Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-55163 Zeitschriftenartikel Svetlov, I. L.; Epishin, A. I.; Petrushin, N. V.; Gerstein, G.; Nolze, Gert; Maier, H. J. Creep of Directionally Solidified Eutectics Ni/Ni3 Al-NbC under Thermal Cycling 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. Dordrecht Springer Science + Business Media 2022 Inorganic Materials: Applied research 13 4 1099 1108 10.1134/S2075113322040347 2022-07-04 OPUS4-56409 Zeitschriftenartikel Epishin, A.I.; Nolze, Gert; Alymov, M.I. Pore Morphology in Single Crystals of a Nickel-Based Superalloy After Hot Isostatic Pressing 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. Springer Nature 2022 Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science 1 9 10.1007/s11661-022-06893-x 2022-11-28 OPUS4-56596 Zeitschriftenartikel Malakhov, A.; Epishin, A.; Denisov, I.; Saikov, I.; Nolze, Gert Morphology and Structure of Brass-Invar Weld Interface after Explosive Welding 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. MDPI 2022 Materials 15 23 1 10 urn:nbn:de:kobv:b43-565964 10.3390/ma15238587 https://creativecommons.org/licenses/by/4.0/deed.de 2022-12-19 OPUS4-54466 Zeitschriftenartikel Treninkov, I. A.; Petrushin, N. V.; Epishin, A. I.; Svetlov, I. L.; Nolze, Gert; Elyutin, E. S. Experimental Determination of Temperature Dependence of Structural-Phase Parameters of Nickel-Based Superalloy 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. Dordrecht Springer Science + Business Media 2022 Inorganic Materials: Applied Research 13 1 171 178 10.1134/s2075113322010373 2022-03-14 OPUS4-54275 Zeitschriftenartikel Schneider, J.; Farris, L.; Nolze, Gert; Reinsch, Stefan; Cios, G.; Tokarski, T.; Thompson, S. Microstructure evolution in Inconel 718 produced by powder bed fusion additive manufacturing 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. Basel MDPI 2022 Journal of manufacturing and materials processing 6 1 1 20 urn:nbn:de:kobv:b43-542758 10.3390/jmmp6010020 https://creativecommons.org/licenses/by/4.0/deed.de 2022-02-03 OPUS4-54379 Zeitschriftenartikel Epishin, A. I.; Petrushin, N. V.; Svetlov, I. L.; Nolze, Gert Model for Forecasting Temperature Dependence of γ/γ' Misfit in Heat-Resistant Nickel Alloys 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. Springer 2022 Inorganic Materials: Applied Research 13 1 7 16 10.1134/S2075113322010105 2022-02-21 OPUS4-52097 Zeitschriftenartikel Epishin, A.; Fedelich, Bernard; Finn, Monika; Künecke, Georgia; Rehmer, Birgit; Nolze, Gert; Leistner, C.; Petrushin, N.; Svetlov, I. Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C 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. MDPI 2021 Crystals 11 2 152 urn:nbn:de:kobv:b43-520972 10.3390/cryst11020152 https://creativecommons.org/licenses/by/4.0/deed.de 2021-02-10 OPUS4-52147 Zeitschriftenartikel Epishin, A.; Camin, B.; Hansen, L.; Chyrkin, A.; Nolze, Gert Synchrotron Sub-μ X-ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel-Base Superalloy and Nickel after Annealing at 1250 °C 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. Wiley Online Library 2021 Advanced Engineering Materials 23 4 1220 urn:nbn:de:kobv:b43-521476 10.1002/adem.202001220 https://creativecommons.org/licenses/by/4.0/deed.de 2021-02-22 OPUS4-53109 Zeitschriftenartikel Winkelmann, A.; Nolze, Gert; Cios, G.; Tokarski, T.; Bala, P.; Hourahine, B.; Trager-Cowan, C. Kikuchi pattern simulations of backscattered and transmitted electrons We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness- and energy-dependent features which are observed in experimental Kikuchi diffraction patterns. Excess-deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two-beam approximation to dynamical electron diffraction, a phenomenological model of excess-deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre-calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKDcan be affected by changes in the order of 10−3-10-2 if excess-deficiency features are not considered in the theoreticalmodel underlying a best-fit pattern matching approach. Correspondingly, the absolute accuracy of simulation-based EBSD strain determination can suffer frombiases of a similar order of magnitude if excess-deficiency effects are neglected in the simulation model. Wiley Online Library 2021 Journal of Microscopy 284 2 157 184 10.1111/jmi.13051 2021-08-18 OPUS4-53110 Zeitschriftenartikel Treninkov, И. A; Petrushin, N. V.; Epishin, А. I.; Svetlov, I. L.; Nolze, Gert; Elyutin, E. S. ЭКСПЕРИМЕНТАЛЬНОЕ ОПРЕДЕЛЕНИЕ ТЕМПЕРАТУРНОЙ ЗАВИСИМОСТИ СТРУКТУРНО-ФАЗОВЫХ ПАРАМЕТРОВ НИКЕЛЕВОГО ЖАРОПРОЧНОГО СПЛАВА 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. 2021 ФИЗИЧЕСКИЕ ОСНОВЫ МАТЕРИАЛОВЕДЕНИЯ 7 3 12 10.31044/1684-579x-2021-0-7-3-12 2021-08-18 OPUS4-53174 Zeitschriftenartikel Tokarski, T.; Nolze, Gert; Winkelmann, A.; Rychlowski, L.; Bala, P.; Cios, G. Transmission Kikuchi diffraction: The impact of the signal-to-noise ratio 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. Amsterdam Elsevier 2021 Ultramicroscopy 230 1 8 urn:nbn:de:kobv:b43-531743 10.1016/j.ultramic.2021.113372 https://creativecommons.org/licenses/by/4.0/deed.de 2021-09-02 OPUS4-52707 Zeitschriftenartikel Nolze, Gert; Tokarski, T.; Rychlowski, L.; Cios, G.; Winkelmann, A. Crystallographic analysis of the lattice metric (CALM) from single electron backscatter diffraction or transmission Kikuchi diffraction patterns A new software is presented for the determination of crystal lattice parameters from the positions and widths of Kikuchi bands in a diffraction pattern. Starting with a single wide-angle Kikuchi pattern of arbitrary resolution and unknown phase, the traces of all visibly diffracting lattice planes are manually derived from four initial Kikuchi band traces via an intuitive graphical user interface. A single Kikuchi bandwidth is then used as reference to scale all reciprocal lattice point distances. Kikuchi band detection, via a filtered Funk transformation, and simultaneous display of the band intensity profile helps users to select band positions and widths. Bandwidths are calculated using the first derivative of the band profiles as excess-deficiency effects have minimal influence. From the reciprocal lattice, the metrics of possible Bravais lattice types are derived for all crystal systems. The measured lattice parameters achieve a precision of <1%, even for good quality Kikuchi diffraction patterns of 400 x 300 pixels. This band-edge detection approach has been validated on several hundred experimental diffraction patterns from phases of different symmetries and random orientations. It produces a systematic lattice parameter offset of up to ±4%, which appears to scale with the mean atomic number or the backscatter coefficient. 2021 Journal of Applied Crystallography 54 Pt 3 1012 1022 urn:nbn:de:kobv:b43-527076 10.1107/S1600576721004210 https://creativecommons.org/licenses/by/4.0/deed.de 2021-05-31 OPUS4-44805 Zeitschriftenartikel Reith, F.; Rea, M.A.D.; Sawley, P.; Zammit, C.M.; Nolze, Gert; Reith, T.; Rantanen, K.; Bissett, A. Biogeochemical cycling of gold: Transforming gold particles from arctic Finland (Bio)geochemical cycling of gold (Au) has been demonstrated in present-day (semi)-arid, (sub)-tropical and temperate environment. Hereby biofilms on Au-bearing mineral- and Au-particle surfaces drive Au dispersion and reconcentration, thereby (trans)forming the particles. However, it is unknown if biogeochemical cycling of Au occurs in polar environments, where air temperatures can reach −40 °C and soils remain frozen for much of the year. Therefore, placer Au-particles, soils and waters were collected at two placer mining districts in arctic Finland, i.e., the Ivalojoki and Lemmenjoki goldfields. Sites were chosen based on contrasting settings ((glacio)-fluvial vs. glacial-till deposits) and depths (surface to 5m below current surface). Gold particles were studied using a combination of tagged 16S rRNA gene next generation sequencing and electron microscopic/microanalytical techniques. Across all sites a range of Au-particle morphologies were observed, including morphotypes indicative of Au dissolution and aggregation. Elevated Au concentrations indicative of Au mobility were detected in placer particle bearing soils at both districts. Typically Au-particles were coated by polymorphic biofilm layers composed of living and dead cells embedded in extracellular polymeric substances. Intermixed were biominerals, clays and iron-sulfides/oxides and abundant secondary Au morphotypes, i.e., nano-particles, microcrystals, sheet-like Au, branched Au networks and overgrowths and secondary rims. Biofilms communities were composed of Acidobacteria (18.3%), Bacteroidetes (15.1%) and Proteobacteria (47.1%), with β-Proteobacteria (19.5%) being the most abundant proteobacterial group. Functionally, biofilms were composed of taxa contributing to biofilm establishment, exopolymer production and nutrient cycling, abundant taxa capable of Au mobilization, detoxification and biomineralization, among them Cupriavidus metallidurans, Acinetobacter spp. and Pseudomonas spp., were detected. In conclusion, these results demonstrate that placer Au-particle transformation and Au dispersion occur in cold, arctic environments. This corroborates the existence of biogeochemical Au cycling in present-day cold environments. Elsevier 2018 Chemical Geology 483 511 529 10.1016/j.chemgeo.2018.03.021 2018-05-02 OPUS4-45395 Zeitschriftenartikel Epishin, A.; Petrushin, N.; Gerstein, G.; Maier, J.; Nolze, Gert Investigation of the gamma'-strengthened quaternary co-based alloys Co-Al-W-Ta The alloying system Co-Al-W-Ta is comprehensively investigated in the vicinity of the compositional point Co-9Al-10W-2Ta, at. pct. These investigations provided a large amount of quantitative information, which can be used for alloy development, namely, the compositional dependences of the The alloying system Co-Al-W-Ta is comprehensively investigated in the vicinity of the compositional point Co-9Al-10W-2Ta, at. pct. These investigations provided a large amount of quantitative information, which can be used for alloy development, namely, the compositional dependences of the γ'-solvus, solidus, and liquidus temperatures; fraction of the extrinsic phases after casting; the compositional dependence of the γ/γ'-lattice misfit; the element partitioning between γ- and γ'-phases; and the two Phase compositional area γ/γ' in the Co-rich part of the Co-Al-W-Ta phase diagram at 900°C. It is shown that additions of Ta elevate the γ'-solvus temperature and increase the γ/γ'-lattice misfit, but adding more than about 3 at. pct Ta results in a large amount of undissolvable extrinsic phases. Additionally, two Co-Al-W-Ta alloys with lower content of W were developed and solidified as [001] single crystals for mechanical testing in a temperature range between 20 and 1200°C. These tests included measurement of the Young modulus, tensile tests with constant strain rate, and stress rupture tests. It was found that at temperatures up to about 750°C the ultimate tensile strength of Co-Al-Ta-W alloys can be at the same level or even higher than of Ni-based superalloys. New York, NY Springer Sciences & Business Media The Minerals, Metals and Materials Society (TMS) 2018 Metallurgical and materials transactions A 49A 9 4042 4057 10.1007/s11661-018-4756-3 2018-07-06 OPUS4-44463 Zeitschriftenartikel Epishin, A.; Chyrkin, A.; Nolze, Gert; Midtlyng, Jan; Mayer, H. M.; Petrushin, N.; Reimers, W. Interdiffusion in the Face-Centered Cubic Phase of the Co-Al-W-Ta System Between 1090 and 1240 °C Interdiffusion of Al, W, Ta and Co in a Co-base alloy at temperatures between 1090 and 1240 °C has been investigated. The interdiffusion coefficients were found to be close to those reported for these elements in Ni-base alloys. Combining the diffusion simulation software DICTRA with the Ni-base diffusion databases TCNi5 and MobNi3, the interdiffusion profiles of Co, Al W, and Ta were modeled for Co9Al8W2Ta/Co diffusion couples annealed at different temperatures and for different times. The results show that interdiffusion in the Co-Al-W-Ta alloys can be modeled reasonably well using the available commercial databases for thermodynamics and kinetics of Ni-base systems. Springer 2018 Journal of Phase Equilibria and Diffusion 39 2 176 185 10.1007/s11669-018-0620-9 2018-03-14 OPUS4-44840 Beitrag zu einem Tagungsband Röhsler, Andreas; Sobol, Oded; Nolze, Gert; Unger, Wolfgang; Böllinghaus, Thomas Use of time-of-flight secondary ion mass spectrometry for the investigation of hydrogen-induced effects in austenitic steel AISI 304L During the energy transformation from fossil fuels to renewable energy sources, the use of hydrogen as fuel and energy storage can play a key role. This presents new challenges to industry and the scientific community alike. The storage and transport of hydrogen, which is nowadays mainly realized by austenitic stainless steels, remains problematic, which is due to the degradation of mechanical properties and the possibility of phase transformation by hydrogen diffusion and accumulation. The development of materials and technologies requires a fundamental understanding of these degradation processes. Therefore, studying the behavior of hydrogen in austenitic steel contributes to an understanding of the damage processes, which is crucial for both life assessment and safe use of components in industry and transportation. As one of the few tools that is capable of depicting the distribution of hydrogen in steels, time-of-flight secondary ion mass spectrometry was conducted after electrochemical charging. To obtain further information about the structural composition and cracking behavior, electron-backscattered diffraction and scanning electron microscopy were performed. Gathered data of chemical composition and topography were treated employing data fusion, thus creating a comprehensive portrait of hydrogen-induced effects in the austenite grade AISI 304L. Specimens were electrochemically charged with deuterium instead of hydrogen. This arises from the difficulties to distinguish between artificially charged hydrogen and traces existing in the material or the rest gas in the analysis chamber. Similar diffusion and permeation behavior, as well as solubility, allow nonetheless to draw conclusions from the experiments. American Vacuum Society (AVS) 2018 Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 36 21st International Conference on Secondary Ion Mass Spectrometry Kraków, Poland 10.09.2017 3 Article 03F103, 1 6 10.1116/1.5013931 2018-05-07 OPUS4-45165 Zeitschriftenartikel Böllinghaus, Thomas; Lüders, V.; Nolze, Gert Microstructural insights into natural silver wires Due to the increasing global demand for pure silver, native wire silver aggregates in very high purities are gaining more industrial attention. Up to the present, no substantial metallurgical Investigation of natural wire silver exists in the accessible literature. To convey urgently needed cross-disciplinary fundamental knowledge for geoscientists and metallurgical engineers, twenty natural wire silver specimens from eight different ore deposits have been investigated in detail for the first time by EBSD (Electron Back Scattering Diffraction), supported by light microscopy and micro-probe analyses. The improved understanding of the natural silver wire microstructure provides additional Information regarding the growth of natural silver aggregates in comparison to undesired artificial growth on electronic devices. Clear evidence is provided that natural silver curls and hairs exhibit a polycrystalline face-centered cubic microstructure associated with significant twinning. Although the investigated natural wire silver samples have relatively high purity (Ag > 99.7 wt.-%), they contain a variety of trace elements such as, S, Cu, Mn, Ni, Zn, Co and Bi, As and Sb. Additionally, Vickers micro-hardness measurements are provided for the first time which revealed that natural silver wires and curls are softer than it might be expected from conversion of the general Mohs hardness of 2.7. London, United Kingdom nature publishing group 2018 Nature - Scientific Reports 8 1 Article 9053, 1 9 urn:nbn:de:kobv:b43-451655 10.1038/s41598-018-27159-w https://creativecommons.org/licenses/by/4.0/deed.de 2018-06-13 OPUS4-50934 Zeitschriftenartikel Winkelmann, A.; Nolze, Gert; Cios, G.; Tokarski, T.; Bala, P. Refined Calibration Model for Improving the Orientation Precision of Electron Backscatter Diffraction Maps For the precise determination of orientations in polycrystalline materials, electron backscatter diffraction (EBSD) requires a consistent calibration of the diffraction geometry in the scanning electron microscope (SEM). In the present paper, the variation of the projection center for the Kikuchi diffraction patterns which are measured by EBSD is calibrated using a projective transformation model for the SEM beam scan positions on the sample. Based on a full pattern matching approach between simulated and experimental Kikuchi patterns, individual projection center estimates are determined on a subgrid of the EBSD map, from which least-square fits to affine and projective transformations can be obtained. Reference measurements on single-crystalline silicon are used to quantify the orientation errors which result from different calibration models for the variation of the projection center. MDPI 2020 Materials 13 12 2816 urn:nbn:de:kobv:b43-509342 10.3390/ma13122816 https://creativecommons.org/licenses/by/4.0/deed.de 2020-06-24 OPUS4-51176 Zeitschriftenartikel Serrano Munoz, Itziar; Mishurova, Tatiana; Thiede, Tobias; Sprengel, Maximilian; Kromm, Arne; Nadammal, Naresh; Nolze, Gert; Saliwan Neumann, Romeo; Evans, Alexander; Bruno, Giovanni The residual stress in as‑built Laser Powder Bed Fusion IN718 alloy as a consequence of the scanning strategy induced microstructure 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. 2020 Scientific reports 10 1 14645 urn:nbn:de:kobv:b43-511769 10.1038/s41598-020-71112-9 https://creativecommons.org/licenses/by/4.0/deed.de 2020-09-09 OPUS4-50891 Zeitschriftenartikel Stephan-Scherb, Christiane; Menneken, Martina; Weber, Kathrin; Agudo Jácome, Leonardo; Nolze, Gert Elucidation of orientation relations between Fe-Cr alloys and corrosionproducts after high temperature SO2 corrosion 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. Elsevier 2020 Corrosion Science 174 1 11 urn:nbn:de:kobv:b43-508911 10.1016/j.corsci.2020.108809 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2020-06-18