TY - JOUR A1 - Belli, R. A1 - Hurle, K. A1 - Schürrlein, J. A1 - Petschelt, A. A1 - Werbach, K. A1 - Peterlik, H. A1 - Rabe, Torsten A1 - Mieller, Björn A1 - Lohbauer, U. T1 - Relationships between fracture toughness, Y2O3 fraction and phase content in modern dental Yttria-doped zirconias N2 - The relationship between fracture toughness and Yttria content in modern zirconia ceramics was revised. For that purpose, we evaluated here 10 modern Y2O3-stabilized zirconia (YSZ) materials currently used in biomedical applications, namely prosthetic and implant dentistry. The most relevant range between 2-5 mol% Y2O3 was addressed by selecting from conventional opaque 3 mol% YSZ up to more translucent compositions (4-5 mol% YSZs). A technical 2YSZ was used to extend the range of our evaluation. The bulk mol% Y2O3 concentration was measured by X-Ray Fluorescence Spectroscopy. Phase quantification by Rietveld refinement considered two tetragonal phases or an additional cubic phase. A first-account of the fracture toughness (KIc) of the pre-sintered blocks is given, which amounted to 0.4 – 0.7 MPa√m. In the fully-densified state, an inverse power-law behavior was obtained between KIc and bulk mol% Y2O3 content, whether using only our measurements or including literature data, challenging some established relationships. A linear relationship between KIc and the fraction of the transformable t-phase was established within the range of 30–70 vol%. KW - Ceramics KW - Dental KW - Zirconia KW - Fracture toughness KW - X-ray-diffraction KW - Power law PY - 2021 DO - https://doi.org/10.1016/j.jeurceramsoc.2021.08.003 VL - 41 IS - 15 SP - 7771 EP - 7782 PB - Elsevier Ltd. AN - OPUS4-53107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Busch, R. A1 - Tielemann, Christopher A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Patzig, C. A1 - Krause, M. A1 - Höche, T. T1 - Sample preparation for analytical scanning electron microscopy using initial notch sectioning N2 - A novel method for broad ion beam based sample sectioning using the concept of initial notches is presented. An adapted sample geometry is utilized in order to create terraces with a well-define d step in erosion depth from the surface. The method consists of milling a notch into the surface, followed by glancing-angle ion beam erosion, which leads to preferential erosion at the notch due to increased local surface elevation. The process of terrace formation can be utilized in sample preparation for analytical scanning electron microscopy in order to get efficient access to the depth-dependent microstructure of a material. It is demonstrated that the method can be applied to both conducting and non-conducting specimens. Furthermore, experimental parameters influencing the preparation success are determined. Finally, as a proof-of-concept, an electron backscatter diffraction study on a surface crystallized diopside glass ceramic is performed, where the method is used to analyze orientation dependent crystal growth phenomena occurring during growth of surface crystals into the bulk. KW - 3D etching KW - Ion beam erosion Sectioning KW - EBSD KW - Sample preparation KW - Analytical scanning electron microscopy KW - SEM KW - Glass Ceramic KW - Glass KW - Diopsid PY - 2021 DO - https://doi.org/10.1016/j.micron.2021.103090 SN - 0968-4328 VL - 150 PB - Elsevier B.V. AN - OPUS4-53075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plarre, Rüdiger A1 - Zocca, Andrea A1 - Spitzer, Andrea A1 - Benemann, Sigrid A1 - Gorbushina, Anna A1 - Li, Y. A1 - Waske, Anja A1 - Funk, Alexander A1 - Wilgig, Janka A1 - Günster, Jens T1 - Searching for biological feedstock material: 3D printing of wood particles from house borer and drywood termite frass N2 - Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer (EHB) and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the EHB Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of woodbased structures in a layer wise fashion using the Binder Jetting printing process. The Quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a Hausner Ratio HR = 1.1 with ρBulk = 0.67 g/cm3 and ρTap = 0.74 g/cm3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing. KW - 3D printing KW - X-ray tomographic KW - SEM micrography KW - Drywood termite PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521517 DO - https://doi.org/10.1371/journal.pone.0246511 VL - 16 IS - 2 SP - e0246511 AN - OPUS4-52151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chi, J. A1 - Agea Blanco, B. A1 - Bruno, Giovanni A1 - Günster, Jens A1 - Zocca, Andrea T1 - Self-Organization Postprocess for Additive Manufacturingin Producing Advanced Functional Structure and Material N2 - Additive manufacturing (AM) is developing rapidly due to itsflexibility in producing complex geometries and tailored material compositions. However, AM processes are characterized by intrinsic limitations concerning their resolution and surface finish, which are related to the layer-by-layer stacking process. Herein, a self-organization process is promoted as an approach to improve surface quality and achieve optimization of 3D minimal surface lightweight structures. The self-organization is activated after the powder bed 3D printing process via local melting, thereby allowing surface tension-driven viscous flow.The surface roughness Ra (arithmetic average of the roughness profile) could bedecreased by a factor of 1000 and transparent lenses and complex gyroid structures could be produced for demonstration. The concept of self-organization is further elaborated by incorporating external magnetic fields to intentionally manipulate magnetic particles, which are mixed with the polymer before printing and self-organization. This concept can be applied to develop programmable materials with specific microtextures responding to the external physical conditions. KW - Additive Manufacturing KW - Self-organization KW - Triply Periodical Minimal Surface PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540588 DO - https://doi.org/10.1002/adem.202101262 VL - 24 IS - 6 SP - 1 EP - 8 PB - Wiley VCH AN - OPUS4-54058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Rehmer, Birgit A1 - Haubrich, J. A1 - Avila, Luis A1 - Schoenstein, F. A1 - Serrano Munoz, Itziar A1 - Requena, G. A1 - Bruno, Giovanni T1 - Separation of the impact of residual stress and microstructure on the fatigue performance of LPBF Ti-6Al-4V at elevated temperature N2 - Manufacturing defects, high residual stress (RS), and microstructures affect the structural integrity of laser powder bed fusion (LPBF) Ti-6Al-4V. In this study, the individual effect of these factors on fatigue performance at elevated temperature (300 °C) was evaluated. Material in as-built condition and subjected to post-processing, including two heat treatments and hot isostatic pressing, was investigated. It was found that in the absence of tensile RS, the fatigue life at elevated temperature is primary controlled by the defects; and densification has a much stronger effect than the considered heat treatments on the improvement of the mechanical performance. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Fatigue performance KW - Computed tomography PY - 2021 DO - https://doi.org/10.1016/j.ijfatigue.2021.106239 SN - 0142-1123 VL - 148 SP - 106239 PB - Elsevier Ltd. AN - OPUS4-52369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ta, N. A1 - Bilal, M. U. A1 - Häusler, I. A1 - Saxena, A. A1 - Lin, Y.-Y. A1 - Schleifer, F. A1 - Fleck, M. A1 - Glatzel, U. A1 - Skrotzki, Birgit A1 - Darvishi Kamachali, Reza T1 - Simulation of the θ′ Precipitation Process with Interfacial Anisotropy Effects in Al-Cu Alloys N2 - The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ′-phase (Al2Cu) in Al-1.69 at.% Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipitate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additional incorporation of an anisotropic interfacial mobility in conjunction with the elastic anisotropy result in substantially larger aspect ratios of the precipitates closer to the experimental observations. The anisotropy of the interfacial energy shows comparably small effect on the precipitate’s aspect ratio but changes the interface’s shape at the rim. The effect of the chemo-mechanical coupling, i.e., the composition dependence of the elastic constants, is studied as well. We show that the inverse ripening phenomenon, recently evidenced for δ’ precipitates in Al-Li alloys (Park et al. Sci. Rep. 2019, 9, 3981), does not establish for the θ′ precipitates. This is because of the anisotropic stress fields built around the θ′ precipitates, stemming from the precipitate’s shape and the interaction among different variants of the θ′ precipitate, that disturb the chemo-mechanical effects. These results show that the chemo-mechanical effects on the precipitation ripening strongly depend on the degree of sphericity and elastic isotropy of the precipitate and matrix phases. KW - Aging KW - Phase-field simulation KW - Interfacial anisotropy KW - Chemo-mechanical coupling KW - Precipitation KW - Elasticity KW - θ′-(Al2Cu) precipitate phase PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522672 DO - https://doi.org/10.3390/ma14051280 VL - 14 IS - 5 SP - 1280 PB - MDPI AN - OPUS4-52267 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhou, X. A1 - Darvishi Kamachali, Reza A1 - Boyce, B.L. A1 - Clark, B.G. A1 - Raabe, D. A1 - Thompson, G.B. T1 - Spinodal Decomposition in Nanocrystalline Alloys N2 - For more than half a century, spinodal decomposition has been a key phenomenon in considering the formation of secondary phases in alloys. The most prominent aspect of the spinodal phenomenon is the lack of an energy barrier on its transformation pathway, offering an alternative to the nucleation and growth mechanism. The classical description of spinodal decomposition often neglects the influence of defects, such as grain boundaries, on the transformation because the innate ability for like-atoms to cluster is assumed to lead the process. Nevertheless, in nanocrystalline alloys, with a high population of grain boundaries with diverse characters, the structurally heterogeneous landscape can greatly influence the chemical decomposition behavior. Combining atom-probe tomography, precession electron diffraction and density-based phase-field simulations, we address how grain boundaries contribute to the temporal evolution of chemical decomposition within the miscibility gap of a Pt-Au nanocrystalline system. We found that grain boundaries can actually have their own miscibility gaps profoundly altering the spinodal decomposition in nanocrystalline alloys. A complex realm of multiple interfacial states, ranging from competitive grain boundary segregation to barrier-free low-dimensional interfacial decomposition, occurs with a dependency upon the grain boundary character. KW - Density-based Thermodynamics KW - Nanocrystalline alloys KW - Spinodal decomposition KW - Defects engineering PY - 2021 DO - https://doi.org/10.1016/j.actamat.2021.117054 VL - 215 SP - 117054 PB - Elsevier Ltd. AN - OPUS4-52918 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, C. A1 - Ikeda, Yuki A1 - Maaß, Robert T1 - Strain-dependent shear-band structure in a Zr-based bulk metallic glass N2 - This work presents strong evidence for structural damage accumulation as a function of shear strain admitted by shear bands in a Zr-based bulk metallic glass. Analyzing the shear-band structure of shear- band segments that experienced shear strains covering four orders of magnitude with high-angle annular dark field transmission electron microscopy (HAADF-STEM) reveals strongly scattered data with on overall trend of increasing local volume dilatation with increasing shear strain. Locally, however, a variety of trends is observed, which underlines the strong heterogeneity of structural damage in shear bands in metallic glasses. KW - Transmission electron microscopy KW - Metallic glass KW - Shear bands KW - Shear-band structure KW - Shear strain PY - 2021 DO - https://doi.org/10.1016/j.scriptamat.2020.08.030 VL - 190 SP - 75 EP - 79 PB - Elsevier Ltd. AN - OPUS4-52454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aristia, Gabriela A1 - Le, Quynh Hoa A1 - Nofz, Marianne A1 - Sojref, Regine A1 - Bäßler, Ralph T1 - Study of Al2O3 Sol-Gel Coatings on X20Cr13 in Artificial North German Basin Geothermal Water at 150 °C N2 - Al2O3 has been widely used as a coating in industrial applications due to its excellent chemical and thermal resistance. Considering high temperatures and aggressive mediums exist in geothermal systems, Al2O3 can be a potential coating candidate to protect steels in geothermal applications. In this study, γ-Al2O3 was used as a coating on martensitic steels by applying AlOOH sol followed by a heat treatment at 600 °C. To evaluate the coating application process, one-, two-, and three-layer coatings were tested in the artificial North German Basin (NGB), containing 166 g/L Cl−, at 150 °C and 1 MPa for 168 h. To reveal the stability of the Al2O3 coating in NGB solution, three-layer coatings were used in exposure tests for 24, 168, 672, and 1296 h, followed by surface and cross-section characterization. SEM images show that the Al2O3 coating was stable up to 1296 h of exposure, where the outer layer mostly transformed into boehmite AlOOH with needle-like crystals dominating the surface. Closer analysis of cross-sections showed that the interface between each layer was affected in long-term exposure tests, which caused local delamination after 168 h of exposure. In separate experiments, electrochemical impedance spectroscopy (EIS) was performed at 150 °C to evaluate the changes of coatings within the first 24 h. Results showed that the most significant decrease in the impedance is within 6 h, which can be associated with the electrolyte penetration through the coating, followed by the formation of AlOOH. Here, results of both short-term EIS measurements (up to 24 h) and long-term exposure tests (up to 1296 h) are discussed. KW - Al2O3 KW - Geothermal KW - Martensitic steels KW - Behmite KW - Corrosion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525551 DO - https://doi.org/10.3390/coatings11050526 SN - 2079-6412 VL - 11 IS - 5 SP - 526 PB - MDPI CY - Basel AN - OPUS4-52555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Camin, B. A1 - Hansen, L. A1 - Chyrkin, A. A1 - Nolze, Gert T1 - Synchrotron Sub-μ X-ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel-Base Superalloy and Nickel after Annealing at 1250 °C N2 - Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel-base superalloy CMSX-10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening ƴ'-phase ist partially dissolved. The porosity is studied by X-ray sub-μ tomography with a spatial resolution of about 0.35³ μm³ at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. It is found that depending on the distance from the interface the Kirkendall pores take different shapes: octahedral, rounded pyramidal, drop shaped, dendritic, pear shaped, and joint shapes. Such a variety of pore morphologies indicates a complex multistage process of porosity nucleation and growth under vacancy supersaturation of different degrees. The experimental findings are interpreted on the basis of the results of diffusion modeling. It is shown that the kinetics of porosity growth is essentially influenced by the dissolution of the ƴ'-phase. KW - Diffusion KW - Nickel alloys KW - Porous materials KW - Synchrotron radiations KW - Three-dimensional tomographies PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521476 DO - https://doi.org/10.1002/adem.202001220 VL - 23 IS - 4 SP - 1220 PB - Wiley Online Library AN - OPUS4-52147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert A1 - Winkelmann, A. A1 - Cios, G. A1 - Tokarski, T. T1 - Tetragonality mapping of martensite in high-carbon steel by EBSD N2 - The locally varying tetragonality in martensite grains of a high-carbon steel (1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD) with a spatial resolution in the order of 100 nm. Compared to spatially integrating X-ray diffraction, which yielded an average tetragonality fo c/a=1.05, the EBSD measurements in the scanning electron microscope allowed to image a local variation of the lattice papameter ration c/a in the range of 1.02 ≤ c/a ≤ 1.07. The local variation of tetragonality is confirmed by two different EBSD data analysis approaches based on the fitting of simulated to experimental EBSD patterns. The resulting EBSD-based tetragonality maps are pointing to a complex interaction of carbon concentration and local lattice distortions during the formation process of martensitic structures. KW - EBSD KW - Martensite KW - Tetragonal distortion KW - Pattern matching PY - 2021 DO - https://doi.org/10.1016/j.matchar.2021.111040 VL - 175 SP - 111040 PB - Elsevier Inc. AN - OPUS4-52343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plichta, T. A1 - Sirjovona, V. A1 - Zvonek, M. A1 - Kalinka, Gerhard A1 - Cech, V. T1 - The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite N2 - High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer Matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load. KW - Mechanical properties KW - Plasma nanocoatings KW - Glass fibre KW - Polymer composite KW - Short-beam strength KW - Interfacial shear strength KW - Work of adhesion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521844 DO - https://doi.org/10.3390/polym13040593 VL - 13 IS - 4 SP - 593 PB - MDPI CY - Basel,Schweiz AN - OPUS4-52184 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jürgens, Maria A1 - Sonntag, Nadja A1 - Olbricht, Jürgen A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - The effect of dwell times on the thermomechanical fatigue life performance of grade P92 steel at intermediate and low strain amplitudes N2 - Results of an extended TMF test program on grade P92 steel in the temperature range of 620 °C - 300 °C, comprising in-phase (IP) and out-of-phase (OP) tests, partly performed with symmetric dwells at Tmax/Tmin, are presented. In contrast to previous studies, the low-strain regime is also illuminated, which approaches flexible operation in a power plant with start/stop cycles. At all strain amplitudes, the material performance is characterized by continuous cyclic softening, which is retarded in tests at lower strains but reaches similar magnitudes in the course of testing. In the investigated temperature range, the phase angle does not affect fatigue life in continuous experiments, whereas the IP condition is more detrimental in tests with dwells. Fractographic analyses indicate creep-dominated and fatigue-dominated damage for IP and OP, respectively. Analyses of the (micro)hardness distribution in the tested specimens suggest an enhanced microstructural softening in tests with dwell times for the low- but not for the high-strain regime. To rationalize the obtained fatigue data, the fracture-mechanics-based D_TMF concept, which was developed for TMF life assessment of ductile alloys, was applied. It is found that the D_TMF parameter correlates well with the measured fatigue lives, suggesting that subcritical growth of cracks (with sizes from a few microns to a few millimeters) governs failure in the investigated range of strain amplitudes. KW - 9-12%Cr steel KW - Thermomechanical fatigue KW - Symmetric dwell periods KW - Low strain KW - Parametric modeling PY - 2021 DO - https://doi.org/10.1016/j.msea.2020.140593 VL - 805 SP - 140593 PB - Elsevier B.V. AN - OPUS4-52374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falk, Florian A1 - Sobol, Oded A1 - Stephan-Scherb, Christiane T1 - The impact of the microstructure of Fe-16Cr-0.2C on high-temperature oxidation – sulphidation in SO2 N2 - This study elucidates the impact of the microstructure of Fe-16Cr-0.2C on oxide layer formation at 650 ◦C in Ar-0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. The samples were characterised in detail from microstructural and chemical perspectives using scanning electron microscopy (SEM), X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microstructural modification of the alloy by heat-treatment was advantageous. It was found that Cr-carbides support chromia formation and reduce sulphidation when their area fraction is low and diameter is small. KW - Steel KW - Iron KW - SIMS KW - SEM KW - High temperature corrosion KW - Oxidation KW - Sulphidation PY - 2021 DO - https://doi.org/10.1016/j.corsci.2021.109618 VL - 190 SP - 109618 PB - Elsevier Ltd. AN - OPUS4-53001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sprengel, Maximilian A1 - Ulbricht, Alexander A1 - Evans, Alexander A1 - Kromm, Arne A1 - Sommer, Konstantin A1 - Werner, Tiago A1 - Kelleher, J. A1 - Bruno, Giovanni A1 - Kannengießer, Thomas T1 - Towards the optimization of post-laser powder bed fusion stress-relieve treatments of stainless steel 316L N2 - This study reports on the stress relaxation potential of stress-relieving heat treatments for laser powder bed fused 316L. The residual stress is monitored non-destructively using neutron diffraction before and after the heat treatment. Moreover, the evolution of the microstructure is analysed using scanning electron microscopy. The results show, that a strong relaxation of the residual stress is obtained when applying a heat treatment temperature at 900°C. However, the loss of the cellular substructure needs to be considered when applying this heat treatment strategy. KW - Residual stress KW - Additive manufacturing KW - Neutron diffraction KW - Projekt AGIL - Alterung additiv gefertigter metallischer Materialien und Komponenten PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536045 DO - https://doi.org/10.1007/s11661-021-06472-6 SN - 1543-1940 VL - 52 IS - 12 SP - 5342 EP - 5356 PB - Springer CY - Boston AN - OPUS4-53604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tokarski, T. A1 - Nolze, Gert A1 - Winkelmann, A. A1 - Rychlowski, L. A1 - Bala, P. A1 - Cios, G. T1 - Transmission Kikuchi diffraction: The impact of the signal-to-noise ratio N2 - Signal optimization for transmission Kikuchi diffraction (TKD) measurements in the scanning electron microscope is investigated by a comparison of different sample holder designs. An optimized design is presented, which uses a metal shield to efficiently trap the electron beam after transmission through the sample. For comparison, a second holder configuration allows a significant number of the transmitted electrons to scatter back from the surface of the sample holder onto the diffraction camera screen. It is shown that the secondary interaction with the sample holder leads to a significant increase in the background level, as well as to additional noise in the final Kikuchi diffraction signal. The clean TKD signal of the optimized holder design with reduced background scattering makes it possible to use small signal changes in the range of 2% of the camera full dynamic range. As is shown by an analysis of the power spectrum, the signal-to-noise ratio in the processed Kikuchi diffraction patterns is improved by an order of magnitude. As a result, the optimized design allows an increase in pattern signal to noise ratio which may lead to increase in measurement speed and indexing reliability. KW - EBSD KW - SEM KW - Transmission Kikuchi diffraction KW - Sample holder PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531743 DO - https://doi.org/10.1016/j.ultramic.2021.113372 SN - 0304-3991 SN - 1879-2723 VL - 230 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-53174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Rouxel, T. A1 - Behrens, H. A1 - Deubener, J. A1 - Müller, Ralf T1 - Vacuum crack growth in alkali silicate glasses N2 - 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 the theoretical fracture surface energy estimated from chemical bond energies. Data analysis reveals significant deviations from this 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. KW - Silicate glass KW - Brittle fracture KW - Crack growth KW - Calculated intrinsic fracture toughness PY - 2021 DO - https://doi.org/10.1016/j.jnoncrysol.2021.121094 SN - 0022-3093 VL - 572 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-53144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derlet, P. A1 - Bocquet, H. A1 - Maaß, Robert T1 - Viscosity and transport in a model fragile metallic glass N2 - How thermally activated structural excitations quantitatively mediate transport and microplasticity in a model binary glass at the microsecond timescale is revealed using atomistic simulation. These local excitations, involving a stringlike sequence of atomic displacements, admit a far-field shear-stress signature and underlie the transport of free-volume and bond geometry. Such transport is found to correspond to the Evolution of a disclination network describing the spatial connectivity of topologically distinct bonding environments, demonstrating the important role of geometrical frustration in both glass structure and its underlying dynamics. KW - Metallic glass KW - Viscosity PY - 2021 DO - https://doi.org/10.1103/PhysRevMaterials.5.125601 SN - 2475-9953 VL - 5 SP - 1 EP - 7 PB - American Physical Society CY - College Park, MD AN - OPUS4-54152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Manzoni, Anna Maria A1 - Schneider, M. A1 - Laplanche, G. T1 - Welding of high-entropy alloys and compositionally complex alloys - an overview N2 - High-entropy alloys (HEAs) and compositionally complex alloys (CCAs) represent new classes of materials containing five or more alloying elements (concentration of each element ranging from 5 to 35 at. %). In the present study, HEAs are defined as single-phase solid solutions; CCAs contain at least two phases. The alloy concept of HEAs/CCAs is fundamentally different from most conventional alloys and promises interesting properties for industrial applications (e.g., to overcome the strength-ductility trade-off). To date, little attention has been paid to the weldability of HEAs/CCAs encompassing effects on the welding metallurgy. It remains open whether welding of HEAs/CCAs may lead to the formation of brittle intermetallics and promote elemental segregation at crystalline defects. The effect on the weld joint properties (strength, corrosion resistance) must be investigated. The weld metal and heat-affected zone in conventional alloys are characterized by non-equilibrium microstructural evolutions that most probably occur in HEAs/CCAs. The corresponding weldability has not yet been studied in detail in the literature, and the existing information is not documented in a comprehensive way. Therefore, this study summarizes the most important results on the welding of HEAs/CCAs and their weld joint properties, classified by HEA/CCA type (focused on CoCrFeMnNi and AlxCoCrCuyFeNi system) and welding process. KW - High-entropy alloy KW - Compositionally complex alloy KW - Welding KW - Properties KW - Review PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527068 DO - https://doi.org/10.1007/s40194-021-01110-6 SP - 1 EP - 15 PB - Springer Nature AN - OPUS4-52706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Treninkov, И. A A1 - Petrushin, N. V. A1 - Epishin, А. I. A1 - Svetlov, I. L. A1 - Nolze, Gert A1 - Elyutin, E. S. T1 - ЭКСПЕРИМЕНТАЛЬНОЕ ОПРЕДЕЛЕНИЕ ТЕМПЕРАТУРНОЙ ЗАВИСИМОСТИ СТРУКТУРНО-ФАЗОВЫХ ПАРАМЕТРОВ НИКЕЛЕВОГО ЖАРОПРОЧНОГО СПЛАВА T1 - Experimental determination of temperature dependence of structural-phase parameters of nickel-based superalloy N2 - Методом рентгеноструктурного анализа в интервале температур 18—1150 °С определены температурные зависимости периодов кристаллических решеток γ- и γ'-фаз, их размерно-го несоответствия (мисфит) и объемной доли γ'-фазы экспериментального монокристал-лического жаропрочного никелевого сплава. Определены диапазоны температур, в которых происходят интенсивные изменения структурно-фазовых характеристик исследованного сплава. KW - рентгеноструктурный анализ KW - высокие температуры KW - жаропрочные нике- левые сплавы KW - монокристалл KW - γ- и γ'-фазы, период кристаллической решетки PY - 2021 DO - https://doi.org/10.31044/1684-579x-2021-0-7-3-12 IS - 7 SP - 3 EP - 12 AN - OPUS4-53110 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -