and undissolved Invar particles. The pattern quality map showed that the structure of brass and Invar after explosive welding consisted of grains that were strongly elongated towards the area of the highest intensive plastic flow. In addition, numerous deformation twins, dislocation accumulations and shear bands were observed. Thus, based on the results of this study, the mechanism of Cu–Zn–Fe–Ni structure formation can be proposed. KW - Explosive welding KW - Thermobimetal KW - Grain structure KW - Brass KW - Invar PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565964 DO - https://doi.org/10.3390/ma15238587 SN - 1996-1944 VL - 15 IS - 23 SP - 1 EP - 10 PB - MDPI AN - OPUS4-56596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick T1 - Optimized spray granules for dry pressing by means of slurry destabilization and ultrasonic atomization N2 - The homogeneous introduction of organic additives is a prerequisite for good processability of ceramic powders during dry pressing. The addition of organic additives by wet route via ceramic slurries offers advantages over dry processing. The organic content can be reduced and a more homogeneous distribution of the additives on the particle surface is achieved. In addition to the measurements of zeta potential and viscosity, sedimentation analysis by optical centrifugation was also tested and successfully used to characterize the ceramic slurries and accurately evaluate of the suitability of different types, amounts, and compositions of organic additives. Spray drying of well-stabilized slurries usually results in mostly hollow granules with a hard shell leading to sintered bodies with defects and reduced strength and density. By purposefully degrading the slurry stability after dispersion of the ceramic powder, the drying behavior of the granules in the spray drying process and thus the granule properties can be influenced. Destabilization of the slurry and thus partial flocculation was quantified by optical centrifugation. Spray drying of the destabilized alumina slurries resulted in "non-hollow" granules without the detrimental hard shell and thus improved granule properties. Further improvement of the granules was achieved by installing ultrasonic atomization in the spray dryer. A narrower granule size distribution was achieved, which had a positive effect on, among other things, the flowability of the granules. Specimens produced from this granules had fewer defects of smaller size, leading to better results for the density and strength of the sintered bodies. The observations made for alumina could be transferred to zirconia and as well to ZTA with 20 wt% zirconia. T2 - Ceramics in Europe 2022 CY - Krakau, Poland DA - 10.07.2022 KW - Ultrasound KW - Spray drying KW - Slurry PY - 2022 AN - OPUS4-56171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A.I. A1 - Nolze, Gert A1 - Alymov, M.I. T1 - Pore Morphology in Single Crystals of a Nickel-Based Superalloy After Hot Isostatic Pressing N2 - The morphology of pores partially shrunk during a half-hour HIP at temperature of 1288 °C and pressure of 103 MPa has been investigated in nickel-based superalloy CMSX-4. The investigation resulted in the following findings: surrounding the shrinking pores by a c¢-shell (Ni3Al), faceting of the pores surface by {023} and {011} planes, and formation the submicroscopic satellite pores connected by channels with the neighboring larger pores. It is assumed that the formation of the c¢-shell around the pores and the faceting of the pore surface is due to diffusion processes occurring during pore shrinkage, and therefore these findings can be considered as arguments supporting the vacancy model of pore annihilation. The submicroscopic satellite pores are expected to be the result of dividing the casting pores of a complex initial shape during their shrinking. The connecting channels are probably required for the gas to escape from the rapidly shrinking small satellite pores into the slowly shrinking large pore. Thus, it is reasonable to assume that the casting pores may contain some amount of gas. KW - HIP KW - Superalloy KW - Porosity KW - Faceting KW - negative crystal growth PY - 2022 DO - https://doi.org/10.1007/s11661-022-06893-x SN - 1073-5623 SP - 1 EP - 9 PB - Springer Nature AN - OPUS4-56409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Junge, P. A1 - Greinacher, M. A1 - Kober, D. A1 - Stargardt, Patrick A1 - Rupprecht, C. T1 - Metastable Phase Formation, Microstructure, and Dielectric Properties in Plasma-Sprayed Alumina Ceramic Coatings N2 - The need for new solutions for electrical insulation is growing due to the increased electrification in numerous industrial sectors, opening the door for innovation. Plasma spraying is a fast and efficient way to deposit various ceramics as electrical insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed ceramics in the coating industry since it exhibits good dielectric properties, high hardness, and high melting point, while still being cost-effective. Various parameters (e.g., feedstock type, spray distance, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, and metastable phase formation. Consequently, these parameters need to be investigated to estimate the impact on the dielectric properties of plasma-sprayed alumina coatings. In this work, alumina coatings with different spray distances have been prepared via atmospheric plasma spray (APS) on copper substrates. The microstructure, porosity, and corresponding phase formation have been analyzed with optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Moreover, we present an in-depth analysis of the fundamental dielectric properties e.g., direct current (DC) resistance, breakdown strength, dielectric loss tangent, and permittivity. Our results show that decreasing spray distance reduces the resistivity from 6.31 × 109 Ωm (130 mm) to 6.33 × 108 Ωm (70 mm), while at the same time enhances the formation of the metastable δ-Al2O3 phase. Furthermore, space charge polarization is determined as the main polarization mechanism at low frequencies. KW - Alumina KW - Plasma spray KW - Dielectric properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564394 DO - https://doi.org/10.3390/coatings12121847 SN - 2079-6412 VL - 12 SP - 1 EP - 15 PB - MDPI CY - Basel AN - OPUS4-56439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nasr Esfahani, M. A1 - Zare Pakzad, S. A1 - Li, T. A1 - Li, X. A1 - Tasdemir, Z. A1 - Wollschläger, Nicole A1 - Leblebici, Y. A1 - Erdem Alaca, B. T1 - Effect of Native Oxide on Stress in Silicon Nanowires: Implications for Nanoelectromechanical Systems N2 - Understanding the origins of intrinsic stress in Si nanowires (NWs) is crucial for their successful utilization as transducer building blocks in next-generation, miniaturized sensors based on anoelectromechanical systems (NEMS). With their small size leading to ultrahigh-resonance frequencies and extreme surface-to-volume ratios, silicon NWs raise new opportunities regarding sensitivity, precision, and speed in both physical and biochemical sensing. With silicon optoelectromechanical properties strongly dependent on the level of NW intrinsic stress, various studies have been devoted to the measurement of such stresses generated, for example, as a result of harsh fabrication processes. However, due to enormous NW surface area, even the native oxide that is conventionally considered as a benign surface condition can cause significant stresses. To address this issue, a combination of nanomechanical characterization and atomistic simulation approaches is developed. Relying only on low-temperature processes, the fabrication approach yields monolithic NWs with optimum boundary conditions, where NWs and support architecture are etched within the same silicon crystal. Resulting NWs are characterized by transmission electron microscopy and micro-Raman spectroscopy. The interpretation of results is carried out through molecular dynamics simulations with ReaxFF potential facilitating the incorporation of humidity and temperature, thereby providing a close replica of the actual oxidation environment - in contrast to previous dry oxidation or self-limiting thermal oxidation studies. As a result, consensus on significant intrinsic tensile stresses on the order of 100 MPa to 1 GPa was achieved as a function of NW critical dimension and aspect ratio. The understanding developed herein regarding the role of native oxide played in the generation of NW intrinsic stresses is important for the design and development of silicon-based NEMS. KW - Nanoelectromechanical systems (NEMS) KW - Silicon nanowires KW - Native oxide KW - Intrinsic stress KW - Raman spectroscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560471 DO - https://doi.org/10.1021/acsanm.2c02983 SN - 2574-0970 VL - 5 SP - 13276 EP - 13285 PB - ACS Publ. CY - Washington, DC AN - OPUS4-56047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hemmleb, M. T1 - Integrated topographic SEM imaging for software assisted fractography N2 - The aim of a fractographic investigation is the evaluation of macroscopic and microscopic fracture surface characteristics and, as a result, the determination of the fracture mechanism of a component from a failure case. The basis for such evaluations of fracture characteristics comes from actual comparative mechanical testing and from the literature. A fractographic analysis can be very complex and, in any case, requires considerable experience. Machine learning methods enables the quantitative determination of fracture characteristics and fracture mechanisms utilizing digitized expert knowledge [1]. Although the application of SE images provides promising results, additional information is required to obtain reliable solutions. As expected, BSE and 3D information helps to improve the classification (Fig. 1). But only a fast, widely integrated, and automated topography measurement can provide the required amount of referenced surface data for the application of machine learning methods. To fulfil these requirements, topographical data are obtained from a BSE detector with four symmetric segments (4Q-BSE) using shape-from-shading technology [2]. Surface height calculation is performed live during image acquisition and provides immediate feedback in three dimensions. All available signals (SE, BSE and more if applicable) are recorded simultaneously together with the surface topography and stored in a multichannel data file. This guaranties the same geometrical reference for all data, which is required for further analysis (Fig. 2). When applying machine learning methods to topographic data together with SEM images, topographic information must be provided as depth image. Consequently, a unique height scale is required for all applied data with different magnifications. This requires a calibrated height measurement, which is ensured with the integrated 3D calibration of the topographic acquisition and a dedicated calibration sample. Thus, a large number of data sets from different fracture samples was generated and used as training data for machine learning. T2 - 16th Multinational Congress on Microscopy CY - Brno, Czech Republic DA - 04.09.2022 KW - Fractography KW - Machine Learning KW - Topography PY - 2022 AN - OPUS4-55937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmies, Lennart T1 - Using Machine Learning and Topographic SEM Imaging for Software Assisted Fractography N2 - The aim of a fractographic investigation is the evaluation of macroscopic and microscopic fracture surface characteristics and, as a result, the determination of the fracture mechanism of a component from a failure case. The basis for such evaluations of fracture characteristics comes from actual comparative mechanical testing and from the literature. A fractographic analysis can be very complex and, in any case, requires considerable experience. In the IGF project "iFrakto", software is being developed that quantitatively determines fracture characteristics and fracture mechanisms utilizing digitized expert knowledge, machine learning, and standard 2D and topographical data from SEM imaging. Topographical data are obtained from 4QBSE detector using shape-from-shading technology. In the medium term, a software tool should provide knowledge-based suggestions for the evaluation of fracture surfaces in real time during SEM work or at subsequent evaluation. As a basis for this, round robins were carried out among fractographers in order to create a knowledge base, to query the practice-relevant requirements for such tools and to carry out first practical tests. Actual results are presented and the relevance of the evaluation strategy is evaluated. T2 - Material Science and Engineering 2022 CY - Darmstadt, Germany DA - 27.9.2022 KW - Fractography KW - Machine Learning KW - Topography PY - 2022 AN - OPUS4-55938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haapalehto, Matias A1 - Pinomaa, Tatu A1 - Wang, Lei A1 - Laukkanen, Anssi T1 - An atomistic simulation study of rapid solidification kinetics and crystal defects in dilute Al–Cu alloys N2 - Rapid solidification kinetics of dilute Al–Cu alloys is simulated using a quantum mechanics based bondorder potential (BOP), in free solidification conditions, to determine kinetic and thermodynamic properties of solidification, as well as point defects and chemical ordering of the solidified structures. We measure the anisotropic kinetic coefficient, anisotropic solid–liquid interface energy, as well as solute trapping kinetics in terms of partition coefficient versus velocity and solute drag coefficient. Furthermore, solid–liquid interface free energy and its anisotropy are measured in equilibrium simulations, showing reasonably good agreement with previous studies. We also verified the self-consistency of the MD simulations, by comparing the interfacial temperature vs. velocity to that predicted by the continuous growth model. These solid–liquid interface properties are important for quantitative parametrization of larger scale solidification modeling techniques such as phase field models. We also investigated the point defect content, local chemical ordering, and local crystalline structures in the rapidly solidified samples. We found clustering of solute with vacancies, whereas copper atoms repelled each other in these dilute alloy simulations. In addition to vacancies, a large number of interstitials were found. In solidification velocities approaching the complete solute trapping regime, we found that the vacancies and interstitials formed in conjunction, i.e. as Frenkel pairs. Finally, in addition to FCC, we detected BCC and HCP phases, where the latter two were accompanied by an increase in local copper content. Understanding the formation of point defects and their relationship to chemical ordering is an important step towards controlling the formation of pre-precipitates and precipitates, which are an important strengthening mechanism for aluminum–copper alloys. KW - Rapid solidification KW - Aluminum–copper KW - MD PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628722 DO - https://doi.org/10.1016/j.commatsci.2022.111356 SN - 0927-0256 VL - 209 SP - 1 EP - 13 PB - Elsevier CY - Amsterdam AN - OPUS4-62872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guerra, E. S. S. A1 - Silva, B. L. A1 - Melo, J. D. D. A1 - Kalinka, Gerhard A1 - Barbosa, A. P. C. T1 - Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent N2 - Among the strategies to produce healable thermosetting systems is their modification by the addition of thermoplastic particles. This work investigates the influence of poly(ethylene-co-methacrylic acid) (EMAA) on fibermatrix interfacial properties of a glass fiber reinforced epoxy matrix composite. Epoxy-EMAA interactions were evaluated using differential scanning calorimetry (DSC) and infrared spectroscopy. The effects of EMAA on the epoxy network formation were evidenced by changes in glass transition temperature, cure kinetics and alteration of chemical groups during cure. Interfacial shear strength (IFSS) measurements obtained by single fiber pull-out tests indicate similar interfacial properties for pure and EMAA modified epoxy. Additionally, the potential for self-healing ability of an EMAA modified epoxy was demonstrated. However, IFSS after a healing cycle for the EMAA modified epoxy was lower as compared to the pure epoxy, because of the lower fiber-EMAA interfacial shear strength. So, thermoplastic healing agents has not only to fill cracks in the matrix material, but also have to be optimized regarding its interface properties to the reinforcing fibers. KW - Interfacial strength KW - Fiber/matrix bond KW - Self-healing KW - Polymer-matrix composites (PMC) PY - 2022 DO - https://doi.org/10.1016/j.compscitech.2022.109843 SN - 0266-3538 VL - 232 SP - 1 EP - 9 PB - Elsevier Ltd. CY - Niederlande AN - OPUS4-56379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Petrushin, N. V. A1 - Svetlov, I. L. A1 - Nolze, Gert T1 - Model for Forecasting Temperature Dependence of γ/γ' Misfit in Heat-Resistant Nickel Alloys N2 - An analytical model for forecasting the temperature dependence of γ/γ' misfit in heat-resistant nickel alloys is proposed. The model accounts for the concentration dependences of the periods of crystalline lattices of the γ and γ' phases (Vegard law), thermal expansion of the γ and γ' lattices, and dissolution of the γ' phase at high temperatures. Adequacy of calculations of misfit is confirmed by comparison with the results of measurements using methods of X-ray and neutron diffraction. The model is applied for development of a nickel alloy with positive misfit. KW - Heat-resistant nickel alloys KW - Dimensional mismatch of crystalline lattice periods (misfit) KW - Microstructure evolution PY - 2022 DO - https://doi.org/10.1134/S2075113322010105 SN - 2075-1133 VL - 13 IS - 1 SP - 7 EP - 16 PB - Springer AN - OPUS4-54379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thuy, Maximilian A1 - Pedragosa-Rincon, M. A1 - Niebergall, Ute A1 - Oehler, H. A1 - Alig, I. A1 - Böhning, Martin T1 - Environmental Stress Cracking of High-Density Polyethylene Applying Linear Elastic Fracture Mechanics N2 - The crack propagation rate of environmental stress cracking was studied on high-density polyethylene compact tension specimens under static loading. Selected environmental liquids are distilled water, 2 wt% aqueous Arkopal N100 solution, and two model liquid mixtures, one based on solvents and one on detergents, representing stress cracking test liquids for commercial crop protection products. The different surface tensions and solubilities, which affect the energetic facilitation of void nucleation and craze development, are studied. Crack growth in surface-active media is strongly accelerated as the solvents induce plasticization, followed by strong blunting significantly retarding both crack initiation and crack propagation. The crack propagation rate for static load as a function of the stress intensity factor within all environments is found to follow the Paris–Erdogan law. Scanning electron micrographs of the fracture surface highlight more pronounced structures with both extensive degrees of plasticization and reduced crack propagation rate, addressing the distinct creep behavior of fibrils. Additionally, the limitations of linear elastic fracture mechanisms for visco-elastic polymers exposed to environmental liquids are discussed. KW - Crack propagation KW - Environmental stress cracking KW - Fracture toughness KW - Crop protection products KW - High-density polyethylene KW - Craze–crack mechanism KW - Linear elastic fracture mechanics KW - Stress intensity factor PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550476 DO - https://doi.org/10.3390/polym14122415 SN - 2073-4360 VL - 14 IS - 12 SP - 1 EP - 21 PB - MDPI CY - Basel AN - OPUS4-55047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Franchin, G. A1 - Zocca, Andrea A1 - Karl, D. A1 - Yun, H. A1 - Tian, X. T1 - Editorial: Advances in additive manufacturing of ceramics N2 - Recently, additive manufacturing of ceramics has achieved the maturity to be transferred from scientific laboratories to industrial applications. At the same time, research is progressing to expand the boundaries of this field into the territory of novel materials and applications. This feature issue addresses current progress in all aspects of additive manufacturing of ceramics, from parts design to feedstock selection, from technological development to characterization of printed components. KW - Additive manufacturing KW - Ceramic PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549361 DO - https://doi.org/10.1016/j.oceram.2022.100277 SN - 2666-5395 VL - 10 SP - 1 EP - 2 PB - Elsevier CY - Amsterdam AN - OPUS4-54936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blaeß, Carsten T1 - 3D printing of crystallizing bioactive glasses N2 - Artificial bone replacement by individual customized three-dimensional resorbable bioactive glass has not yet been widely established in the clinical use. This is mainly due to the antagonism of sintering ability and suitable bioactivity. Competitive crystallization often prevents the generation of dense sintered bodies, especially for additive manufactured 3D structures. Previous studies of the fluoride-containing glass F3 have shown its potential to combine both sintering ability and suitable bioactivity. Furthermore, the occurring sintering blockade by surface crystallization of Na2CaSi2O6 was tunable by glass particle size. In this study the glasses F3, F3-Cu with 1 mol% CuO added at the expense of CaO and the well-known 13-93 were chosen to determine the influence of surface crystallization on 3D printed sinter bodies. For this purpose, grain size fractions in range of smaller 32 µm to 315 µm in fraction size of 6-20 µm were sieved from jaw crushed glass frit as well as glass cubes were cut from casted blocks for all glasses. Sintering behavior of both pressed and printed powder compacts was observed via heating microscopy. Crystallization was determined by DTA and crystallization progress was monitored on fractured sinter bodies and polished cubes via electron and laser scanning microscopy as well as with diffractometry. Depending on grain size the formation of crystalline support framework along former grain boundaries shows the capability to stabilize fully densified sinter bodies before softening. Beside of this, the generation of complex hierarchic porosity was possible as well. T2 - ICG Berlin 2022 CY - Berlin, Germany DA - 03.07.2022 KW - Bioactive Glass KW - Crystallization KW - Sintering KW - 3D printing PY - 2022 AN - OPUS4-55253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina T1 - Liquid phase sintering of alkali zinc borate glass-bearing silver pastes for applications in photovoltaics and microelectronics N2 - Liquid phase sintering of glass bearing silver pastes used in photovoltaics and microelectronics is poorly understood. In particular, the role of different network modifiers acting in the glass component and the question of the most suitable atmospheric oxygen level during sintering are still under considerable debate. To tackle these issues, low-melting and lead-free X2O-ZnO-B2O3 glasses with X = Li, Na, K and Rb (LZB, NZB, KZB and RZB) were prepared. Infrared spectroscopy showed that the glass structure was similar to each other, while an increase of tetrahedrally coordinated boron with increasing field strength of the alkali was evident. In turn, the glass transition temperature (from differential thermal analysis) increased in the order: RZB (449 °C) < KZB (460 °C) < NZB (465 °C) < LZB (472 °C). Powders of each glass were mixed with organics to receive silver-glass-pastes containing 30 vol% glass and these were subjected to heating microscopy in air. Although similar onset temperatures of sintering were recorded for Ag-NZB and Ag-LZB glass pastes, and for Ag-RZB paste and KZB-Ag-paste, respectively, differences in the crystallization behavior and final densification were observed between the former and the latter group. These were translated in terms of differences in silver dissolution and reprecipitation among the two groups. Further, running the experiments in nitrogen gas showed that sintering of all pastes was considerably hampered. The slow-down of the sinter kinetics was found to be in line with the assumed lower oxidation and dissolution of silver ions into the glass-forming liquid. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Silver metallization paste KW - Sintering KW - Glass KW - Alkali zinc borate glasses KW - Viscosity KW - Structure PY - 2022 AN - OPUS4-55728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina T1 - In situ observation of silver precipitation in sodium zinc borate glass-forming melts N2 - Melting of Na2CO3-ZnO-B2O3 batches containing up to 16.8 wt% AgNO3 (5 mol% Ag2O in the target glass composition) was observed in situ by means of hot stage microscopy. In all batches metallic silver precipitation took place as most of the silver nitrate was reduced to metallic silver before Ag+ ions could be dissolved in the evolving borate melts. In turn, only traces of Ag+ (<300 ppmw) were dissolved in the sodium zinc borate glass melts under study. It is assumed that the oxidation to Ag+ was limited due to poor availability of reducible oxygen in the glass melts and presence of Na2O being a stronger base than Ag2O. Thus, the precipitated metallic silver formed droplets of different sizes. The larger droplets (d > 20 µm) were already settled at the bottom of the container and remained constant in size upon dwelling for 1 h at 1050 °C of about one hour and the subsequent cooling (45 K/min) to room temperature, whereas the smaller droplets (d < 20 µm) were mobile in the borate melt due to Marangoni and Stokes motion. For the latter droplets, coalescence was observed in situ. A growth of larger droplets at the expense of smaller ones, i.e., Ostwald ripening was also expected but could not be studied with the used experimental equipment. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Glass melt KW - Silver KW - Sodium zinc borate glass KW - Hot stage microscopy KW - Precipitation PY - 2022 AN - OPUS4-55732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan T1 - Surface-Initiated Microstructure Formation in Glass Ceramics N2 - Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. For silicate glasses we found a good correlation between the calculated surface energy of crystal faces and oriented surface nucleation. Surface energies were estimated assuming that crystal surfaces resemble minimum energy crack paths along the given crystal plane. This concept was successfully applied by Rouxel in calculating fracture surface energies of glasses. Several oriented nucleation phenomena can be herby explained assuming that high energy crystal surfaces tend to be wetted by the melt. This would minimize the total interfacial energy of the nucleus. Furthermore, we will discuss the evolution of the microstructure and its effect on the preferred crystal orientation. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Glass KW - Oriented surface crystallization KW - Surface energy KW - Bond energy KW - Nucleation mode PY - 2022 AN - OPUS4-56070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tielemann, Christopher T1 - Oriented Surface Crystallization N2 - Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. For silicate glasses we found a good correlation between the calculated surface energy of crystal faces and oriented surface nucleation. Surface energies were estimated assuming that crystal surfaces resemble minimum energy crack paths along the given crystal plane. This concept was successfully applied by Rouxel in calculating fracture surface energies of glasses. Several oriented nucleation phenomena can be herby explained assuming that high energy crystal surfaces tend to be wetted by the melt. This would minimize the total interfacial energy of the nucleus. Furthermore, we will discuss the evolution of the microstructure and its effect on the preferred crystal orientation. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Glass KW - Surface energy KW - Crystal orientation PY - 2022 AN - OPUS4-56074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina T1 - Vacuum crack growth in silicate glasses N2 - Although the slow crack growth in glass is dominated by stress-corrosion phenomena, it also should reflect the underlaying intrinsic fracture behavior controlled by glass chemistry and structure. To investigate such underlaying phenomena, crack growth velocity in alkali silicate glasses was measured in vacuum across 10 orders of magnitude with double cantilever beam technique. Measured and literature crack growth data were compared with calculated intrinsic fracture toughness data obtained from Young’s moduli and theoretical fracture surface energy. Data analysis reveals slight correlation with the packing density and significant deviations from the intrinsic brittle fracture behavior. These deviations do not follow simple compositional trends. Two opposing processes may explain this finding: a decrease in the apparent fracture surface energy due to stress-induced chemical changes at the crack tip and its increase due to energy dissipation during fracture. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Oxide glass KW - Fracture toughness KW - Fracture surface PY - 2022 AN - OPUS4-56485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kilo, M. T1 - Glass Screening for the systematic development of new glasses N2 - Die technischen Möglichkeiten der robotischen Glasschmelzanlage der BAM werden vorgestellt. T2 - 26th International Conference on Glass CY - Berlin, Germany DA - 04.07.2022 KW - Material Digital PY - 2022 AN - OPUS4-56280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina T1 - Data-driven Workflow for Accelerated Glass Development (GlasDigital) N2 - As part of a joint project involving the Fraunhofer Institute for Silicate Research (ISC), the Friedrich Schiller University of Jena, the Clausthal University of Technology and the Federal Institute for Materials Research and Testing (BAM), digital tools are to be created for the development of new types of glass materials. Current processes for the production of glasses with improved properties are usually very cost- and energy-intensive due to the low degree of automation and are subject to long development cycles. The use of robotic synthesis processes in combination with self-learning machines is intended to overcome these problems in the long term. The development of new types of glass can then not only be accelerated considerably, but also be achieved with much less effort. In this talk, data generation via a robotic high-throughput glass melting system is presented, which should be the experimental basis for the ontology developed within the project GlasDigital. T2 - Materials Science and Engineering Congress (MSE 2022) CY - Darmstadt, Germany DA - 27.09.2022 KW - Oxidglas KW - Robotische Glasschmelzanlage PY - 2022 AN - OPUS4-56489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thuy, Maximilian A1 - Niebergall, Ute A1 - Oehler, H. A1 - Alig, I. A1 - Böhning, Martin T1 - Damaging effect of admixtures used in crop protection products on high density polyethylene packaging material N2 - The phenomenon of environmental stress cracking is still a major issue in materials engineering as well as from a scientific perspective. Especially in the case of packaging materials made of high-density polyethylene, assessing the potential of premature damage due to environmental stress cracking is complex because of the large number of components in possible liquid filling goods. As a first guideline, the well-known effect of detergents and dispersants is usually considered, but the interplay with other components, such as organic solvents is often unknown. Particularly challenging in this respect are crop protection products, consisting of several different admixtures in addition to the biologically active ingredients. This study is based on two model liquids representing these admixtures that were established for testing in this context. The model liquids as well as their constituting components were used as liquid media in the Full Notch Creep Test to characterize the environmental stress cracking behavior of a typical high-density polyethylene. Complementary to the time-to failure of a notched specimen obtained from these tests, the crack opening was monitored optically, and the fracture surface was analyzed post-failure by laser scanning microscopy as well as scanning electron microscopy. Based on the results, the effect of various surfactants as well as the influence of organic solvents on environmental stress cracking are discussed. KW - Environmental stress cracking KW - High-density polyethylene KW - Crop protection products KW - Full notch creep test KW - Fracture surface analysis KW - Crack opening displacement PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-554631 DO - https://doi.org/10.1016/j.polymertesting.2022.107672 SN - 0142-9418 VL - 114 SP - 1 EP - 16 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-55463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sommer, Konstantin A1 - Agudo Jácome, Leonardo A1 - Hesse, René A1 - Bettge, Dirk T1 - Revealing the nature of melt pool boundaries in additively manufactured stainless steel by nano-sized modulation N2 - In the current study, the 3D nature of the melt pool boundaries (MPBs) in a 316 L austenitic steel additively manufactured by laser-based powder bed fusion (L-PBF) is investigated. The change of the cell growth direction and its relationship to the MPBs is investigated by transmission electron microscopy. A hitherto unreported modulated substructure with a periodicity of 21 nm is further discovered within the cell cores of the cellular substructure, which results from a partial transformation of the austenite, which is induced by a Ga+ focused ion beam. While the cell cores show the modulated substructure, cell boundaries do not. The diffraction pattern of the modulated substructure is exploited to show a thickness ≥200 nm for the MPB. At MPBs, the cell walls are suppressed, leading to continuously connecting cell cores across the MPB. This continuous MPB is described either as overlapping regions of cells of different growing directions when a new melt pool solidifies or as a narrow planar growth preceding the new melt pool. KW - Additive manufacturing KW - Austenitic steel 316L KW - Melt pool boundary KW - Microstructural characterization KW - Transmission electron microscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547295 DO - https://doi.org/10.1002/adem.202101699 SN - 1527-2648 VL - 24 IS - 6 SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Inui, H. A1 - Kishida, K. A1 - Li, L. A1 - Manzoni, Anna Maria A1 - Haas, S. A1 - Glatzel, U. T1 - Uniaxial mechanical properties of face‑centered cubic singleand multiphase high‑entropy alloys N2 - Since the high entropy concept was proposed at the beginning of the millennium, the research focus of this alloy family has been wide ranging. The initial search for single-phase alloys has expanded with the aim of improving mechanical properties. This can be achieved by several strengthening mechanisms such as solid-solution hardening, hot and cold working and precipitation hardening. Both single- and multiphase high- and medium-entropy alloys can be optimized for mechanical strength via several processing routes, as is the case for conventional alloys with only one base element, such as steels or Ni-based superalloys. KW - High entropy alloy KW - Compositionally complex alloys KW - Tensile properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543955 DO - https://doi.org/10.1557/s43577-022-00280-y VL - 47 IS - 2 SP - 168 EP - 174 PB - Springer AN - OPUS4-54395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yesilcicek, Yasemin A1 - Haas, S. A1 - Suárez Ocano, Patricia A1 - Zaiser, E. A1 - Hesse, René A1 - Többens, D. M. A1 - Glatzel, U. A1 - Manzoni, Anna Maria T1 - Controlling Lattice Misfit and Creep Rate Through the γ' Cube Shapes in the Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy with Hf and W Additions N2 - Trace elements play an important role in the fine-tuning of complex material properties. This study focuses on the correlation of microstructure, lattice misfit and creep properties. The compositionally complex alloy Al10Co25Cr8Fe15Ni36Ti6 (in at. %) was tuned with high melting trace elements Hf and W. The microstructure consists of a γ matrix, γ' precipitates and the Heusler phase and it is accompanied by good mechanical properties for high temperature applications. The addition of 0.5 at.% Hf to the Al10Co25Cr8Fe15Ni36Ti6 alloy resulted in more sharp-edged cubic γ′ precipitates and an increase in the Heusler phase amount. The addition of 1 at.% W led to more rounded γ′ precipitates and the dissolution of the Heusler phase. The shapes of the γ' precipitates of the alloys Al9.25Co25Cr8Fe15Ni36Ti6Hf0.25W0.5 and Al9.25Co25Cr8Fe15Ni36Ti6Hf0.5W0.25, that are the alloys of interest in this paper, create a transition from the well-rounded precipitates in the alloy with 1% W containing alloy to the sharp angular particles in the alloy with 0.5% Hf. While the lattice misfit has a direct correlation to the γ' precipitates shape, the creep rate is also related to the amount of the Heusler phase. The lattice misfit increases with decreasing corner radius of the γ' precipitates. So does the creep rate, but it also increases with the amount of Heusler phase. The microstructures were investigated by SEM and TEM, the lattice misfit was calculated from the lattice parameters obtained by synchrotron radiation measurements. KW - High entropy alloy KW - Lattice misfit KW - Creep KW - Transmission electron microscopy KW - X-ray diffraction PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565655 DO - https://doi.org/10.1007/s44210-022-00009-1 SP - 1 EP - 9 PB - Springer AN - OPUS4-56565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuser, Lina A1 - Nofz, Marianne A1 - Müller, Ralf T1 - Alkali and alkaline earth zinc and lead borate glasses: Sintering and crystallization N2 - Glasses in the systems Me2O-ZnO-B2O3 with Me = Li, Na, K, Rb (MeZB), Na2O-ZnO-CuO-B2O3 (NZCuB), CaO-ZnO-B2O3 (CaZB), and Li2O-PbO-B2O3 (LPbB) as a reference, were studied by differential thermal analysis, dilatometry, rotational viscometry, and heating microscopy. A decrease of viscosity and sintering range was found with decreasing number of fourfold coordinated boron. The viscosity of the alkali zinc borate glasses varies only slightly. LPbB and CaZB stand out by their reduced and increased viscosities, respectively. Sodium, potassium, and calcium zinc borate glasses possess a fragility above 76. All glasses were sintered to full density before crystallization. Mostly binary zinc borate phases govern crystallization. A ternary crystalline phase was detected only in the potassium containing sample. The Weinberg glass stability parameter ranges between 0.07 and 0.12. This is caused by the presence of several crystalline phases and varying melting points of even the same crystalline phase in different glass matrices. KW - Alkali zinc borate glasses KW - Lead borate glasses KW - Viscosity KW - Sintering KW - Crystallization KW - Fragility PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556128 DO - https://doi.org/10.1016/j.nocx.2022.100116 SN - 2590-1591 VL - 15 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-55612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf T1 - Sintering and foaming of bioactive glasses N2 - Sintering, crystallization, and foaming of 44.8SiO2–2.5P2O3–36.5CaO–6.6Na2O–6.6K2O–3.0CaF2 (F3) and 54.6SiO2–1.7P2O3–22.1CaO–6.0Na2O–7.9K2O–7.7MgO (13–93) bioactive glass powders milled in isopropanol and CO2 were studied via heating microscopy, differential thermal analysis, vacuum hot extraction (VHE), Infrared spectroscopy, and time-of-flight secondary ion mass spectrometry. Full densification was reached in any case and followed by significant foaming. VHE studies show that foaming is driven by carbon gases and carbonates were detected by Infrared spectroscopy to provide the major foaming source. Carbonates could be detected even after heating to 750◦C, which hints on a thermally very stable species or mechanical trapping. Otherwise, dark gray compact colors for milling in isopropanol indicate the presence of residual carbon as well. Its significant contribution to foaming, however, could not be proved and might be limited by the diffusivity of oxygen needed for carbon oxidation to carbon gas. KW - Bioactive Glass KW - Crystallization KW - Foaming KW - Sintering PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552454 DO - https://doi.org/10.1111/jace.18626 SN - 0002-7820 SP - 1 EP - 11 PB - Wiley online library AN - OPUS4-55245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuser, Lina A1 - Nofz, Marianne A1 - Müller, Ralf A1 - Deubener, J. T1 - Silver dissolution and precipitation in an Na2O–ZnO–B2O3 metallization paste glass N2 - Thermally stimulated interactions between silver and glass, that is, silver dissolution as Ag+ and precipitation as Ag0 were studied in two glass series of molar target composition xAg2O–(19 − x)Na2O–28ZnO–53B2O3 with x = 0, 0.1, 0.5, 5 and (19Na2O–28ZnO–53B2O3)+yAg2O with y = 0.01, 0.05. These act as model for low-melting borate glasses being part of metallization pastes. The occurrence of metallic silver precipitates in melt-quenched glass ingots demonstrated that silver dissolved only in traces (< 0.01 mol%) in the glasses. The dissolved silver was detected by means of Raman spectroscopy and energy-dispersive X-ray spectroscopy. Increasing x in the batch could not lead to a significant increase of the silver ion fraction in the glass as possible in binary silver borate glasses. In situ observation of heated AgNO3 mixed with the base glass frit in a hot stage microscope showed that Ag0 precipitation occurs already at the solid state. At higher temperatures, small droplets of liquid silver were found to move freely within the melt, whereas coalescence caused a stepwise increase of their size. These results contribute to the understanding of formation of silver precipitates in metallization pastes described in the literature. KW - Silver metallization paste KW - Batch reactions KW - Borate KW - Glass forming melts KW - Glass manufacturing KW - Raman spectroscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559433 DO - https://doi.org/10.1111/ijag.16613 SN - 2041-1286 SP - 1 EP - 11 PB - Wiley Online Library AN - OPUS4-55943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manzoni, Anna Maria A1 - Mohring, Wencke A1 - Hesse, René A1 - Agudo Jácome, Leonardo A1 - Stephan-Scherb, C. T1 - Early material damage in equimolar CrMnFeCoNi in mixed oxidizing/sulfiding hot gas atmosphere N2 - The challenges to use more varied fuels at medium and high temperatures above 500 °C need to be addressed by tuning the materials toward a better resistance against increased corrosion. As a first step the corrosion processes need to be better understood, especially in the case of the unavoidable and highly corrosive sulfur-based gases. Herein, oxidation/sulfidation of an equimolar CrMnFeCoNi high-entropy alloy is studied at an early stage after hot gas exposure at 600 °C for 6 h in 0.5% SO2 and 99.5% Ar. The oxidation process is studied by means of X-ray diffraction, scanning and transmission electron microscopy, and supported by thermodynamic calculations. It is found that the sulfur does not enter the bulk material but interacts mainly with the fast-diffusing manganese at grain boundary triple junctions at the alloy surface. Submicrometer scaled Cr–S–O-rich phases close to the grain boundaries complete the sulfur-based phase formation. The grains are covered in different Fe-, Mn-, and Cr-based spinels and other oxides. KW - High entropy alloy KW - Sulfiding KW - Corrosion KW - Transmission electron microscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543495 DO - https://doi.org/10.1002/adem.202101573 SN - 1527-2648 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54349 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Manzoni, Anna Maria T1 - Early Material Damage in Equimolar CrMnFeCoNi in Mixed Oxidizing/Sulfiding Hot Gas Atmosphere N2 - The challenges to use more varied fuels at medium and high temperatures above 500 °C need to be addressed by tuning the materials towards a better resistance against increased corrosion. As a first step the corrosion processes need to be better understood, especially in the case of the unavoidable and highly corrosive sulfur-based gases. In this work oxidation/sulfidation of an equimolar CrMnFeCoNi high entropy alloy is studied at an early stage after hot gas exposure at 600 °C for 6 h in 0.5% SO2 and 99.5% Ar. The oxidation process is studied by means of x-ray diffraction, scanning and transmission electron microscopy and supported by thermodynamic calculations. It is found that the sulfur does not enter the bulk material but interacts mainly with the fast-diffusing manganese at grain boundary triple junctions at the alloy surface. Sub-micrometer scaled Cr-S-O rich phases close to the grain boundaries complete the sulfur-based phase formation. The grains are covered in different Fe, Mn and Cr based spinels and other oxides. T2 - Priority Programme (Schwerpunktprogramm) Compositionally Complex Alloys - High Entropy Alloys (SPP CCA - HEA) CY - Bayreuth, Germany DA - 12.07.2022 KW - High entropy alloy KW - Corrosion KW - Sulfiding KW - Cantor alloy KW - Transmission electron microscopy PY - 2022 AN - OPUS4-55395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Suárez Ocaño, Patricia A1 - Agudo Jácome, Leonardo T1 - Creep degradation of the high entropy superalloy AlMo0.5NbTa0.5TiZr N2 - The refractory high entropy superalloy (RSA) AlMo0.5NbTa0.5TiZr was the first of a class, with a dual-phase microstructure that resembles that of γ/γ’ in Ni-base superalloys), and the open question whether it performs better as structural alloy under high temperature (HT) applications. Here, we address the HT creep behavior and its associated microstructural degradation of this RSA. The material was produced by arc-melting, heat treatment in argon (24 h @ 1400 °C + 4 h hot isostatic pressure @ 1370 °C & 170 MPa). Interrupted vacuum creep tests were performed at 900-1100 °C and 30-120 MPa. Scanning (S) and transmission (T) electron microscopy (EM) were used to reveal degradation mechanisms. At 1100 °C (Fig.1, middle), the dual A2/B2 microstructure coarsens and partially transforms into a Zr-Al-rich phase (red arrow). An additional external load pronounces directional coarsening. Results are further discussed on the base dislocation and additional damage mechanisms. T2 - International Conferende on Strength of Materials (ICSMA) 2022 CY - Metz, France DA - 26.06.2022 KW - High entropy superalloy KW - Rrafting KW - Dislocation creep KW - Phase transformation PY - 2022 AN - OPUS4-63856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, F. A1 - Cheng, J. A1 - Liang, S. B. A1 - Ke, C. B. A1 - Cao, S. S. A1 - Zhang, X. P. A1 - Zizak, I. A1 - Manzoni, Anna Maria A1 - Yu, J. M. A1 - Wanderka, N. A1 - Li, W. T1 - Formation and evolution of hierarchical microstructures in a Ni-based superalloy investigated by in situ high-temperature synchrotron X-ray diffraction N2 - Hierarchical microstructures are created when additional γ particles form in γ’ precipitates and they are linked to improved strength and creep properties in high-temperature alloys. Here, we follow the formation and evolution of a hierarchical microstructure in Ni86.1Al8.5Ti5.4 by in situ synchrotron X-ray diffraction at 1023 K up to 48 h to derive the lattice parameters of the γ matrix, γ’ precipitates and γ particles and misfits between phases. Finite element method-based computer simulations of hierarchical microstructures allow obtaining each phase's lattice parameter, thereby aiding peak identification in the in situ X-ray diffraction data. The simulations further give insight into the heterogeneous strain distribution between γ’ precipitates and γ particles, which gives rise to an anisotropic diffusion potential that drives the directional growth of γ particles. We rationalize a schematic model for the growth of γ particles, based on the Gibbs-Thomson effect of capillary and strain-induced anisotropic diffusion potentials. Our results highlight the importance of elastic properties, elastic anisotropy, lattice parameters, and diffusion potentials in controlling the behavior and stability of hierarchical microstructures. KW - XRD KW - Superalloy KW - Finite element method KW - Transmission electron microscopy PY - 2022 DO - https://doi.org/10.1016/j.jallcom.2022.165845 SN - 0925-8388 VL - 919 SP - 1 EP - 17 PB - Elsevier CY - Lausanne AN - OPUS4-55394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kingsbery, Phillip A1 - Stephan-Scherb, Christiane T1 - Effect of KCl deposits in high‐temperature corrosion on chromium‐rich steels in SO2‐containing atmosphere N2 - High‐temperature corrosion was studied under multiple chemical loads on ferritic‐austenitic model alloys (Fe–13Cr, Fe–18Cr–12Ni, and Fe‐25Cr–20Ni) with KCl deposit under 0.5% SO2/99.5% Ar gas atmosphere at 560°C. Postexposure characterization was done by X‐ray diffraction and scanning electron microscopy. In a pure SO2/Ar environment a protective Cr2O3 scale was formed by all samples. The introduction of KCl deposits causes the scale to be nonprotective and multilayered, consisting of CrS, FeS, Cr2O3, Fe3O4, and Fe2O3. The impact of the microstructure and alloying elements is discussed. KW - High‐temperature corrosion KW - KCl KW - Microstructure KW - SO2 KW - Steel alloy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543056 DO - https://doi.org/10.1002/maco.202112901 VL - 73 IS - 5 SP - 758 EP - 770 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo T1 - Navigating the Nanoworld: Understanding Materials Properties with the Transmission Electron Microscope N2 - The field of materials science is defined as “the study of the properties of solid materials and how those properties are determined by a material’s composition and structure.”. Many –if not most– of the materials that are produced nowadays owe their properties to structures engineered down to the nanoscopic level. This need has been partly realized thanks to the understanding of materials’ building blocks via characterization techniques that reach this level of resolution. Transmission electron microscopy, since its first implementation in the early 1930s (in Berlin), has been implemented to achieve imaging –and spectral– analysis at lateral resolutions down to the atomic level. In this contribution, a series of practical examples will be presented, where applied materials are characterized by a range of transmission electron microscopy techniques to understand structural and functional properties of a wide range of materials. Among these materials examples will be presented on structural conventionally and additively manufactured metallic alloys, high entropy alloys, dissimilar aluminum-to-steel welds, magnetic nanoparticles, ceramic coatings, high temperature oxidation products. Addressed will be either the effect of processing route or that of the exposure to experimental conditions similar to those found in the respective intended applications. T2 - UA/UAB/UAH MSE Graduate Seminar CY - Online meeting DA - 19.01.2022 KW - Transmission electron microscopy (TEM) KW - Characterization KW - Microstructure KW - 3D PY - 2022 AN - OPUS4-54238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Manzoni, Anna Maria T1 - Early Material Damage in Equimolar CrMnFeCoNi in Mixed Oxidizing/Sulfiding Hot Gas Atmosphere N2 - The use of more and more varied fuels implies an increased list of criteria that need to be addressed when choosing a material for a combustion chamber and its supply pipes. The materials must be very resistant against corrosion, especially when the process takes place at temperatures above 500°C. In this work the influence of SO2 on the surface of the “Cantor alloy” is investigated. T2 - HEA-Symposium "Potential for industrial applications" CY - Dresden, Germany DA - 12.05.2022 KW - High entropy alloy KW - Corrosion KW - Sulfiding KW - Transmission electron microscopy PY - 2022 AN - OPUS4-55397 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rodrigues, A. C. P. A1 - Feller, A. A1 - Agudo Jácome, Leonardo A1 - Azevedo, C. R. F. T1 - Use of synthetic Fe3O4-rich tribofilms to investigate the effect of microconstituents, temperature and atmosphere on the friction coefficient during pin-on-disc tribotest N2 - This work investigates the effect of the tribotesting parameters (temperature, atmosphere, and third body chemical composition) on the coefficient of friction (CoF) during pin-on-disc dry (PoD) sliding tribotests using artificial third bodies. The third body comprised nanometric Fe3O4-based binary to quaternary chemical compositions containing copper, graphite, and zirconia. These mixtures were manually or ball-milled prepared, and pin-on-disc tribotests were conducted at 23 °C and 400 °C under air or nitrogen atmospheres. Combining PoD and artificial third body to create synthetic tribofilms might be useful for testing new formulations of Cu-free friction materials. Microstructural characterisation of the tribofilms was used to study the stability of the Fe3O4, copper, and graphite nanoparticles under different testing conditions to understand their effects on the CoF. For the Fe3O4-C-ZrO2-X systems, the ball milling mixing promoted the formation of turbostratic graphite in the tribofilm, impairing the lubricating effect of the graphite under air atmosphere at 23 °C. The formation of monoclinic CuO in the tribofilms during tribotests at 400 °C under air and N2 atmospheres promoted a lubricating effect. KW - Tribology KW - Microstructure KW - Oxide KW - Transmission electron microscopy PY - 2022 DO - https://doi.org/10.1088/2051-672X/ac9d51 SN - 2051-672X VL - 10 IS - 4 SP - 044009-1 EP - 044009-18 PB - IOP Pobilishing AN - OPUS4-56467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina T1 - Damage induced by electric field of microparticles in the electron microscope N2 - Damage induced by electric field (DIEF) that happens in the transmission electron microscope (TEM) when converging the electron beam (e-beam) on microparticles (MPs) can be used to synthesis new nanomaterial and nanomaterial compositions. The research questions are to clarify the limits and possibilities of the method regarding materials that can be produced, systems to which it is applicable and working beam parameters. Synthesis of nano-objects from microparticles using DIEF in TEM could be shown for different materials. Additionally, DIEF using the e-beam in a scanning electron microscope (SEM) can also be used to synthesis nano-objects. A deeper material analysis of this nano-objects was done using TEM and shows that the material of the nanoparticles (NPs) can be gold or/and silicon. Furthermore, the size of the NPs depends on the distance to the center of DIEF whereby the larger NPs are closer to the center. The areas of gold NPs are promising candidates for plasmonic or photonic devices for energy storage or transport. T2 - PhD-Day 2022 CY - Berlin, Germany DA - 06.09.2022 KW - Electron microscopy KW - Electron beam induced modification KW - Gold nanoparticles PY - 2022 AN - OPUS4-58264 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo T1 - Revealing the Nature of Melt Pool Boundaries in Additively Manufactured Stainless Steel by Nano-sized Modulation N2 - Additive manufacturing (AM) of metallic alloys has gained momentum in the past decade for industrial applications. The microstructures of AM metallic alloys are complex and hierarchical from the macroscopic to the nanometer scale. When using laser-based powder bed fusion (L-PBF) process, two main microstructural features emerge at the nanoscale: the melt pool boundaries (MPB) and the solidification cellular substructure. Here, details of the MPB are revealed to clearly show the three-dimensional nature of MPBs with changes of cell growth of direction and their relation to their surrounding cellular substructure, as investigated by transmission electron microscopy (TEM) for L-PBF 316L austenitic stainless steel (cf. Figure 1). A hitherto unknown modulated substructure with a period of 21 nm is further discovered within cells as the result of a partial Ga+-focused ion beam-induced ferritic transformation of the austenite. Cell cores and cell boundaries differ notably regarding the modulated substructure. T2 - 3. Fachtagung Werkstoffe und Additive Fertigung 2022 CY - Dresden, Germany DA - 11.05.2022 KW - Additive manufacturing KW - Austenitic steel 316L KW - Melt pool boundary KW - Microstructural characterization KW - Transmission electron microscopy PY - 2022 AN - OPUS4-54836 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina T1 - Silver in low-melting alkali zinc borate glasses N2 - Ein aktuelles Forschungsziel ist die Substitution von Bleioxid in niedrig schmelzenden Gläsern z.B. zur Anwendung in Silber-Metallisationspasten. Im Fokus steht hier die Untersuchung der Silberdiffusion in Alkali-Zink-Boratgläsern (X2O-ZnO-B2O3, X = Li, Na, K, Rb). Zudem wird der Redoxzustand des Silbers (Ag) und somit die Art der diffundierenden Silberspezies bestimmt. Hierzu wurde eine metallische Silberschicht mittels Sputterns auf Glaswürfel aufgebracht. Die Wärmebehandlung erfolgte nahe der Glasübergangstemperatur bei 470 °C über 2 h unter Luft und Stickstoffatmosphäre. Die Schichtdicke der Silberbeschichtung betrug 1.8 µm nach der Wärmebehandlung, gemessen mittels Weißlicht-Interferometer. Die Silberdiffusionsprofile wurden mittels Sekundär-Neutral-Teilchen-Massenspektrometrie gemessen. Die Diffusionskoeffizienten des Silbers liegen in der Größenordnung von ~10-14 cm2/s und unterscheiden sich nur gering in Abhängigkeit des Alkali-Ions im Glas. Mittels Fluoreszenz-Spektroskopie ließen sich gelöste Ag+-Ionen und [Agm]n+-Cluster nach der Wärmebehandlung unterscheiden. Zusätzlich konnten ausgeschiedene metallische Silber-Partikel im Natrium-enthaltenden Glas mittels Transmissionselektronenmikroskopie beobachtet werden. Diese haben einen mittleren Durchmesser von ~6 nm. N2 - Substitution of lead oxide in low-melting glasses, e.g., for application in silver metallization pastes, is a current research goal. This work is focused on the investigation of silver diffusion in alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb). In addition, the redox state of silver (Ag) and thus the type of diffusing silver species were studied. For this purpose, a metallic silver coating was applied on glass cubes by means of sputtering. Heat treatment of the samples was performed close to the glass transition temperatures at 470 °C for 2 h under air and nitrogen atmosphere. Coating thickness was 1.8 µm after heat treatment, measured by a white light interferometer. Silver diffusion profiles were measured by means of secondary neutral mass spectrometry. The silver diffusion coefficients are in the range of ~10-14 cm2/s and indicate no significant differences depending on the type of alkali ions in the glass. Dissolved Ag+-ions and [Agm]n+-clusters in the glasses were differentiated using fluorescence spectroscopy. Precipitated metallic silver particles in the sodium containing glass were observed by means of transmission electron microcopy. Their mean particle diameter was ~6 nm. T2 - Living Glass Surfaces XI - Year of Glass CY - Ilmenau, Germany DA - 14.09.2022 KW - Alkali zinc borate glasses KW - Silver diffusion KW - Transmission electron microscopy KW - Fluorescence spectroscopy KW - Silver cluster PY - 2022 AN - OPUS4-55736 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fantin, Andrea A1 - Cakir, Cafer Tufan A1 - Kasatikov, S. A1 - Schumacher, G. A1 - Manzoni, Anna Maria T1 - Effects of heat treatment on microstructure, hardness and local structure in a compositionally complex alloy N2 - Unlike conventional alloys, high entropy alloys are characterized by one or more solid solution phase(s) without a clearly defined solvent, all element contribute to the matrix in a way that is still not entirely understood. In addition, it is not known to what extent classic thermodynamic rules can be applied to these multi-element alloys, especially concerning the question about what factor incites the matrix to undergo a phase transformation. This work tackles directly some of these aspects on a chosen alloy, Al8Cr17Co17Cu8Fe17Ni33 (at.%), which presents a high temperature single-phase γ state and a two-phase state with γ′ precipitates, above and below 900 ◦C, respectively. A combined investigation via microstructural observations, hardness testing, X-ray absorption and photoelectron spectroscopy was carried out above the γ′ formation temperature. Hardness values are independent of the annealing temperatures, microstructural analysis shows no phase formation and X-ray absorption spectroscopy does not reveal observable changes in neither local atomic nor electronic structure, indicating that approaching γ′ formation temperature is not influenced by atomic or electronic rearrangements. Interestingly, short-range chemical order remains quantitatively compatible at any annealing temperature in the single-phase γ state, and the observed preferred pairs Al–Cu and Al–Ni in the γ state match with the γ’ precipitates composition below 900 ◦C. KW - High entropy alloys KW - EXAFS KW - Short range order KW - Vickers hardness PY - 2022 DO - https://doi.org/10.1016/j.matchemphys.2021.125432 SN - 0254-0584 VL - 276 SP - 125432 PB - Elsevier B.V. AN - OPUS4-53760 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Numerical study of electric field distribution in breakdown strength testing of ceramics N2 - Dielectric breakdown of insulators is a combined electrical, thermal, and mechanical failure. The exact breakdown mechanism in ceramics and the formulation of useful models are still subject of investigation. Recent studies highlighted that several experimental aspects of dielectric breakdown strength testing affect the test results, and thus impede the recognition of fundamental principles. Excess field strength near the electrode can lead to premature breakdown in the insulating liquid. This would cause superficial damage to the test specimen and thus falsify the measurement results. The field strength distribution is influenced by the ratio of permittivity of the sample and the surrounding insulating liquid. Premature breakdown depends on the breakdown strength of the liquid and the actual test voltage. The test voltage again depends on the specimen thickness. To systematically investigate these relations, a numerical simulation study (FEM) of the electric field distribution in a typical testing rig with cylindrical electrodes was performed. The permittivity of the sample and the insulating liquid was parameterized, as well as the sample thickness. The electric field distribution was calculated for increasing test voltage. Field strength maxima are compared to experimental breakdown strength of typical insulating liquids and experimental breakdown locations on alumina. Strategies are discussed to adjust the insulation liquid and the sample thickness to reduce the influence of the testing setup on the dielectric breakdown strength results. T2 - Ceramics in Europe 2022 CY - Krakow, Poland DA - 10.07.2022 KW - Ceramics KW - Dielectric breakdown strength KW - Electric field distribution KW - Alumina PY - 2022 AN - OPUS4-55325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beygi Nasrabadi, Hossein T1 - Domain-level ontology formulation based on the Platform Material Digital (PMD) ontology: case study Brinell hardness N2 - A large amount of publicly available data is reproduced every day in the field of materials science, while these kind of material data can have different formats and types like paper-type publications, standards, datasheets or isolated datasets in repositories. However, gathering a specific library from such extensive and diverse material data is always challenging for the materials scientists and engineers, since the time-related limitations are not allowed to fully access the large publicly available databases; search across these disparate databases, manage the large volumes of heterogeneous datasets, and integrate data from multiple sources. To address these challenges and make data findable, accessible, interoperable, and reusable (FAIR), an efficient data management system is necessary to build comprehensive, documented, and connected data spaces in the future. A formal standardized knowledge representation through an ontology can address such problems and make data more available and interoperable between related domains. Ontology can also rich machine processable semantic descriptions that increases the performance of scientific searches. In this regard, the Platform MaterialDigital (PMD) is currently working on developing a high-level ontology for the materials and material related processes. For example, in one of the PMD projects of “KupferDigital”, we will try to develop a data ecosystem for digital materials research based on ontology-based digital representations of copper and copper alloys. As a case study, this paper describes the methodology for ontology development of Brinell hardness, based on PMD core ontology. The methodology we describe includes the following steps; gathering the required domain terminology from different resources like standards (DIN EN ISO 6506-1) and test reports, representing the performance of a standard-conformant hardness test and the treatment of the recorded values up to a “reportable” hardness value for a material, designing the process chain according to the semantic technologies, and developing a domain-level ontology of Brinell hardness based on PMD ontology semantic formalization. Apart the mentioned methodology, some interesting tools and methods were introduced and ontology design challenges and possible solutions for modelling materials and processes were discussed. Furthermore, a dataset from the Brinell hardness measurement of cast copper samples is prepared for testing the query process. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Copper KW - Materials Science KW - Ontology KW - Platform MaterialDigital (PMD) KW - Brinell hardness PY - 2022 AN - OPUS4-56092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chen, Yue T1 - Ontopanel: a diagrams.net plugin for graphical semantic modelling N2 - Ontologies that represent a map of the concepts and relationships between them, are becoming an effective solution for data standardization and integration of different resources in the field of materials science, as efficient data storage and management is the building block of material digitization. However, building a domain ontology is not a simple task. It requires not only a collaborative effort between ontologists and domain experts, but also the modeling approaches and tools play a key role in the process. Among all approaches, graphical representation of domain ontologies based on standard conceptual modeling languages is widely used because of its intuitiveness and simplicity. Various tools have been developed to realize this approach in an intuitive way, such as Protégé plugins and web visualization tools. The Materials-open-Lab (MatOLab) project, which aims to develop ontologies and workflows in accordance with testing standards for the materials science and engineering domains, adopted a UML (Unified Modeling Language) approach based on the diagrams.net. It is a powerful, popular, open-source graphical editor. In practical case studies, however, many users’ needs could not be met, such as reusing ontology, conversion, and data mapping. Users must switch between different tools to achieve a certain step, and thereby invariably increase learning cost. The lack of validation also leads to incorrect diagrams and results for users who are not familiar with the ontology rules. To address these issues, we designed Ontopanel, a diagrams.net-based plugin that includes a set of pipeline tools for semantic modeling: importing and displaying protégé-like ontologies, converting diagrams to OWL, validating diagrams by OWL rules, and mapping data. It uses diagrams.net as the front-end for method modeling and Django as the back-end for data processing. As a web-based tool, it is very easy to expand its functionality to meet changing practical needs. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Ontology KW - Tools KW - Material digital KW - Mat-o-lab KW - Graphic design KW - Ontology development KW - Data mapping KW - FAIR KW - Materials testing PY - 2022 AN - OPUS4-55884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Han, Ying T1 - The influence of aging and mean stress on fatigue of Al-alloy EN AW-2618A N2 - In this study, the influence of aging and mean stress on fatigue of the aluminium-alloy EN AW-2618A is investigated. Therefore axial fatigue tests are carried out on smooth specimens. The experiments show that the fatigue life decreases with increasing mean stress. Furthermore, the tests with the overaged specimens demonstrate that the number of cycles to failure is decreasing with increasing aging time. T2 - LCF9 CY - Berlin, Germany DA - 21.06.2022 KW - Fatigue KW - Aluminium alloy KW - EN AW-2618A KW - Damage Behavior PY - 2022 AN - OPUS4-55125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eisenbart, M. T1 - Development of an ontology for the lifecycle of copper and copper alloys N2 - Efforts towards digitalization in the material science and technology community have enhanced in the last years. In 2019 the German digitalization initiative platform „MaterialDigital“1 (MD) has been started. Numerous projects concerning digitalization, including the copper related project „KupferDigital“ (copper digital) have been initiated under the umbrella of MD. The initiative strives to address numerous issues concerning data access, exchange, security, provenance and sovereignty. Heterogeneous data origin, storage and evaluation often result in problems concerning comparability and reproducibility of scientific and technological results. In many cases material data are recorded, but the methods of testing are insufficiently described, or such information is not communicated along with the raw data. The material data can also have numerous different formats such as paper printouts, pdfs, excel sheets or csv-files. Hence, gathering and integrating material data from different sources is challenging for potential users like materials scientists and engineers, especially if there are contradictory data where the reasons for contradictions is not clear due their vague description. In order to address these problems, data should comply to the so called „FAIR“ principle which calls for data to be findable, accessible, interoperable, and reusable (FAIR)2 and hence be accessible via so-called decentralized but interconnected data spaces. By using knowledge representation withontologies, data can be enriched with meaning and the methods of the testing procedures can be accurately provided. In this presentation we want to introduce our approach to such knowledge representation based on a high-throughput alloy development process for Cu-based alloys³ along with characterization techniques such as hardness testing and microstructural characterization (e.g. EBSD – Electron Backscattered Diffraction). T2 - Copper Alloys Conference CY - Dusseldorf, Germany DA - 22.11.2022 KW - Copper KW - Life cycle KW - Ontology PY - 2022 AN - OPUS4-56406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shakeel, Y. T1 - NFDI-MatWerk - Reference Datasets N2 - Within NFDI-MatWerk (“National Research Data Infrastructure for Material Sciences”/ “Nationale Forschungsdateninfrastruktur für Materialwissenschaften und Werkstofftechnik“), the Task Area Materials Data Infrastructure (TA-MDI) will provide tools and services to easily store, share, search, and analyze data and metadata. Such a digital materials environment will ensure data integrity, provenance, and authorship. The MatWerk consortium aims to develop specific solutions jointly with Participant Projects (PPs), which are scientific groups or institutes covering different domains, from theory and simulations to experiments. The Data Exploitation Methods group of the Karlsruhe Institute of Technology-Steinbuch Centre of Computing, as part of TA-MDI, is developing specific solutions in close collaboration with three PPs. PP07, together with the University of Stuttgart, aims at the image-based prediction of the material properties of stochastic microstructures using large-scale supercomputers. PP13, in cooperation with the University of Saarland, focuses on tomographic methods at various scales in materials research. PP18, together with the Federal Institute for Materials Research and Testing (“Bundesanstalt für Materialforschung und -prüfung”), aspires to define the criteria for materials reference datasets and usage analytics. The requirements and goals are comparable for each PP: their research outputs, which are scientific datasets, should conform to the FAIR (Findable, Accessible, Interoperable, Reusable) principles. We aim to shape them from a data management perspective making use of the FAIR Digital Object concept, including structured metadata and storage solutions. The results will be a blueprint which will act as a reference for future datasets. Even though the collaboration is in an early stage, the initial steps already show the added value of this approach. This research has been supported by the Federal Ministry of Education and Research (BMBF) – funding code M532701 / the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project number NFDI 38/1, project no. 460247524. T2 - HMC Conference 2022 CY - Online meeting DA - 05.10.2022 KW - NFDI KW - NFDI-MatWerk KW - Reference Data KW - FAIR KW - Creep PY - 2022 AN - OPUS4-56611 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Sonntag, Nadja A1 - Jürgens, M. A1 - Uhlemann, Patrick A1 - Skrotzki, Birgit A1 - Olbricht, Jürgen T1 - Datasets for Service-Like Creep-Fatigue Experiments on Grade P92 Steel N2 - The dataset contains experimental mechanical data from complex service-like creep-fatigue experiments performed isothermally at 620 °C and a low strain amplitude of 0.2 % on tempered martensite-ferritic grade P92 steel. The data sets in text file format provide cyclic deformation (min. and max. stresses) and the total (hysteresis) data of all recorded fatigue cycles for three different creep-fatigue experiments: 1) a standard relaxation fatigue (RF) test with symmetrical dwell times of three minutes introduced at minimum and maximum strain, 2) a fully strain-controlled service-like relaxation (SLR) test combining these three-minute peak strain dwells with a 30-minute dwell in between at zero strain, and 3) a partly stress-controlled service-like creep (SLC) test combining the three-minute peak strain dwells with 30-minute dwells at constant stress. Further information on data and data acquisition, analysis, and experimental details are given in “Experimental Data from Service-Like Creep-Fatigue Experiments on Grade P92 Steel”, submitted to Data in Brief. Additional analyses of these datasets, as well as experimental findings and discussions are presented in “Creep-Fatigue of P92 in Service-Like Tests with Combined Stress- and Strain-Controlled Dwell Times”, submitted to International Journal of Fatigue. KW - Creep-fatigue KW - Stress relaxation KW - Dwell-Fatigue KW - Tempered martensite-ferritic steel PY - 2022 DO - https://doi.org/10.5281/zenodo.7198218 PB - Zenodo CY - Geneva AN - OPUS4-55995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens T1 - Binder Jetting of Advanced Ceramics N2 - The Binder Jetting BJ process is one of the most versatile additive manufacturing technologies in use. In this process a binder is locally jetted into a powder bed for the consolidation of a 3D structure, layer by layer. Basically, all materials which can be provided as a flowable powder and, thus, spreadable to a thin layer, can be processed. Metals, ceramics and polymers are processable, but also materials from nature, such as sand, wood sawdust and insect frass. Moreover, the BJ technology is adapted to large building volumes of some cubic meters easily. Besides these striking advantages, the manufacture of ceramic parts by BJ is still challenging, as the packing density of the powder bed is generally too low and the particle size of a flowable powder too large for a successful densification of printed parts in a subsequent sintering step to an advanced ceramic product. After an introduction of binder jetting in general and highlighting some examples, strategies for obtaining dense ceramic parts by BJ will be introduced. T2 - yCAM 2022 CY - Barcelona, Spain DA - 08.11.2022 KW - Additive Manufacturing KW - Ceramics PY - 2022 AN - OPUS4-59887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diener, S. A1 - Schubert, Hendrik A1 - Held, A. A1 - Katsikis, N. A1 - Günster, Jens A1 - Zocca, Andrea T1 - Influence of the dispersant on the parts quality in slurry-based binder jetting of SiC ceramics N2 - Binder jetting is establishing more and more in the ceramic industry to produce large complex shaped parts. A parameter with a great impact on the quality of the parts is the binder–powder interaction. The use of ceramic slurries as feedstock for this process, such as in the layerwise slurry deposition–print technology, allows a great flexibility in the composition. Such slurries are typically composed of ceramic powder, water, and small amounts of various additives. The understanding of the effect of these components on the printing quality is thus essential for the feedstock development. Four models were developed regarding the impact of additives, such as dispersants on printing. These models were confirmed or rebutted by experiments performed for an SiC slurry system with two different concentrations of a dispersant and a commercial phenolic resin used as a binder. It is shown that for this system the influence of the dispersant on the curing behavior and the clogging of the pores by dispersant can be neglected. The redispersion of the dispersant after the curing of the resin has no or only a minor effect. However, the wetting behavior determined by the surface energies of the system seem to be most crucial. In case the surface energy of the slurry additive is significantly lower than the surface energy of the binder, the strength of the green parts and the printing quality will be low. This was shown by inverse gas chromatography, contact angle measurement, rheological characterization, and mechanical tests with casted samples. KW - Additive Manufacturing KW - Binder Jetting KW - Layerwise slurry deposition KW - Silicon carbide KW - Wetting PY - 2022 DO - https://doi.org/10.1111/jace.18693 SN - 1551-2916 VL - 2022 SP - 1 EP - 15 PB - Wiley-Blackwell CY - Oxford AN - OPUS4-55542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea T1 - Combination of layerwise slurry deposition and binder jetting (lsd-print) for the additive manufacturing of advanced ceramic materials N2 - Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. Powder bed fusion and binder jetting especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders. In this context, the “layerwise slurry deposition” (LSD) has been developed as a layer deposition method which enables the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder layer. This offers high flexibility in the ceramic feedstock used, especially concerning material and particle size. The LSD technology can be combined with binder jetting to develop the so-called “LSDprint” process for the additive manufacturing of ceramics. The LSDprint technology combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing. In this presentation, the LSD process will be introduced and several examples of application ranging from silicate to high-performance ceramics will be shown. Recent developments towards the scale-up and industrialization of this process will be discussed, alongside future perspectives for the multi-material additive manufacturing. T2 - Shaping 8 CY - Dübendorf, Switzerland DA - 14.09.2022 KW - Additive Manufacturing KW - 3D printing KW - Ceramics PY - 2022 AN - OPUS4-56523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bender, R. A1 - Féron, D. A1 - Mills, D. A1 - Ritter, S. A1 - Bäßler, Ralph A1 - Bettge, Dirk A1 - de Graeve, I. A1 - Dugstad, A. A1 - Grassini, S. A1 - Hack, T. A1 - Halama, M. A1 - Han, E.-H. A1 - Harder, T. A1 - Hinds, G. A1 - Kittel, J. A1 - Krieg, R. A1 - Leygraf, C. A1 - Martinelli, L. A1 - Mol, A. A1 - Neff, D. A1 - Nilsson, J.-O. A1 - Odnevall, I. A1 - Paterson, S. A1 - Paul, S. A1 - Prošek, T. A1 - Raupach, M. A1 - Revilla, R. I. A1 - Ropital, F. A1 - Schweigart, H. A1 - Szala, E. A1 - Terryn, H. A1 - Tidblad, J. A1 - Virtanen, S. A1 - Volovitch, P. A1 - Watkinson, D. A1 - Wilms, M. A1 - Winning, G. A1 - Zheludkevich, M. T1 - Corrosion challenges towards a sustainable society N2 - A global transition towards more sustainable, affordable and reliable energy systems is being stimulated by the Paris Agreement and the United Nation's 2030 Agenda for Sustainable Development. This poses a challenge for the corrosion industry, as building climate‐resilient energy systems and infrastructures brings with it a long‐term direction, so as a result the long‐term behaviour of structural materials (mainly metals and alloys) becomes a major prospect. With this in mind “Corrosion Challenges Towards a Sustainable Society” presents a series of cases showing the importance of corrosion protection of metals and alloys in the development of energy production to further understand the science of corrosion, and bring the need for research and the consequences of corrosion into public and political focus. This includes emphasis on the limitation of greenhouse gas emissions, on the lifetime of infrastructures, implants, cultural heritage artefacts, and a variety of other topics. KW - Corrosion KW - Corrosion costs KW - Corrosion protection KW - Preventive strategies PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-554801 DO - https://doi.org/10.1002/maco.202213140 SN - 1521-4176 VL - 73 IS - 11 SP - 1730 EP - 1751 PB - Wiley-VCH CY - Weinheim AN - OPUS4-55480 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cestari, F. A1 - Yang, Y. A1 - Wilbig, Janka A1 - Günster, Jens A1 - Motta, A. A1 - Sglavo, V. T1 - Powder 3D printing of bone scaffolds with uniform and gradient pore sizes using cuttlebone-derived calcium phosphate and glass-ceramic N2 - The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45–100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 ◦C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells’ number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure. KW - Bioactivity KW - Cuttlefish KW - Biphasic calcium phosphate KW - Binder jetting KW - Scaffold geometry KW - Hausner ratio PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553627 DO - https://doi.org/10.3390/ma15155139 SN - 1996-1944 VL - 15 IS - 15 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-55362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rizzardi, Q. A1 - McElfresh, C. A1 - Sparks, G. A1 - Stauffer, D. A1 - Marian, J. A1 - Maaß, Robert T1 - Mild-to-wild plastic transition is governed by athermal screw dislocation slip in bcc Nb N2 - Plastic deformation in crystals is mediated by the motion of line defects known as dislocations. For decades, dislocation activity has been treated as a homogeneous, smooth continuous process. However, it is now recognized that plasticity can be determined by longrange correlated and intermittent collective dislocation processes, known as avalanches. Here we demonstrate in body-centered cubic Nb how the long-range and scale-free dynamics at room temperature are progressively quenched out with decreasing temperature, eventually revealing intermittency with a characteristic length scale that approaches the Burgers Vector itself. Plasticity is shown to be bimodal across the studied temperature regime, with conventional thermally-activated smooth plastic flow (‘mild’) coexisting with sporadic Bursts (‘wild’) controlled by athermal screw dislocation activity, thereby violating the classical Notion of temperature-dependent screw dislocation motion at low temperatures. An abrupt increase of the athermal avalanche component is identified at the critical temperature of the material. Our results indicate that plasticity at any scale can be understood in terms of the coexistence of these mild and wild modes of deformation, which could help design better alloys by suppressing one of the two modes in desired temperature Windows. KW - Plastic deformation KW - Microplastic stress KW - Intermittent microplasticity PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543927 DO - https://doi.org/10.1038/s41467-022-28477-4 VL - 13 IS - 1 SP - 1 EP - 9 PB - Nature AN - OPUS4-54392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tielemann, Christopher A1 - Reinsch, Stefan A1 - Maaß, Robert A1 - Deubener, J. A1 - Müller, Ralf T1 - Internal nucleation tendency and crystal surface energy obtained from bond energies and crystal lattice data N2 - We present an easy-to-apply method to predict structural trends in the internal nucleation tendency of oxide glasses. The approach is based on calculated crystal fracture surface energies derived from easily accessible diatomic bond energy and crystal lattice data. The applicability of the method is demonstrated on literature nucleation data for isochemically crystallizing oxide glasses. KW - Glass KW - Nucleation tendency KW - Fracture surface energy KW - Crystal lattice KW - Bond energy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548814 DO - https://doi.org/10.1016/j.nocx.2022.100093 SN - 2590-1591 VL - 14 SP - 1 EP - 5 PB - Elsevier B.V. AN - OPUS4-54881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günster, Jens T1 - Research and carrier in governmental research institute in Japan and Germany N2 - Being invited to Japan in 1996 as a Humboldt/STA was on of the most exciting things in my life. Not that it is on an absolute scale the most exciting thing still, but at that time, just after finalizing my PhD and thinking what is coming next, it was. KW - Networking PY - 2022 DO - https://doi.org/10.11470/oubutsu.91.2_115 SN - 0369-8009 VL - 91 IS - 2 SP - 115 EP - 117 PB - Gakkai CY - Tōkyō AN - OPUS4-54462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Bettge, Dirk T1 - Electrochemical behaviors of casing steel/mortar interface in CO2 saturated aquifer fluid N2 - To reveal the corrosion resistance of casing steel/mortar interface in CO2 injection condition, sandwich samples were prepared and exposed up to 20 weeks in aquifer fluid under 10 MPa and 60 °C. Cross section analysis revealed the crevice corrosion as main mechanism instead of pitting corrosion, which would be expected to happen in the extremely high Chloride concentration. Detailed analysis using EDS line scan shown the slow diffusion of Chloride, suggesting why pitting did not happen after 20 weeks. To mimic the passivated steel surface, the steel coupon was passivated in simulated pore solution having pH 13.5 for 42 days. The passivated coupon was further exposed to NGB solution for 28 days. Electrochemical characterization was performed along the exposure processes to reveal the change in impedance, indicating the corrosion resistance of steel casing/mortar interface. T2 - EUROCORR 2022 CY - Berlin, Germany DA - 28.08.2022 KW - Corrosion KW - CO2 quality KW - Pipeline network KW - CCS PY - 2022 SP - 859 EP - 865 PB - European Federation of Corrosion AN - OPUS4-55622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena T1 - Laser beam melting additive manufacturing at μ-gravity N2 - In-space manufacturing (ISM) provides the opportunity to manufacture and repair critical components on future human spaceflight missions. For explorations to Mars and beyond, ISM is a key strategy not only due to the long travel distances and high costs of supply from earth but also to be able to safely work in space for years. Human spaceflight is still dependent on shipments from earth that can fail for several reasons. ISM is a valuable alternative to ensure the timely and safe resupply of space missions. With additive manufacturing (AM) technologies, components are built directly from a 3D computer-aided-design (CAD) model which offers the advantages of freedom of design and the production of complex and ready-to-use parts. A virtual tool box with 3D models in space or the supply of information instead of components from earth to space can strongly benefit future missions. For industrial use, most research has focused on laser based additive manufacturing processes such as laser beam melting (LBM) where metallic powder particles are spread into a uniform powder bed and melted by a laser to the desired shape. In the absence of gravity, the handling of metal powders, which is essential for the process, is challenging. We present an evolution of an AM system, where a gas flow throughout the powder bed is applied to stabilize the powder bed. This is needed to compensate for the missing gravitational forces in microgravity experiments on parabolic flight campaigns. The system consists of a porous building platform acting as a filter for the fixation of metal particles in a gas flow. It is driven by reduced pressure established by a vacuum pump underneath the platform. The system creates a drag force that directs the particles towards the porous building platform, similar to the effect of the gravitational force. The AM system with its gas-flow-assisted powder deposition has been tested in several parabolic flight campaigns, and stainless-steel powder has successfully been processed during microgravity conditions. Different powder recoating mechanisms have been investigated to assess the homogeneous distribution of the powder as well as the attachment of the next layer to the powder bed. These mechanisms included different container designs with parallel double blades and with a V-shape at the bottom, and a roller recoating system. The samples presented are the first metal parts ever manufactured using LBM in μ-gravity. In addition to manufacturing in a μ-gravity environment, the experiments have shown the feasibility to manufacture components at different accelerations during the parabolic flight: hyper gravity (1.8 g), μ-gravity (< 0.01 g) and 1 g. Recent results will also be presented describing the application of this LBM setup in a parabolic flight campaign with mixed lunar, martian and µ-gravity acceleration, during which the processing of a lunar regolith simulant powder was tested. For ISM, the development and testing of the proposed AM system demonstrates that LBM can be considered a viable technology for the manufacturing of metal and ceramic parts in a μ-gravity or reduced-gravity environment. T2 - International Conference on Advanced Manufacturing CY - Online meeting DA - 07.03.2022 KW - μ-gravity KW - In-space manufacturing KW - Additive manufacturing KW - Laser beam melting KW - Microgravity KW - Stainless steel KW - Lunar regolith simulant PY - 2022 AN - OPUS4-54450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena T1 - Powder based Additive Manufacturing in Space N2 - Abstract of the event: 'The area of New Space is a vastly growing and dynamic field with a high innovative potential and many exciting ideas. After decades where activities in space were dominated and funded mainly by governmental agencies, a new industry is forming and new business models are being developed around ideas like satellite-based internet, space travel, space mining, geo-monitoring etc. For space applications, lightweight design is crucial to keep the costs at a minimum. This Innovation Day will introduce the field of New Space and present the variety of exciting opportunities that arise for composites based on their excellent lightweight potential.' Another research area is now arising in the field of 3D printing or additive manufacturing of fiber composite materials in space. At the event, we presented on the opportunities and our experiences of using a powder based additive manufacturing process for in-space manufacturing applications. T2 - CU Innovation Day - New opportunities and applications in space with composites CY - Online meeting DA - 29.03.2022 KW - μ-gravity KW - In-space manufacturing KW - Additive manufacturing KW - Microgravity KW - Powder PY - 2022 AN - OPUS4-54559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandić Lipińska, M. T1 - PAVER - Contextualizing laser sintering within a lunar technology roadmap N2 - The Global Exploration Strategy of the International Space Exploration Coordination Group (ISECG) describes a timeframe of 2020 and beyond with the ultimate aim to establish a human presence on Mars towards the 2040ies. The next steps lie on the Moon with a focus on the coming 10 years. Early lunar surface missions will establish a capability in support of lunar science and prepare and test mission operations for subsequent human exploration of Mars and long-duration human activities on the Moon. Given the extreme costs involved in the shipping of material from Earth, a prerequisite for future human exploration is the manufacturing of elements directly on the Moon’s surface. Unlike the equipment, which at the beginning will have to be brought from Earth, raw materials and energy could be available following the concept of In-Situ Resource Utilization. The ESA OSIP PAVING THE ROAD (PAVER) study investigates the use of a laser to sinter regolith into paving elements for use as roadways and launch pads thus mitigating dust issues for transport and exploration vehicles. The ESA-funded study examines the potential of using a laser (12 kW CO2 laser with spot beam up to 100 mm) for layer sintering of lunar and martian regolith powders to manufacture larger 3D elements and provide know-how for the automatic manufacture of paving elements in the lunar environment. The project contributes to the first step toward the establishment of a lunar base and will lead to the construction of equipment capable of paving areas and manufacturing 3D structures. PAVER project sets the starting point for an examination of the larger context of lunar exploration. Mission scenarios will look at different phases of lunar exploration: Robotic Lunar Exploration, Survivability, Sustainability, and Operational Phase. A proposed Technology Roadmap investigates the mission scenario and analyses how, and to which extent, laser melting/sintering will play a role in the various phases of exploration. The paper contextualizes laser sintering within selected mission scenarios and discusses the different kinds of infrastructure that can be produced at each phase of the mission. The outcome of the study includes the detailing of the TRL steps in the project and an outline of a timeline for the different elements. Covered aspects include terrain modelling such as operation pads, roadways, or towers, non-pressurized building structures to protect machinery, and habitat envelopes, to protect and shield humans against dust, micrometeoroids, and radiation. T2 - 73rd International Astronautical Congress (IAC) CY - Paris, France DA - 18.09.2022 KW - Additive manufacturing KW - ISRU KW - Infrastructure KW - Lunar habitat KW - Paving KW - Solar sintering PY - 2022 AN - OPUS4-56529 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Kuchenbecker, Petra A1 - Lindemann, Franziska T1 - Final report proficiency test LS BAM-5.5-2021: Measurement of the particle size distribution of ceramic powders by laser diffraction in accordance with ISO 13320 N2 - This is the final report on the proficiency test (PT) „Measurement of the particle size distribution of ceramic powders by laser diffraction”. The PT was organized by the Federal Institute for Materials Research and Testing (BAM), division 5.5 “Advanced technical ceramics”. The measurements took place from 12/2021 to 03/2022. The aim of the interlaboratory comparison was the proficiency assessment of the participating laboratories. Management and realization of PT were performed in accordance with DIN EN ISO/IEC 17043:2010. The basis of the harmonized measuring procedure and the instructions for the interlaboratory comparison was the standard ISO 13320:2020. The statistical analysis was performed in accordance with DIN ISO 13528:2020 by use of the software PROLab Plus (QuoData GmbH, Dresden, Germany). A group of 44 laboratories from 17 countries participated in the PT. Laser diffraction analyzers produced by 7 different manufacturers were used. The three test materials were commercial products. Overall, the measured characteristic values of the particle distributions (d10, d50 and d90) were in the size range between 0.5 and 25 μm. The final report contains all individual results in an anonymous way. KW - Proficiency test KW - Particle size KW - Laser light scattering PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548640 DO - https://doi.org/10.26272/opus4-54864 SP - 1 EP - 33 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-54864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stephan-Scherb, Christiane A1 - Lehmusto, Juho A1 - Falk, Florian A1 - Sobol, Oded A1 - Pint, Bruce T1 - Comprehensive insights into competitive oxidation/sulfidation reactions on binary ferritic alloys at high temperatures N2 - Interpreting high-temperature corrosion induced by mixed-gas atmospheres is challenging due to the different contributions of oxidizing gases. Here, a comprehensive study on the combined oxidation/sulfidation using label molecules is presented. Fe-Cr model alloys with 2 wt% and 9 wt% Cr were isothermally exposed using a volumetric mixture of 0.5%S16O2/27%H218O and 0.5%S16O2/7%H218O at 650 ◦C for 5 h and then characterized by secondary ion mass spectroscopy (SIMS). Additionally, the reactions were followed in-situ utilizing energy dispersive X-ray diffraction. The study showed that both S16O2 and H218O contribute to the oxidation of the alloys but to different extents depending on the Cr-content. KW - SEM KW - Steel KW - Iron KW - SIMS PY - 2022 DO - https://doi.org/10.1016/j.corsci.2022.110236 SN - 0010-938X VL - 203 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-58992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Fedelich, Bernard ED - Cailletaud, G. ED - Cormier, J. ED - Eggeler, G. ED - Maurel, V. ED - Nazé, L. T1 - Crystal plasticity models: dislocation based N2 - The large number of TEM investigations and the regular microstructure of single-crystal nickel-base superalloys has boosted the development of a number of physically motivated constitutive laws. In contrast to the more phenomenological models discussed in the next chapter, these models use dislocation densities as internal variables. Obvious advantages are that the computed densities can be compared to TEM observations and the Deformation mechanisms can be easier translated into mathematical equations. KW - Nickel-base superalloys KW - Creep KW - Plasticity PY - 2022 SN - 978-0-12-819357-0 SP - 401 EP - 427 PB - Elsevier Inc. ET - 1 AN - OPUS4-53436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard T1 - Experimental and analytical investigation of Low Cycle Fatigue Damage at notches in a polycrystalline Nickel base superalloy N2 - Turbine blades often contain cylindric holes used to generate an air film that protects the blade alloy from the hot gases. These cooling holes of diameter around one mm are drilled by laser through the thickness of the blades. Unfortunately, the resulting stress concentration and the drilling-induced damage are known to favor crack initiation from the holes. It is thus necessary to assess the impact of these cooling holes on the structural integrity of the blades. Since cracks initiate very readily, the fatigue life of the components is mainly controlled by the propagation of the cracks in the stress gradient induced by the holes. For this purpose, displacement controlled high-temperature LCF (Low-Cycle-Fatigue) tests were performed with center hole specimens of a coarse-grained Nickel base Superalloy. The tests were stopped after a defined load drop. In addition, crack propagation tests with Double Edge Notch specimens were performed. Moreover, specimens with different hole surface finishes were investigated, which showed a detrimental effect of the hole surface roughness. In parallel, an evaluation of the LCF tests based on a fracture mechanics-based model (Madia et al., Eng. Fract. Mech., 2018) has been applied. Thereby, the specimen life is controlled by the crack propagation time until failure. Crack growth is controlled by a modified NASGRO equation accounting for large-scale yielding and a progressive build-up of crack closure. The initial crack size has been derived from the measurements of defects around the borehole. A reasonable agreement between predicted and measured lifetimes is observed if one keeps in mind the large uncertainty regarding the effective shape of the cracks. T2 - 23rd European Conference on Fracture CY - Funchal, Madeira, Portugal DA - 27.06.2022 KW - Nickel-base superalloys KW - Notches KW - LCF PY - 2022 AN - OPUS4-55338 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Rhode, Michael A1 - Boerner, Andreas A1 - Saliwan Neumann, Romeo A1 - Schneider, M. A1 - Laplanche, G. T1 - Influence of machining on the surface integrity of high- and medium-entropy alloys N2 - High- and medium-entropy alloys (HEAs) are a quite new class of materials. They have a high potential for applications from low to high temperatures due to the excellent combination of their structural properties. Concerning their application as components; processing properties, such as machinability, have hardly been investigated so far. Hence, machinability analyses with a focus on the influence of the milling process and its basic parameters (cutting speed, feed per cutting edge) on the resulting surface integrity of specimens from an equiatomic high- (CoCrFeMnNi) and a medium- (CoCrNi) entropy alloy have been carried out. A highly innovative milling process with ultrasonic assistance (USAM) was compared to conventional milling processes. Recent studies have shown that USAM has a high potential to significantly reduce the mechanical load on the tool and workpiece surface during milling. In this study, the basic machining and ultrasonic parameters were systematically varied. After machining, the surface integrity of the alloys was analyzed in terms of topography, defects, subsurface damage, and residual stresses. It was observed that USAM reduces the cutting forces and increases the surface integrity in terms of lower tensile residual stresses and defect density near the surfaces for the CoCrFeMnNi alloy. It was shown that the cutting forces and the metallurgical influence in the sub surface region are reduced by increasing the cutting speed and reducing the feed rate per cutting edge. With the CoCrNi alloy, the tool revealed severe wear. As a result, for this alloy no influence of the parameters on the machinability could be determined. KW - High Entropy Alloy KW - Medium Entropy Alloys KW - Ultrasonic assited machining PY - 2022 DO - https://doi.org/10.1016/j.matchemphys.2021.125271 SN - 0254-0584 VL - 275 SP - 125271 PB - Elsevier B.V. AN - OPUS4-53606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - Wang, L. T1 - Elastic energy of multi-component solid solutions and strain origins of phase stability in high-entropy alloys N2 - The elastic energy of mixing for multi-component solid solutions is derived by generalizing Eshelby's sphere-in-hole model. By surveying the dependence of the elastic energy on the chemical composition and lattice misfit, we derive a lattice strain coefficient λ*. Studying several high-entropy alloys and superalloys, we propose that most solid solution multi-component alloys are stable when λ*<0.16, generalizing the Hume-Rothery atomic-size rule for binary alloys. We also reveal that the polydispersity index δ, frequently used for describing strain in multi-component alloys, directly represents the elastic energy e with e=qδ², q being an elastic constant. Furthermore, the effects of (i) the number and (ii) the atomic-size distribution of constituting elements on the phase stability of high-entropy alloys were quantified. The present derivations and discussions open for richer considerations of elastic effects in high-entropy alloys, offering immediate support for quantitative assessments of their thermodynamic properties and studying related strengthening mechanisms. KW - Ordering KW - High-entropy alloys KW - Alloy design KW - Strain energy KW - Phase stability PY - 2022 DO - https://doi.org/10.1016/j.scriptamat.2021.114226 SN - 1359-6462 VL - 206 SP - 1 EP - 6 PB - Elsevier CY - Amsterdam AN - OPUS4-53427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard T1 - Experimental and analytical investigation of high temperature fatigue crack growth at notches in a polycrystalline Nickel base superalloy N2 - The scatter of fatigue crack growth data can become significant for coarse grained materials. By using a probabilistic description of crack propagation as the foundation of a lifetime prediction model, lifetime scatter of laboratory specimens can be reproduced. However, the lifetime of real components is subjected to additional scattering factors such as surface condition or uncertainty regarding direction and shape of emerging cracks. These factors need to be addressed in order to exploit the advantages of probabilistic description, i.e. the reduction of unnecessary conservatisms. High temperature LCF (Low-Cycle-Fatigue) tests were performed with center hole specimens of a coarse-grained Nickel base Superalloy. In addition, crack propagation tests with Double Edge Notch specimens were performed. A procedure to detect the shape of the starting crack that combines the potential drop method and induction thermography was developed. The geometry and the number of notches were varied. Moreover, specimen with different hole surface finishes were investigated, which showed a detrimental effect of the roughness of the hole surface. The results have been compared to predictions of a probabilistic tool for the estimation of lcf lifetime that has been calibrated beforehand on laboratory specimens with and without notches. In parallel, a fracture mechanics-based lifetime model was developed, which includes the initial crack size as a critical parameter. Thereby, the influence of the large grain size (>1mm), and the shape of the starting crack at the notch were considered. Acknowledgements The investigations are conducted as part of the joint research program COOREFLEX-Turbo in the frame of AG Turbo. The work is supported by Siemens AG and the Bundesministerium für Wirtschaft und Technologie (BMWi) as per resolution of the German Federal Parliament under grant number 03ET7071E. T2 - Low Cycle Fatigue 9 CY - Berlin, Germany DA - 21.06.2022 KW - Nickel-base superalloys KW - Notches KW - LCF PY - 2022 AN - OPUS4-55335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Darvishi Kamachali, Reza T1 - Grain Boundary Segregation Design using CALPHAD-integrated Phase-Field Modelling N2 - A main source of current challenges in materials science and engineering is the ever-increasing complexity in materials chemistry and processing resulting in complex microstructures, making the assessment of process-microstructure-property-performance relations difficult, even unmanageable. Here the computational materials science is facing the same situation. In this talk, I share a viewpoint that the complexities in chemistry, processing and microstructures can be circumscribed by integrating existing knowledges of bulk thermodynamics and kinetics to the unknown thermodynamics and kinetics of microstructure elements. To this end, I discuss several successful examples on grain boundary segregation engineering how this scientific advance can be conducted. A roadmap is proposed, beginning to form on generalizing the concept of phase diagrams. T2 - ICAMS Advance Discussions: Advanced models for microstructure evolution – process-microstructure-property relationships CY - Bochum, Germany DA - 26.10.2022 KW - Microstructure Design KW - CALPHAD KW - Phase-Field Simulations KW - Machine Learning KW - Phase Diagrams PY - 2022 AN - OPUS4-56348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Darvishi Kamachali, Reza T1 - CALPHAD integrated density-based phase diagrams and opening possibilities for grain boundary engineering N2 - Engineering grain boundaries demands a quantitative description of both their segregation and specific phase behavior. Recently I have proposed a density-based model for grain boundary thermodynamics that enables CALPHAD integrated derivation of grain boundary phase diagrams, broadly applied now in studying various alloys. Combining this model with experimental investigations, in this talk, new aspects of interfacial segregation and phase transformation revealed in polycrystalline alloys are discussed. The effect of elastic interaction on grain boundary phase behavior is incorporated. We consider Al alloys and novel high-entropy alloys and discuss a general strategy for grain boundary engineering. T2 - 18th Discussion Meeting on Thermodynamics of Alloys (TOFA) CY - Krakow, Poland DA - 12.09.2022 KW - CALPHAD KW - Microstructure Design KW - Materials Modelling PY - 2022 AN - OPUS4-56044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena T1 - How will we explore, work, and live on the moon? N2 - 3D-printed landing pads on the moon: Paving the road for large area sintering of lunar regolith. A prerequisite for lunar exploration and beyond is the manufacturing of objects directly on the moon, given the extreme costs involved in the shipping of material from Earth. Looking at processes, raw materials, and energy sources, equipment will certainly have to be brought from Earth at the beginning. Available on the moon are lunar regolith as raw material and the sun as an energy source. One of the first steps towards the establishment of a lunar base is the creation of infrastructure elements, such as roads and landing pads. We’ll introduce you to the ESA-project PAVER that demonstrates the sintering and melting of lunar regolith simulant material to produce large scale 3D printed elements that could be used during human and robotic lunar explorations. T2 - Berlin Science Week CY - Online meeting DA - 09.11.2022 KW - Additive manufacturing KW - Lunar regolith simulant KW - EAC-1A KW - Space exploration PY - 2022 UR - https://www.youtube.com/watch?v=StfLuVhKkUE AN - OPUS4-56377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Corrosion Effects on Materials Considered for CC(U)S Applications N2 - Commercially available carbon steels are suitable for compression and pipelines as long as moisture content and impurities are limited. (water 50 to 100 ppmv, SO2 and NO2 ca. 100 ppmv) Corrosion rates increase with increasing water content. (0.2 – 20 mm/a) Condensation of acids and therefore droplet formation is always possible, even at low water contents. A low SO2 content within the CO2-stream might be more important than a low water content. Cr13-steels showed a general susceptibility to shallow pitting and pitting. So, they seem to be not suitable for CCUS applications. Low alloyed steels showed better corrosion behavior (predictable uniform corrosion). For direct contact with saline aquifer fluids only high alloyed steels shall be used. T2 - EFC Webinar CY - Online Meeting (Chongqing, China) DA - 18.05.2022 KW - Corrosion KW - CO2 quality KW - CO2 KW - CCS KW - CCU KW - Pipeline PY - 2022 AN - OPUS4-54854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Electrochemical behaviors of casing steel/mortar interface in CO2 saturated aquifer fluid N2 - To reveal the corrosion resistance of casing steel/mortar interface in CO2 injection condition, sandwich samples were prepared and exposed up to 20 weeks in aquifer fluid under 10 MPa and 60 °C. Cross section analysis revealed the crevice corrosion as main mechanism instead of pitting corrosion despite very high concentration of Cl in NGB. EDS element line scan analysis of the 20-week-exposed metal/mortar coupon showed Chloride distribution, which still not reached the metal/mortar interface, explaining no pitting was observed. It was confirmed that FeCO3 cannot protect the steel surface in CO2 saturated NGB. To verify the protective possibility of passivation happened on casing steel/mortar interface, simulated pore solution was synthesized and used to passivate the steel for 42 days. OCP and EIS confirmed the formation of passive layer. The 42 day passivated layer was broken during the first minute of exposure in CO2 saturated NGB. However, due to high concentration of Ca2+, a new carbonate CaCO3 dense layer was formed, increased the corrosion resistance of steel surface. T2 - EUROCORR 2022 CY - Berlin, Germany DA - 28.08.2022 KW - Corrosion KW - Geothermal KW - CO2 KW - Mortar PY - 2022 AN - OPUS4-55621 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wilbig, Janka A1 - Waske, Anja A1 - Günster, Jens A1 - Widjaja, Martinus Putra A1 - Neumann, C. A1 - Clozel, M. A1 - Meyer, A. A1 - Ding, J. A1 - Zhou, Z. A1 - Tian, X. T1 - Challenges in the Technology Development for Additive Manufacturing in Space N2 - Instead of foreseeing and preparing for all possible scenarios of machine failures, accidents, and other challenges arising in space missions, it appears logical to take advantage of the flexibility of additive manufacturing for “in-space manufacturing” (ISM). Manned missions into space rely on complicated equipment, and their safe operation is a great challenge. Bearing in mind the absolute distance for manned missions to the Moon and Mars, the supply of spare parts for the repair and replacement of lost equipment via shipment from Earth would require too much time. With the high flexibility in design and the ability to manufacture ready-to-use components directly from a computer-aided model, additive manufacturing technologies appear to be extremely attractive in this context. Moreover, appropriate technologies are required for the manufacture of building habitats for extended stays of astronauts on the Moon and Mars, as well as material/feedstock. The capacities for sending equipment and material into space are not only very limited and costly, but also raise concerns regarding environmental issues on Earth. Accordingly, not all materials can be sent from Earth, and strategies for the use of in-situ resources, i.e., in-situ resource utilization (ISRU), are being envisioned. For the manufacturing of both complex parts and equipment, as well as for large infrastructure, appropriate technologies for material processing in space need to be developed. KW - Additive manufacturing KW - Space KW - Process PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549204 DO - https://doi.org/10.1016/j.cjmeam.2022.100018 SN - 2772-6657 VL - 1 IS - 1 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-54920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea T1 - Additive Manufacturing of advanced ceramics by layerwise slurry deposition and binder jetting (LSD-print) N2 - Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. Powder bed fusion and binder jetting especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder layer. This offers high flexibility in the ceramic feedstock used, especially concerning material and particle size. The LSD technology can be combined with binder jetting to develop the so-called “LSDprint” process for the additive manufacturing of ceramics. The LSDprint technology combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing. In this presentation, the LSD process will be introduced and several examples of application ranging from silicate to high-performance ceramics will be shown. Recent developments towards the scale-up and industrialization of this process will be discussed, alongside future perspectives for the multi-material additive manufacturing. T2 - Ceramics in Europe 2022 CY - Krakow, Poland DA - 10.07.2022 KW - Layerwise slurry deposition KW - Laser induced slipcasting KW - Additive Manufacturing KW - Ceramics PY - 2022 AN - OPUS4-55543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Zocca, Andrea T1 - Dense Powder Beds for the Additive Manufacturing of Ceramics N2 - Regarding feedstocks for the additive manufacturing (AM) of ceramics, two features are most critical in classical powder based AM processes: a high particle packing density (typically >50% TD) must be achieved with very fine particles (typically submicron) in order to ensure sufficient sintering activity. Three innovative approaches will be introduced to overcome this problem: 1. Layer wise slurry deposition: The use of water based ceramic slurries as feedstock for the additive manufacture of ceramics has many advantages which are not fully exploit yet. In the layerwise slurry deposition (LSD) process a slurry with no or low organic content is repetitively spread as thin layers on each other by means of a doctor blade. During the deposition, the ceramic particles settle on the previously deposited and dried material to form thin layers with a high packing density (55-60%). The LSD therefore shares aspects both of tape casting and slip casting. The LSD differentiates from the classical powder-based AM layer deposition, which typically achieves with a flowable coarse grained powder a low packing density (35-50%) only, consequently hindering the ability of sintering ceramic parts to full density. The LSD is coupled with the principles of selective laser sintering (SLS) or binder jetting, to generate novel processes which take advantage of the possibility of achieving a highly dense powder-bed. 2. Laser induced slip casting: Contrary to the LSD process, which requires drying of each individual layer, the direct interaction of ceramic slurries with intense laser radiation, for the laser induced slip casting (LIS), is a promising approach for the additive manufacture of voluminous parts. 3. Gas flow assisted powder deposition: By the application of a vacuum pump a gas flow is realized throughout the powder bed. This gas flow stabilizes the powder bed and results into an enhanced flowability and packing density of the powder during layer deposition. The presentation will provide a detailed discussion of potentialities and issues connected to the mentioned technologies and will describe the most recent developments in their application to technical ceramics. T2 - SmatMade 2022 CY - Osaka, Japan DA - 25.10.2022 KW - Additive Manufacturing KW - Advanced ceramics PY - 2022 AN - OPUS4-59886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rizzardi, Q. A1 - Derlet, P. M. A1 - Maaß, Robert T1 - Intermittent microplasticity in the presence of a complex microstructure N2 - We demonstrate the gradual shift from scale-free intermittent microplasticity to a scale-dependent behavior via the introduction of a variety of microstructural features within the Al-Cu binary alloy system. As long as the obstacles to dislocation motion remain shearable, the statistics of intermittent microplasticity has fat-tailed contributions. The introduction of incoherent precipitates leads to a complete transition from scale-free powerlaw scaling to an exponential and scale-dependent distribution. These results demonstrate how non-Gaussian interactions survive across different microstructures and further suggest that characteristic microstructural length scales and obstacle pinning-strengths are of secondary importance for the intermittency statistics, as long as dislocations can shear their local environment. KW - Scale-dependent behavior KW - Al-Cu binary alloy system PY - 2022 DO - https://doi.org/10.1103/PhysRevMaterials.6.073602 SN - 2475-9953 VL - 6 IS - 7 SP - 1 EP - 9 PB - American Physical Society AN - OPUS4-55387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallis, Theophilus A1 - Darvishi Kamachali, Reza T1 - Grain boundary structural variations amplify segregation transition and stabilize co-existing spinodal interfacial phases N2 - Grain boundaries (GBs)’s role in determining the functional and mechanical properties of polycrystalline materials is inscribed in both their structure and chemistry. Upon solute segregation, the structure and composition of a GB can change concurrently. We study the co-evolution of GB’s structure and segregation by enhancing the density-based phase-field model to account for the in-plane structural variations in the GB. Significant mutual coupling is revealed between the GB’s chemical and structural states during Mn segregation in Fe-Mn alloys. We found that the structural degrees of freedom in a GB (the ability of the GB structure to respond to the chemical variation) amplifies Mn segregation transition, even when the GB structure stays unchanged. When the GB structure is not uniform, that is the usual case, the coupling between GB structure and segregation evolution also enables the spinodally formed low- and high-Mn phases (upon segregation transition) to co-exist within the GB region. These findings explain the stabilizing mechanism of pronounced interfacial segregation fluctuations, experimentally evidenced in Fe-Mn GBs, and give new insights on the structural sensitivity of GBs’ segregation phenomena and the mutual chemo-structural interplay. KW - Grain boundary engineering KW - Segregation engineering KW - Grain boundary structure KW - Fe-Mn steels PY - 2022 DO - https://doi.org/10.1016/j.actamat.2022.118446 SN - 1359-6454 VL - 242 PB - Elsevier Ltd. AN - OPUS4-56160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maximilian, Thuy A1 - Spyrantis, Alexander A1 - Böhning, Martin A1 - Niebergall, Ute A1 - Maaß, Robert T1 - Spatially resolved roughness exponent in polymer fracture N2 - The fracture surface of slow and continuous crack propagation during environmental stress cracking of a semicrystalline polyethylene exhibits isotropic roughness exponents at the local scale but resolved across the macroscopic fracture surface a clear position dependence is found. The spatially resolved roughness exponent admits values in the range between 0.1 and 0.4, demonstrating nontrivial exponents in the small length-scale regime. Instead, they vary across the fracture surface according to the stress-state distribution, which suggests that the exponents are intimately linked to the locally dominating dissipation processes during craze cracking. KW - Plasticity KW - Fracture KW - Material failure KW - Mechanical deformation PY - 2022 DO - https://doi.org/10.1103/PhysRevMaterials.6.L090601 VL - 6 IS - 9 SP - 1 EP - 7 PB - American Physical Society CY - USA, Maryland AN - OPUS4-55797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shimada, Y. A1 - Ikeda, Yuki A1 - Yoshida, K. A1 - Sato, M. A1 - Chen, J. A1 - Du, Y. A1 - Inoue, K. A1 - Maaß, Robert A1 - Nagai, Y. A1 - Konno, T. T1 - In situ thermal annealing transmission electron microscopy of irradiation induced Fe nanoparticle precipitation in Fe–Si alloy N2 - The typical experimental conditions inside a transmission electron microscope (TEM), such as ultra-high vacuum, high-energy electron irradiation, and surface effects of ultrathin TEM specimens, can be the origin of unexpected microstructural changes compared with that of bulk material during in situ thermal-annealing experiments. In this paper, we report on the microstructural changes of a Fe–15%Si alloy during in situ TEM annealing, where, in its bulk form, it exhibits an ordering transformation from D03 to B2 at 650 °C. Using a heating-pot type double tilt holder with a proportional–integral–differential control system, we observed the precipitation of α-Fe both at the sample surface and inside the sample. Surface precipitates formed via surface diffusion are markedly large, several tens of nm, whereas precipitates inside the specimen, which are surrounded by Fe-poor regions, reach a maximum size of 20 nm. This unexpected microstructural evolution could be attributed to vacancies on Si sites, which are induced due to high-energy electron irradiation before heating, as well as enhanced thermal diffusion of Fe atoms. KW - In situ thermal-annealing experiment KW - Microstructural changes of a Fe Si alloy KW - Microstructural evolution PY - 2022 DO - https://doi.org/10.1063/5.0070471 SN - 0021-8979 VL - 131 IS - 16 SP - 1 EP - 8 PB - AIP Publishing AN - OPUS4-54728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maaß, Robert T1 - The Federal Institute of Materials Research and Testing (BAM) – 150 Years of Enabling Scientific and Technological Breakthrough N2 - BAM! This issue of Advanced Engineering Materials celebrates 150 years of scientific and technical research at the interface between academia, industry and politics. Rooted in 1871 at the birth of the German Empire and at that time located in simple basements and barracks, the institutional development began around mechanical metallurgy of iron and steel and represents today a diverse portfolio of fore-front research that orients itself along tomorrow's societal challenges and long-term research horizons. KW - 150 Years KW - Adolf Martens PY - 2022 DO - https://doi.org/10.1002/adem.202200648 VL - 24 IS - 6 SP - 1 EP - 3 PB - Wiley-VCH GmbH AN - OPUS4-55388 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derlet, P. M. A1 - Maaß, Robert T1 - Optimally rejuvenated model binary glasses N2 - Using the creation relaxation algorithm developed for the atomistic modeling of the high-dose irradiation limit of crystalline systems, we explore the limits of the structural rejuvenation of a highly excited model binary glass. This high-energy athermal amorphous structure exhibits a direct transition to homogeneous plastic flow and a microstructure that is largely insensitive to this flow, being characterized by a porous system-spanning network of minimally frustrated structural motifs. The observed homogeneous plasticity is mediated by the same string-like structural excitations, which mediate structural relaxation and microplasticity at finite temperature in more relaxed structures. This highly rejuvenated structural asymptote is not far from the structural state of regions, which have experienced athermal shear localization in more relaxed samples, suggesting an optimally rejuvenated glassy structure will always be limited by that produced by shear localization. KW - Metallic glasses KW - Creation-relaxation algorithm KW - Shear PY - 2022 DO - https://doi.org/10.1103/PhysRevMaterials.6.125604 VL - 6 IS - 12 SP - 1 EP - 13 PB - American Physical Society AN - OPUS4-56741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandić Lipińska, M. A1 - Davenport, R. A1 - Imhof, A. B. A1 - Waclavicek, R. A1 - Fateri, M. A1 - Meyer, Lena A1 - Gines-Palomares, J. C. A1 - Zocca, Andrea A1 - Makaya, A. A1 - Günster, Jens T1 - PAVER - Contextualizing laser sintering within a lunar technology roadmap N2 - The Global Exploration Strategy of the International Space Exploration Coordination Group (ISECG) describes a timeframe of 2020 and beyond with the ultimate aim to establish a human presence on Mars towards the 2040ies. The next steps lie on the Moon with a focus on the coming 10 years. Early lunar surface missions will establish a capability in support of lunar science and prepare and test mission operations for subsequent human exploration of Mars and long-duration human activities on the Moon. Given the extreme costs involved in the shipping of material from Earth, a prerequisite for future human exploration is the manufacturing of elements directly on the Moon’s surface. Unlike the equipment, which at the beginning will have to be brought from Earth, raw materials and energy could be available following the concept of In-Situ Resource Utilization. The ESA OSIP PAVING THE ROAD (PAVER) study investigates the use of a laser to sinter regolith into paving elements for use as roadways and launch pads thus mitigating dust issues for transport and exploration vehicles. The ESA-funded study examines the potential of using a laser (12 kW CO2 laser with spot beam up to 100 mm) for layer sintering of lunar and martian regolith powders to manufacture larger 3D elements and provide know-how for the automatic manufacture of paving elements in the lunar environment. The project contributes to the first step toward the establishment of a lunar base and will lead to the construction of equipment capable of paving areas and manufacturing 3D structures. PAVER project sets the starting point for an examination of the larger context of lunar exploration. Mission scenarios will look at different phases of lunar exploration: Robotic Lunar Exploration, Survivability, Sustainability, and Operational Phase. A proposed Technology Roadmap investigates the mission scenario and analyses how, and to which extent, laser melting/sintering will play a role in the various phases of exploration. The paper contextualizes laser sintering within selected mission scenarios and discusses the different kinds of infrastructure that can be produced at each phase of the mission. The outcome of the study includes the detailing of the TRL steps in the project and an outline of a timeline for the different elements. Covered aspects include terrain modelling such as operation pads, roadways, or towers, non-pressurized building structures to protect machinery, and habitat envelopes, to protect and shield humans against dust, micrometeoroids, and radiation. T2 - 73rd International Astronautical Congress (IAC) CY - Paris, France DA - 18.09.2022 KW - Additive manufacturing KW - Solar sintering KW - ISRU KW - Infrastructure KW - Lunar habitat KW - Paving PY - 2022 SP - 1 EP - 9 AN - OPUS4-56519 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens T1 - Laser beam melting additive manufacturing at μ-gravity N2 - At the Workshop "Neutron and Synchrotron Monitoring in Aerospace Advanced Manufacturing" at the Institute of Materials Physics in Space, German Aerospace Center (DLR) in Cologne, we presented on the opportunities and our experiences of using a powder based additive manufacturing process for in-space manufacturing applications in microgravity. T2 - Workshop 'Neutron and Synchrotron Monitoring in Aerospace Advanced Manufacturing' CY - Cologne, Germany DA - 11.08.2022 KW - Additive manufacturing KW - In-space manufacturing KW - Microgravity KW - μ-gravity KW - Laser beam melting KW - Advanced manufacturing KW - Aerospace KW - Process monitoring PY - 2022 AN - OPUS4-56521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Riechers, Birte A1 - Zocca, Andrea A1 - Rosalie, Julian A1 - Maaß, Robert A1 - Sturm, Heinz A1 - Günster, Jens T1 - Entering a new dimension in powder processing for advanced ceramics shaping N2 - Filigree structures can be manufactured via two-photon-polymerization (2PP) operating in the regime of non-linear light absorption. For the first time it is possible to apply this technique to the powder processing of ceramic structures with a feature size in the range of the critical defect size responsible for brittle fracture and, thus, affecting fracture toughness of high-performance ceramics. In this way, tailoring of advanced properties can be achieved already in the shaping process. Traditionally, 2PP relies on transparent polymerizable resins, which is diametrically opposed to the usually completely opaque ceramic resins and slurries. Here we present a transparent and photocurable suspension of nanoparticles (resin) with very high mass fractions of yttria-stabilized zirconia particles (YSZ). Due to the extremely well dispersed nanoparticles, scattering of light can be effectively suppressed at the process-relevant wavelength of 800 nm. Sintered ceramic structures with a resolution of down to 500 nm were obtained. Even at reduced densities of 1 to 4 g/cm³, the resulting compressive strength with 4,5 GPa is equivalent or even exceeding bulk monolithic yttria stabilized zirconia. A ceramic metamaterial is born, where the mechanical properties of yttria stabilized zirconia are altered by changing geometrical parameters and gives access to a new class of ceramic materials. KW - Two-photon-polymerization KW - Ceramics KW - Powder processing KW - Transparency KW - Meta material KW - Yttria stabilized zirconia PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564598 DO - https://doi.org/10.1002/adma.202208653 SN - 1521-4095 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -