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 - Cios, G. A1 - Winkelmann, A. A1 - Nolze, Gert A1 - Tokarski, T. A1 - Jany, B. R. A1 - Bala, P. T1 - EBSD and TKD analyses using inverted contrast Kikuchi diffraction patterns and alternative measurement geometries N2 - Electron backscatter diffraction (EBSD) patterns can exhibit Kikuchi bands with inverted contrast due to anomalous absorption. This can be observed, for example, on samples with nanoscale topography, in case of a low tilt backscattering geometry, or for transmission Kikuchi diffraction (TKD) on thicker samples. Three examples are discussed where contrast-inverted physics-based simulated master patterns have been applied to find the correct crystal orientation. As first EBSD example, self-assembled gold nanostructures made of Au fcc and Au hcp phases on single-crystal germanium were investigated. Gold covered about 12% of the mapped area, with only two thirds being successfully interpreted using standard Hough-based indexing. The remaining third was solved by brute force indexing using a contrast-inverted master pattern. The second EBSD example deals with maps collected at a non-tilted surface instead of the commonly used 70◦ tilted one. As TKD example, a jet-polished foil made of duplex stainless steel 2205 was examined. The thin part close to the hole edge producing normal-contrast patterns were standard indexed. The areas of the foil that become thicker with increasing distance from the edge of the hole produce contrast-inverted patterns. They covered three times the evaluable area and were successfully processed using the contrast-inverted master pattern. In the last example, inverted patterns collected at a non-tiled sample were mathematically inverted to normal contrast, and Hough/Radon-based indexing was successfully applied. KW - EBSD KW - TKD KW - Contrast inversion KW - Topography KW - Kikuchi diffraction PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613862 VL - 267 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-61386 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 - Stephan-Scherb, Christiane A1 - Menneken, Martina A1 - Weber, Kathrin A1 - Agudo Jácome, Leonardo A1 - Nolze, Gert T1 - Elucidation of orientation relations between Fe-Cr alloys and corrosionproducts after high temperature SO2 corrosion N2 - The early stages of corrosion of Fe-Cr-model alloys (2 and 9 % Cr) were investigated after exposure at 650 °C in0.5 % SO2containing gas by electron backscattered diffraction (EBSD) and transmission electron microscopy(TEM). The impact of the grain orientation of the base alloy on the orientation relations of the corrosion productsis presented. After 2 min–5 min exposure the formation of a multi-layered corrosion zone was discovered. Aclear orientation relationship between ferrite and the (Fe,Cr)3O4 spinel could be demonstrated. The obtainedresults show the importance of the grain orientation on oxidation resistance. KW - Iron KW - TEM KW - SEM KW - High temperature corrosion PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508911 DO - https://doi.org/10.1016/j.corsci.2020.108809 VL - 174 SP - 1 EP - 11 PB - Elsevier AN - OPUS4-50891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Nolze, Gert A1 - Malakhov, A. Yu. A1 - Pervukhina, O. L. T1 - Investigation of the Structure of Interfaces Between Metals and Alloys Joined by Explosion Welding N2 - The structure of interfaces in Fe20Cr6Al/Cu, titanium/steel and brass/Invar bimetals obtained by explosion welding from sheet components with a thickness of 1 and 4, 25 and 5, 12 and 8 mm, respectively, was studied using analytical methods of scanning electron microscopy. The wave dimensions (length/height) were approximately 200/50 μm for Fe20Cr6Al/Cu, 700/70 μm for titanium/steel and 350/100 μm for brass/Invar. At the micron scale, mutual penetration of the welded components into each other (trans-interface diffusion) was not detected. In the iron-based plate of Fe20Cr6Al/Cu bimetal, a strong texture and cracks, which are a critical defect, were formed as a result of severe plastic deformation. Less pronounced textures were revealed in the components of titanium/steel bimetal. In titanium/steel bimetal, Laves phase particles Fe2Ti were found near the welded interface, while in brass/Invar bimetal, local contact melting was observed. However, the particles Fe2Ti and local melting areas are not critical defects, as they do not cause unacceptable deterioration in the adhesive strength of the welded joints, which was confirmed by a high shear strength of 500-570 MPa for the brass/Invar bimetal. KW - EBSD KW - Welding KW - Interface PY - 2025 DO - https://doi.org/10.1007/s11665-025-12660-x SN - 1059-9495 SP - 1 EP - 11 PB - Springer Science and Business Media LLC AN - OPUS4-64732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Singh, Shobhit Pratap A1 - Löwe, Peter A1 - Schriever, Sina A1 - Olbricht, Jürgen A1 - Rehmer, Birgit A1 - Nolze, Gert A1 - Skrotzki, Birgit T1 - High-throughput creep evaluation of IN738LC in bending using digital image correlation at 850 °C N2 - High-temperature alloys, when used in structural applications, undergo slow time-dependent deformation known as creep. Assessing creep behavior is critical for estimating the in-service life of these alloys. Conventionally, uniaxial creep tests are widely conducted at elevated temperatures to determine creep rates. In recent years, bending creep of cantilevers, when combined with digital image correlation (DIC), has emerged as a promising high-throughput technique for rapidly estimating creep life. However, the applicability of bending creep above 700 ◦C for high-temperature alloys using DIC has not been fully established. In this work, we compare uniaxial creep rates of the nickel-based superalloy IN738LC with bending creep rates measured at 850 ◦C using high-temperature DIC. The bending creep data show excellent agreement with uniaxial creep results in the stress range of 240–360 MPa. The measured creep xponent, a critical rate-determining parameter, is found to be ~8 for both uniaxial and bending creep, with the rate data scattered within a factor of two. An in-house experimental setup was developed to perform bending creep tests at high temperatures, with strain monitored through DIC. Our results demonstrate that bending creep, combined with DIC, provides a reliable and efficient method for creep testing of high-temperature alloys. Compared to conventional uniaxial creep experiments, this approach requires significantly less time and material, thereby reducing effort, energy, and cost. We anticipate that this technique will serve as a foundation for testing precious high-temperature materials. For instance, in ongoing rapid discoveries of advanced alloys, in-service creep life can be evaluated much faster with reduced material requirements. Moreover, this method holds strong potential for application to high-entropy alloys and additively manufactured alloys designed for demanding high-temperature environments. KW - Digital image correlation KW - Bending creep KW - Nickel-based superalloys KW - High throughput testing KW - High-temperature materials PY - 2025 UR - https://www.sciencedirect.com/science/article/pii/S0921509325017034?via%3Dihub DO - https://doi.org/10.1016/j.msea.2025.149479 VL - 950 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-64814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Mishurova, Tatiana A1 - Thiede, Tobias A1 - Sprengel, Maximilian A1 - Kromm, Arne A1 - Nadammal, Naresh A1 - Nolze, Gert A1 - Saliwan Neumann, Romeo A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - The residual stress in as‑built Laser Powder Bed Fusion IN718 alloy as a consequence of the scanning strategy induced microstructure N2 - The effect of two types of scanning strategies on the grain structure and build-up of Residual Stress (RS) has been investigated in an as-built IN718 alloy produced by Laser Powder Bed Fusion (LPBF). The RS state has been investigated by X-ray diffraction techniques. The microstructural characterization was performed principally by Electron Backscatter Diffraction (EBSD), where the application of a post-measurement refinement technique enables small misorientations (< 2°) to be resolved. Kernel average misorientation (KAM) distributions indicate that preferably oriented columnar grains contain higher levels of misorientation, when compared to elongated grains with lower texture. The KAM distributions combined with X-ray diffraction stress maps infer that the increased misorientation is induced via plastic deformation driven by the thermal stresses, acting to self-relieve stress. The possibility of obtaining lower RS states in the build direction as a consequence of the influence of the microstructure should be considered when envisaging scanning strategies aimed at the mitigation of RS. KW - Additive manufacturing KW - LPBF KW - Residual stress KW - Inconel 718 KW - Kernel average misorientation KW - Texture PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511769 DO - https://doi.org/10.1038/s41598-020-71112-9 VL - 10 IS - 1 SP - 14645 AN - OPUS4-51176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Fedelich, Bernard A1 - Finn, Monika A1 - Künecke, Georgia A1 - Rehmer, Birgit A1 - Nolze, Gert A1 - Leistner, C. A1 - Petrushin, N. A1 - Svetlov, I. T1 - Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C N2 - The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as during technical accidents which may happen in service (overheating). High reliability of the results was achieved using specimens of different crystallographic orientations, exciting various vibration modes as well as precise measurement of the material density and thermal Expansion required for modeling the resonance frequencies by finite element method. Combining the results measured in this work and literature data the elastic constants of the gamma and gamma' phases were predicted. This prediction was supported by measurement of the temperature dependence of the gamma'fraction. All data obtained in this work are given in numerical or analytical forms and can be easily used for different scientific and engineering calculations. KW - Nickel-base superalloys KW - Single-crystals KW - Characterization KW - Elastic constants PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520972 DO - https://doi.org/10.3390/cryst11020152 VL - 11 IS - 2 SP - 152 PB - MDPI AN - OPUS4-52097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -