TY - JOUR A1 - Scheuerlein, C. A1 - Andrieux, J. A1 - Michels, M. A1 - Lackner, F. A1 - Chiriac, R. A1 - Hagner, M. A1 - Di Michiel, M. A1 - Meyer, Christian A1 - Toche, F. ED - Foley, C. P. T1 - Effect of the fabrication route on the phase and volume changes during the reaction heat treatment of Nb3Sn superconducting wires N2 - Accelerator magnets that can reach magnetic fields well beyond the Nb-Ti performance limits are presently being built and developed, using Nb3Sn superconductors. This technology requires reaction heat treatment (RHT) of the magnet coils, during which Nb3Sn is formed from its ductile precursor materials (a “wind and react” approach). The Nb3Sn microstructure and microchemistry are strongly influenced by the conductor fabrication route, and by the Phase changes during RHT. By combining in situ differential scanning calorimetry, high Energy synchrotron x-ray diffraction, and micro-tomography experiments, we have acquired a unique data set that describes in great detail the phase and microstructure changes that take place during the processing of restacked rod process (RRP), powder-in-tube (PIT), and internal tin (IT) Nb3Sn wires. At temperatures below 450 ° the phase evolutions in the three wire types are similar, with respectively solid state interdiffusion of Cu and Sn, Cu6Sn5 formation, and Cu6Sn5 peritectic transformation. Distinct differences in phase evolutions in the wires are found when temperatures exceed 450 °C. The volume changes of the conductor during RHT are a difficulty in the production of Nb3Sn accelerator magnets. We compare the wire diameter changes measured in situ by dilatometry with the phase and void volume evolution of the three types of Nb3Sn wire. Unlike the Nb3Sn wire length changes, the wire diameter evolution is characteristic for each Nb3Sn wire type. The strongest volume increase, of about 5%, is observed in the RRP wire, where the main diameter increase occurs above 600 °C upon Nb3Sn formation. KW - Nb3Sn KW - Microstructure KW - Phase transformations KW - Volume changes KW - X-ray diffraction KW - Differential scanning calorimetry KW - Synchrotron micro-tomography PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505128 DO - https://doi.org/10.1088/1361-6668/ab627c VL - 33 IS - 3 SP - 034004 PB - IOP Publishing CY - Bristol (UK) AN - OPUS4-50512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Batahgy, A. A1 - Saiyah, A. A1 - Khafagi, S. A1 - Gumenyuk, Andrey A1 - Gook, S. A1 - Rethmeier, Michael T1 - Shielded metal arc welding of 9%Ni steel using matching ferritic filler metal N2 - Motivated by the tensile strength loss of 9%Ni steel arc welded joints made using Ni-based austenitic filler metals, the feasibility of maintaining the tensile strength using matching ferritic filler metal has been demonstrated. In comparison with shielded metal arc welded joint made using Ni-based austenitic electrode ENiCrMo-6, higher tensile strength comparable to that of the base metal was obtained using matching ferritic electrode. Besides, sufficient impact toughness energies with much lower mismatch were obtained for weld metal and heat-affected zone. Welded joint with a lower mechanical mismatching is of considerable importance for achieving acceptable combination of tensile strength and impact toughness.Abetter combination of These mechanical properties is ensured by applying a post weld heat treatment. KW - Mechanical mismatching KW - Mechanical properties KW - Microstructure KW - Austenitic welding electrode KW - Matching ferritic welding electrode PY - 2020 DO - https://doi.org/10.1080/13621718.2020.1846936 SN - 1362-1718 SP - 1 EP - 7 PB - Taylor & Francis AN - OPUS4-51835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Werder, Julia A1 - Fontana, P. A1 - Hoppe, Johannes A1 - Bilgin, S. A1 - Meng, Birgit ED - Serrat, C. ED - Casas, J. R. ED - Gibert, V. T1 - Composite Facade Elements with Self-Cleaning Surface made of Ultra-High-Performance Concrete (UHPC) N2 - In the framework of the European project H-House various concrete façade elements were developed with the aim to ensure a long service life by combining a very durable material with self-cleaning properties. The façade elements presented are made of a shell of UHPC filled with blocks of aerated autoclaved concrete as insulating material. Self-cleaning properties were realized amongst others by imprinting a microstructure into the surface during casting. The paper focuses on selected technological aspects of the manufacturing process of prototypes which had to be performed in two concreting sections. Furthermore the challenges faced when upscaling the self-cleaning properties are addressed and the strategy to assess the self-cleaning properties by measuring the contact and the roll-off angel is presented. The results show that a successfull upscalaing process requires detailed planning and that the best results can often be achieved with a moderate work effort or material use. T2 - XV International Conference on Durability of Building Materials and Components (DBMC 2020) CY - Online meeting DA - 20.10.2020 KW - Ultra-High-Performance Concrete KW - Facade Elements KW - Self-Cleaning Properties KW - Adhesive Pull-Strength KW - Microstructure KW - Architectural Concrete PY - 2020 SN - 978-84-121101-8-0 SP - 1289 EP - 1297 PB - International Center for Numerical Methods in Engineering (CIMNE) CY - Spain AN - OPUS4-51967 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lemiasheuski, Anton A1 - Bajer, Evgenia A1 - Oder, Gabriele A1 - Göbel, Artur A1 - Hesse, Rene A1 - Bettge, Dirk T1 - Development of an Automated 3D Metallography System (RASI) and its Application in Microstructure Analysis N2 - Many microstructural features exhibit non-trivial geometries, which can only be derived to a limited extent from two-dimensional images. E.g., graphite arrangements in lamellar gray cast iron have complex geometries, and the same is true for additively manufactured materials and three-dimensional conductive path structures. Some can be visualized using tomographic methods, but some cannot be due to weak contrast and/or lack of resolution when analyzing macroscopic objects. Classic metallography can help but must be expanded to the third dimension. The method of reconstructing three-dimensional structures from serial metallographic sections surely is not new. However, the effort required to manually assemble many individual sections into image stacks is very high and stands in the way of frequent application. For this reason, an automated, robot-supported 3D metallography system is being developed at BAM, which carries out the steps of repeated preparation and image acquisition on polished specimen. Preparation includes grinding, polishing and optionally etching of the polished surface. Image acquisition comprises autofocused light microscopic imaging at several magnification levels. The image stacks obtained are then pre-processed, segmented, and converted into 3D models, which in the result appear like microtomographic models, but with high resolution at large volume. Contrasting by classical chemical etching reveals structures that cannot be resolved using tomographic methods. The integration of further imaging and measuring methods into this system is underway. Some examples will be discussed in the presentation. T2 - Euromat 2023 CY - Frankfurt a. M., Germany DA - 04.07.2023 KW - Metallography KW - 3D Reconstruction KW - Roboter KW - Automation KW - Microstructure PY - 2023 AN - OPUS4-58202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaytsev, D. A1 - Funk, Alexander T1 - On the crack evolutional in human dentin under uniaxial compression imaged by high resolution tomography N2 - An observation of the fracture process in front of the crack tip inside a dentin sample by means of ex-situ X-ray computed tomography after uniaxial compression at different deformation values was carried out in this work. This ex-situ approach allowed the microstructure and fracturing process of human dentin to be observed during loading. No cracks are observed up to the middle part of the irreversible deformation in the samples at least visible at 0.4μm resolution. First cracks appeared before the mechanical stress reached the compression strength. The growth of the cracks is realized by connecting the main cracks with satellite cracks that lie ahead of the main crack tip and parallel its trajectory. When under the stress load the deformation in the sample exceeds the deformation at the compression strength of dentin, an appearance of micro-cracks in front of the main cracks is observed. The micro-cracks are inclined (~60°) to the trajectory of the main cracks. The further growth of the main cracks is not realized due to the junction with the micro-cracks; we assume that the micro-cracks dissipate the energy of the main crack and suppressed its growth. These micro-cracks serve as additional stress accommodations, therefore the samples do not break apart after the compression test, as it is usually observed under bending and tension tests. KW - Dentin KW - Crack evolution KW - Compression strength KW - Mechanical properties KW - Microstructure KW - Ex-situ X-ray computed tomography PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594810 DO - https://doi.org/10.18149/MPM.5152023_5 SN - 1605-8119 VL - 51 IS - 5 SP - 38 EP - 51 PB - Advanced Study Center CY - St. Petersburg AN - OPUS4-59481 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert A1 - Payton, E. A1 - Winkelmann, Aimo T1 - Advanced EBSD Pattern Interpretation through Iterative Post-Processing N2 - Since the BSE signal depends on many factors, like the chemistry of the phase and the acceleration voltage, the size and position of the detector array is (slightly) different from phase to phase so that an (iterative) post-processing of the stored patterns is highly recommended. The derived BSE signal can be used for phase assignment in high resolution and high speed maps when EBSD fails and/or EDS (energy dispersive spectroscopy) needs too much time for a suitable and parallel signal acquisition. KW - Electron backscatter diffraction KW - Phase identification KW - Microstructure KW - SEM PY - 2013 DO - https://doi.org/10.1017/S1431927613005631 VL - 19 IS - Suppl. 2 SP - 728 EP - 729 AN - OPUS4-37986 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Prospects of the metal magnetic memory technique N2 - Prospects and Restrictions of the Metal Magnetic Memory Technique T2 - 69th-IIW-Meeting CY - Melbourne, Australia DA - 12.07.2016 KW - Metal magnetic memory KW - Magnetic field KW - GMR sensor KW - Microstructure PY - 2016 AN - OPUS4-38133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietrich, D. A1 - Nolze, Gert A1 - Mehner, T. A1 - Nickel, D. A1 - Lampke, T. T1 - EDS/EBSD studies and HR-EBSD pattern analysis on pre-Inca ceramic fragments recovered during San José de Moro Archaeology Program N2 - Pre-Inca civilizations like the coastal cultures Moche and Nazca (Early Intermediate) and the inland culture Wari (Middle Horizon) were agrarian societies which supported indigenous elites of impressive wealth, power, and organization. With the expansion of the Wari Empire, the polychrome style and technique of Nazca propagated to the other cultures. High status burials, most of the Late Moche Fine Line ceramics and a large corpus of ceramics with Wari-derived decoration have been recovered in San José de Moro since 1991. The degree of transfer of procedures in this highly interactive scenario is of special interest: is there a limitation to decoration or is it adopted by the local potters also regarding the formulation of the ceramic bodies? In this context the relative amount, size and type of incorporated non-plastic inclusions as temper are important. T2 - The 16th European Microscopy Congress 2016 CY - Lyon, France DA - 28.08.2016 KW - EBSD KW - EDX KW - Ceramic KW - Phase distribution KW - Microstructure KW - Texture KW - Phase identification KW - SEM PY - 2016 DO - https://doi.org/10.1002/9783527808465.EMC2016.4462 SP - 4462 PB - John Wiley & Sons AN - OPUS4-37740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Petrushin, N. V. A1 - Link, T. A1 - Nolze, Gert A1 - Loshchinin, Yu. V. A1 - Gerstein, G. T1 - Thermal stability of the structure of a heat-resistant cobalt alloy hardened with intermetallic γ'-phase precipitates N2 - The thermal stability of the microstructure of a heat-resistant cobalt alloy, which consists of a γ solid solution strengthened with γ'-phase precipitates, has been studied. The temperature behavior of the dissolution of the hardening γ' phase and the kinetics of its coarsening at 700 and 800°C have been determined. It is found that, during prolonged annealing at 800°C, the γ' → β phase transformation occurs. KW - Superalloy KW - Microstructure KW - Hardening KW - Electron backscatter diffraction KW - TEM PY - 2016 DO - https://doi.org/10.1134/S0036029516040078 SN - 0036-0295 VL - 2016 IS - 4 SP - 286 EP - 291 PB - Pleiades Publishing AN - OPUS4-37768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nolze, Gert T1 - Microstructure characterization of the Treysa meteorite N2 - Microstructure descripton of heat-affected zone, fusion crust and main metal of the Treysa iron using scanning electron microscopy, EBSD and EDS. T2 - 8. Deutsches Meteoriten Kolloquium, CY - Zella Willingshausen, Germany DA - 02.04.2016 KW - Electron backscatter diffraction KW - EDX KW - Light microscopy KW - Microstructure KW - Oxidation PY - 2016 DO - https://doi.org/10.13140/RG.2.1.3387.8161 AN - OPUS4-37769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - NbC-based cermets: influence of secondary carbide addition and metal binder N2 - Full densification of Fe, Co and Ni bonded NbC based cermet’s was achieved by pressure less liquid phase sintering in vacuum for one hour at 1420°C. The hardness and toughness of the NbC matrix cermet’s can be mainly tailored by the binder composition and secondary carbide additions. Ni binder based NbC cermet’s allow the combination of high hardness and improved toughness. The addition of lesser amounts of VC/Cr3C2 in a NbC partially substituted WC-Co cemented carbide increased significantly the hardness in combination with a moderate fracture toughness. T2 - International Symposium on Wear Resistant Alloys for the Mining and Processing Industry CY - Sao Paulo, Brazil DA - 04.05.2015 KW - Niobium carbide KW - Hardmetal KW - Cemented carbide KW - Sintering KW - Grain growth KW - Microstructure KW - Hardness KW - Fracture toughness PY - 2018 SN - 978-0-692-05382-9 SP - 521 EP - 534 AN - OPUS4-44206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sommer, Konstantin T1 - Microstructure characterization of additive produced parts N2 - Due to the advantages of additive manufacturing (AM), it has been increasingly integrated into many industrial sectors. The application of AM materials for safety-critical parts requires the detailed knowledge about their microstructure stability under thermo-mechanical or mechanical load and knowledge on ageing process mechanisms. Ageing processes are characterized by change of the material microstructure that is to be initially investigated. This work deals with the Investigation of 316L stainless steel manufactured by selective laser melting (SLM). Describing Parameters must be defined and applied on the microstructure of these materials in their initial state and after loads were applied. The findings of this work form the basis for the investigation of AM material ageing. T2 - FEMS Junior EUROMAT 2018 CY - Budapest, Hungary DA - 08.07.2018 KW - Additive manufacturing KW - Selective laser melting KW - 316L KW - Material characterization KW - Microstructure PY - 2018 AN - OPUS4-47176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wäsche, Rolf T1 - Niobium carbide, a new cermet material with excellent properties N2 - Niobium carbide is a ceramic material which can be used with excellent results to replace tungsten carbide with cobalt binder. Furthermore, it might be manufactured by classic ceramic technologies and even colloidal processing. To achieve high toughness and strength, it is necessary to have a perfect mix of hard phase and binder, which is mainly achieved by ball milling. Mechanical and physical properties as well as results on different tribological and application-oriented machining tests are presented. The results have been compared with results obtained with NbC grades with Co and Fe3Al binders as well as with pure binderless hot-pressed NbC and SPS sintered Nb2O5. T2 - ICCCI 2018 - 6th Int. Conf. on the Characterization and Control of Interfaces for High Quality Advanced Materials and 54th Summer Symposium on Powder Technology CY - Kurashiki, Japan DA - 09.07.2018 KW - Niobium carbide KW - Cermet KW - Microstructure KW - Properties PY - 2018 AN - OPUS4-45643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - El-Batahgy, A. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Effect of laser-beam and hybrid-laser-arc welding parameters and filler metal on microstructure and mechanical properties of thick heat-treated steel X8ni9+Qt640 for cryogenic service N2 - The present research work encloses results of experimental investigations of the interaction between welding process parameters for laser-beam and hybrid-laser-arc as well as type of the filler metal and the achievable mechanical properties of the weld joints on steel grade X8Ni9+QT640 for cryogenic service containing 9% nickel. The results obtained contribute to the development and conversion in the industrial practice a new laser beam-based welding technology for the automated manufacturing of facilities for the liquefaction, storage and the transport of natural gases (LNG facilities). The results show, that the martensitic microstructure of the laser weld metal including low amount of retained austenite not exceeding 3.5% leads to the relatively low V-notch impact energy. The remarkable heterogeneity in the chemical composition of the weld metal through the weld thickness could be recognized in the case of hybrid-laser-arc welding with ERNiCrMo-3 austenitic filler metal, what also led to insufficient impact toughness of the weld metall. The most promising results could be achieved by using 11%Ni filler wire, which is similar to the base metal and provides a homogeneous microstructure with uniform distribution of Ni through the weld seam. It is remarkable, that a correlation between Charpy impact toughness and wire feeding speed and respectively process heat input exists. The highest toughness values were 134±58 J at -196C. The both laser as well as laser-hybrid welds passed the tensile test. The failure stress of 720±3 MPa with a fracture location in the base material was achieved for all samples tested. T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials CY - Aswan, Egypt DA - 19.11.2018 KW - Hybrid-laser-arc welding KW - Laser-beam welding, KW - Cryogenic steel KW - Microstructure KW - Tensile strength PY - 2018 SP - W-29, 1 EP - 10 AN - OPUS4-46738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian T1 - Microstructural investigations of an Al-2618 alloy N2 - Results of Microstructural investigations of an Al-2618 alloy are summrised and discussed. T2 - FVV Arbeitskreissitzung CY - Berlin, Germany DA - 13.05.2015 KW - Aluminium alloy KW - Transmission electron microscopy KW - Microstructure KW - Degradation PY - 2015 AN - OPUS4-42197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - NbC grain growth control and mechanical properties of Ni bonded NbC cermets prepared by vacuum liquid phase sintering N2 - The current study reports on the effect of the sintering temperature and secondary carbide (VC, Mo2C and TiC) and Mo additions on the NbC grain growth, microstructure evolution as well as concomitant Vickers hardness (HV30) and fracture toughness of Ni-bonded NbC cermets. KW - Cermet KW - Niobium carbide KW - Sintering KW - Microstructure KW - Mechanical properties PY - 2018 DO - https://doi.org/10.1016/j.ijrmhm.2017.12.013 SN - 0263-4368 VL - 72 SP - 63 EP - 70 PB - Elsevier Science CY - Amsterdam AN - OPUS4-43582 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weise, Frank A1 - von Werder, Julia A1 - Manninger, Tanja A1 - Maier, Bärbel A1 - Fladt, Matthias A1 - Simon, Sebastian A1 - Gardei, Andre A1 - Höhnel, Desirée A1 - Pirskawetz, Stephan A1 - Meng, Birgit T1 - A multiscale and multimethod approach to assess and mitigate concrete damage due to alkali-silica reaction N2 - Alkali-silica reaction (ASR) is a chemical reaction within concrete which can lead over time to cracking and spalling. Due to the complexity of the problem, it still causes damage to concrete constructions worldwide. The publication aims to illustrate the interdisciplinary research of the German Federal Institute for Materials Research and Testing (BAM) within the last 20 years, considering all aspects of ASR topics from the macro to the micro level. First, methods for characterization and assessment of ASR risks and reaction products used at BAM are explained and classified in the international context. Subsequently the added value of the research approach by combining different, preferably nondestructive, methods across all scales is explained using specific examples from a variety of research projects. Aspects covered range from the development of new test-setups to assess aggregate reactivity, to analysis of microstructure and reaction products using microscopical, spectroscopical and X-ray methods, to the development of a testing methodology for existing concrete pavements including in-depth analysis of the visual damage indicator and the de-icing salt input using innovative testing techniques. Finally, research regarding a novel avoidance strategy that makes use of internal hydrophobization of the concrete mix is presented. KW - Mitigation strategies KW - Concrete KW - Damage analysis KW - Alkali silica reaction KW - Road pavement KW - Accelerated testing KW - Non-destructive testing KW - Microstructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:101:1-2022052515100075090235 DO - https://doi.org/10.1002/adem.202101346 SN - 1527-2648 VL - 24 IS - 6 SP - 1 EP - 36 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick T1 - Utilization of an ultra sound atomizer for spray granulation of oxide ceramic fine powder N2 - Spray drying based granulation processes aim for flowable granules neither containing voids nor hard shells thus leading to a homogenous microstructure in the green and sinter bodies without strength reducing large pores. The increase of the specific surface area due to the utilization of finer powders as raw materials makes the production of granules of demanded quality more sophisticated. Innovations regarding additives as well as process engineering are therefore required. While conventional spray granulation processes of ceramic materials are based on rotational, one stream or two stream nozzles for nebulization, the investigations in the ZIM project concentrate on the applicability of an ultra sound atomizer unit. A spray dryer comprised of the aforementioned ultra sound atomization unit implemented in a commercial spray dryer (Niro, Denmark) was used as test system. Potential advantages of the ultra sound nebulization are investigated for model systems of alumina, zirconia and a ZTA composite while focusing on solids content, yield, pressability and granule properties (size, size distribution, flowability, shape and microstructure) as well as the final sinter body properties (density, microstructure and flexural strength). First ultra sound spray drying experiments yielded granules with excellent processability. Spray drying of identical slurries, as before tested and optimized for a two stream nozzle atomization process, resulted in a more suitable size distribution for dry pressing (less particles below 20 µm) and a higher yield. Furthermore, sinter bodies produced of ultra sound granules seem to have less large pores and a more homogenous microstructure T2 - 92. Jahrestagung der deutschen keramischen Gesellschaft CY - Berlin, Germany DA - 20.03.2017 KW - Ceramics KW - Spray drying KW - Ultra sound KW - Atomization KW - Microstructure PY - 2017 AN - OPUS4-39588 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Steppan, Enrico T1 - Influence of microalloy design on HAZ toughness of S690QL steel N2 - Three high strength Nb-, Ti- and Ti+V- bearing S690QL steels were welded to investigate and compare the effects of microalloy addition on HAZ toughness. Charpy V notch impact tests from three microalloyed welds under different cooling rates have been performed. Fractographic examination shows that several factors including large-sized grain, upper bainite or hard second phase, interact to determine the brittle fracture mode and impaired toughness of Nb bearing weld at high heat input. In contrast to this reduced toughness, Ti bearing welds exhibits satisfied toughness regardless of at a fast or slow cooling rate as a result of limited austenite grain and refined favourable intragranular acicular ferrite structure. Moreover, in the case of such refined structure as matrix, TiN particles are found to be irrelevant to the fracture process and crystallographic misorientation results also confirms that high angle boundaries between fine ferrites plates provide much effective barrier for crack propagation and contribute to improved toughness. T2 - 69th IIW Annual Assembly and International Conference CY - Melbourne, Australia DA - 10.07.2016 KW - Cooling rate KW - High strength steel KW - Microalloy elements KW - HAZ toughness KW - Microstructure PY - 2016 AN - OPUS4-39458 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - NbC grain growth control and mechanical properties of Ni bonded NbC cermets prepared by vacuum liquid phase sintering N2 - The current study reports on the effect of the sintering temperature and secondary carbide (VC, Mo2C and TiC) additions on the microstructure and concommitant Vickers hardness (HV30) and fracture toughness of Ni-bonded NbC cermets. All cermets were prepared by pressureless sintering in vacuum. Detailed microstructural investigation was performed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) analysis. Sintering results indicated that both the sintering temperature and secondary carbide additions had a significant effect on the properties of NbC-Ni cermets. Nickel pools and residual pores were observed in the cermets sintered at temperatures ≤ 1340 °C. Increasing of the sintering temperature up to 1420 or 1480 °C resulted in fully densified NbC-Ni based cermets composed of homogeneous contrast cubic NbC grains for the single carbide (VC or Mo2C) modyfied system, whereas core-rim structured NbC grains were observed with the additon of TiC + VC or TiC+Mo2C. The secondary carbide doped cermets with 5–10 vol.% VC/Mo2C and 10 vol.% TiC showed a significantly improved hardness and fracture toughness, as compared to the plain NbC-Ni cermets. T2 - 19. Plansee Seminar CY - Reutte, Austria DA - 29.05.2017 KW - Cermet KW - Hard materials KW - Sintering KW - Microstructure KW - Core-rim KW - Mechanical properties PY - 2017 SP - HM 13/1 EP - HM 13/11 AN - OPUS4-40592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - Effect of carbon content on the microstructure and mechanical properties of NbC-Ni based cermets N2 - The aim of this work was to correlate the carbon content in NbC-Ni starting powders with the resulting microstructure, hardness and fracture toughness of Ni-bonded NbC cermets. T2 - 19. Plansee Seminar CY - Reutte, Austria DA - 29.05.2017 KW - Cermet KW - Liquid phase sintering KW - Microstructure KW - Hardness KW - Carbon PY - 2017 SP - HM 109/1 EP - HM 109/11 AN - OPUS4-40595 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Haung, S. T1 - NbC grain growth control and mechanical properties of Ni bonded NbC cermets prepared by vacuum liquid phase sintering N2 - The current study reports on the effect of the sintering temperature and secondary carbide (VC, Mo2C and TiC) additions on the microstructure and concommitant Vickers hardness (HV30) and fracture toughness of Ni-bonded NbC cermets. T2 - 19. Plansee Seminar CY - Reutte, Austria DA - 29.05.2017 KW - Cermet KW - Hard materials KW - Sintering KW - Microstructure KW - Core-rim KW - Mechanical properties PY - 2017 AN - OPUS4-40658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huang, S. G. T1 - Effect of carbon content on the microstructure and mechanical properties of NbC-Ni based cermets N2 - The aim of this work was to correlate the carbon content in NbC-Ni starting powders with the resulting microstructure, hardness and fracture toughness of Ni-bonded NbC cermets. T2 - 19. Plansee Seminar CY - Reutte, Austria DA - 29.05.2017 KW - Cermet KW - Liquid phase sintering KW - Microstructure KW - Hardness KW - Carbon PY - 2017 AN - OPUS4-40647 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kempf, A. A1 - Hilgenberg, Kai T1 - Influence of sub-cell structure on the mechanical properties of AlSi10Mg manufactured by laser powder bed fusion N2 - AlSi10Mg is one of the most applied alloys for laser powder bed fusion (LPBF) technology, due to its great possibilities for implementing new lightweight concepts such as in automotive industries. For the component design it is necessary to know about the mechanical properties and the mechanical behaviour. The many published strength properties of LPBF processed AlSi10Mg show significant differences up to approximately 225 MPa in ultimate tensile strength (UTS) and 195 MPa in yield strength (YS). To understand these varying properties, a ring trial was carried out manufacturing specimens on 6 LPBF machines with different parameters and build-up strategies. They were studied in the as-built (AB) condition and after heat treatment at 300 °C for 30 min, respectively. For examining the mechanical properties, tensile tests and hardness measurements were carried out. The microstructure was characterized by optical light microscopy (OM), field emission scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The identified differences in strength properties were discussed based on the 4 strengthening mechanism known for metallic materials and at the background of material defects. It was found that the size of the typical sub-cell structure of LPBF AlSi10Mg affected substantially the mechanical properties in the AB condition, in which with decreasing sub-cell size strength increased. If heat treatment was applied, the strength properties decreased and did not differ anymore. Since annealing led to coarsened sub-cells, whereas the grains itself did not change in size, the influence of sub-cell structure on strength was further confirmed. In addition, acicular precipitates in the AB condition were observed at specimens from one LPBF machine showing the lowest tensile elongation. KW - Laser powder bed fusion KW - AlSi10Mg KW - Mechanical properties KW - Microstructure PY - 2020 DO - https://doi.org/10.1016/j.msea.2020.138976 VL - 776 SP - Paper 138976, 12 PB - Elsevier B.V. AN - OPUS4-50316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sonego, M. A1 - Madia, Mauro A1 - Eder, M. A1 - Fleck, C. A1 - Pessan, L. A. T1 - Microstructural features influencing the mechanical performance of the Brazil nut (Bertholletia excelsa) mesocarp N2 - Brazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests. Fractured specimens were analyzed through scanning electron microscopy (SEM) and microtomography (microCT). Mesocarp showed high deformability (strain at max. stress of ~30%) under compression loading, a critical tensile strength of ~24.9 MPa, a Weibull modulus of ~3, and an elastic modulus of ~2 GPa in the tensile test. The fracture toughness, estimated through the work of fracture of SENB tests, reached ~2 kJ/m2. The thick and strong walls of mesocarp cells, with a weaker boundary between them (compound middle lamella), promote a tortuous intercellular crack path. Several toughening mechanisms, such as crack deflection, breaking of fiber bundles, fiber pullout and bridging as well as crack branching, occur depending on how fiber bundles and voids are oriented. KW - Toughening mechanisms KW - Brazil nut Mesocarp KW - Microstructure KW - Mechanical properties PY - 2021 DO - https://doi.org/10.1016/j.jmbbm.2020.104306 VL - 116 SP - 104306 PB - Elsevier Ltd. AN - OPUS4-52081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -