TY - CONF A1 - Abram, Sarah-Luise A1 - Mrkwitschka, Paul A1 - Prinz, Carsten A1 - Rühle, Bastian A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan A1 - Resch-Genger, Ute T1 - Monodisperse iron oxide nanoparticles as reference material candidate for particle size measurements N2 - In order to utilize and rationally design materials at the nanoscale the reliable characterization of their physico-chemical properties is highly important, especially with respect to the assessment of their environmental or biological impact. Furthermore, the European Commission’s REACH Regulations require the registration of nanomaterials traded in quantities of at least 1 ton. Powders or dispersions where 50% (number distribution) of the constituent particles have sizes ≤ 100 nm in at least one dimension are defined as nanomaterials. This creates a need for industrial manufacturers and research or analytical service facilities to reliably characterize potential nanomaterials. Currently, BAM is developing reference nanoparticles, which shall expand the scarce list of worldwide available nano reference materials certified for particle size distribution and will also target other key parameters like shape, structure, porosity or functional properties. In this respect, materials like iron oxide or titanium dioxide are considered as candidates to complement the already available silica, Au, Ag, and polystyrene reference nanoparticles. The thermal decomposition of iron oleate precursors in high boiling organic solvents can provide large quantities of iron oxide nanoparticles that can be varied in size and shape.[1, 2] The presence of oleic acid or other hydrophobic ligands as capping agents ensures stable dispersion in nonpolar solvents. Such monodisperse, spherical particles were synthesized at BAM and pre-characterized by electron microscopy (TEM, SEM including the transmission mode STEM-in-SEM) and dynamic light scattering comparing cumulants analysis and frequency power spectrum. 1. REACH regulations and nanosafety concerns create a strong need for nano reference materials with diverse properties. 2. Iron oxide nanoparticles are under development as new candidate reference material at BAM. 3. Narrow particle size distribution confirmed by light scattering and electron microscopy. T2 - Nanosafety 2020 CY - Online meeting DA - 05.10.2020 KW - Iron oxide nanoparticles KW - Reference material KW - Particle size KW - Electron microscopy KW - Nanoplattform PY - 2020 AN - OPUS4-52774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Sobek, P. A1 - Körner, S. A1 - Müller, Ralf T1 - Silver - alkali borate glass pastes N2 - Network modifier ions can decisively influence properties and structure of low melting alkali-zinc-borate glasses and thus cause complex effects on the liquid phase sintering of silver-glass metallization pastes. This effect was studied for X2O-ZnO-B2O3 (X = Li, Na, Rb) glasses for silver-glass metallization pastes. Viscosity and the glass transition temperature, Tg, were measured with rotational viscometry and dilatometry. Dried model pastes with 30 vol% LZB, NZB or RZB glass were prepared for sintering studies by means of heating microscopy measuring the silhouette area shrinkage of uniaxially pressed powder compacts during heating at 5 K/min. For comparison, the silhouette area shrinkage of pure glass and silver powder compacts were determined. Glass-silver wetting was investigated during heating of bulk glass cylinders placed on silver substrates. Glass RZB turned out to have the lowest viscosity among the glasses under study. Its glass transformation temperature, Tg, was found at 444 °C and it caused the lowest sintering onset for its glass and paste powder compacts. Slightly increased values of Tg were found for NZB and LZB (468 °C and 466 °C, respectively) and a slightly retarded sintering was found for both paste powder compacts. These results indicate that liquid phase sintering of silver-glass pastes under air atmosphere is mainly influenced by glass viscosity. T2 - GLASS MEETING 2020 CY - Online meeting DA - 07.12.2020 KW - Silver-glass metallization paste KW - Sintering KW - Alkali ions KW - Viscosity KW - Silver precipitates PY - 2020 AN - OPUS4-52871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Manzoni, Anna Maria T1 - Welding of high-entropy alloys - New material concept vs. old challenges N2 - HEAs represent a relatively new class of materials. The the alloy concept is fundamentally different from the most conventional materials and alloys that are used today. Recently, the focus of HEA designs is more application-based. For that purpose, the elements of interest are carefully selected and multiple phases as well as micro-structures are deliberately adjusted. Currently, only limited attention has been paid to weldability of HEA. This encompasses possible effects on metallurgy and its influence on the desired properties. It remains open if welding causes e.g. considerable number of intermetallic phases or segregations and their effect on weld joint properties. For that reason, the scope of this study is to summarize already available studies on welding of HEAs with respect to the HEA-type, the applied welding process and its influence on the weld joint properties. T2 - IIW Annual Assembly, Meeting of Commission II-A CY - Online meeting DA - 20.07.2020 KW - High-entropy alloy KW - Welding KW - Review PY - 2020 AN - OPUS4-51116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Manzoni, Anna Maria A1 - Richter, Tim A1 - Rhode, Michael A1 - Schröpfer, Dirk T1 - Reliable welding of high-entropy alloys N2 - The importance of high-entropy alloy (HEAs) in the field of materials research is increasing continuously and numerous studies have been published, recently. These are mainly focused on manufacturing of different alloy systems having excellent structural properties from low to high temperatures. Therefore, HEAs are of high potential for many applications in very demanding conditions. However, this is so far limited by poor knowledge and experience regarding economic and reliable component manufacturing. The processability of HEAs has hardly been investigated so far, indicated by the small number of publications worldwide: welding <30 and machining <5. Hence, this contribution provides an overview about the current state of the art on processing of HEAs. Fundamental principles are shown for safe weld joints while ensuring high component integrity. For safe welding, the combined consideration of complex interactions of material, construction and process is necessary. Recent studies on different HEAs showed the influence of heat input by means of different welding processes on the microstructure and respective properties. Based on intensive literature survey and on our initial study, the main research objectives of processing HEAs are presented. T2 - ICHEM 2020 - Third International Conference on High Entropy Materials CY - Berlin, Germany DA - 27.09.2020 KW - High Entropy Alloy KW - Welding KW - Welding processing influences PY - 2020 AN - OPUS4-51591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago A1 - Madia, Mauro A1 - Sommer, Konstantin A1 - Sprengel, Maximilian A1 - Zerbst, Uwe T1 - Short fatigue crack propagation in L-PBF 316L stainless steel N2 - Fracture mechanics is a key to fatigue assessment in AM metal components. Short fatigue cracks are initiated at defects and pronounced surface roughness intrinsic to AM. The subsequent crack-propagation is strongly influenced by microstructural interactions and the build-up of crack-closure. The aim of the present study is to give an insight into short-crack propagation in AM-metals. Fatigue crack propagation resistance curves were determined experimentally for AISI 316L manufactured by Laser Powder Bed Fusion (L-PBF) which was heat treated at three different temperatures. Differences in the build-up of the fatigue-crack propagation threshold in between the L-PBF specimens and compared to wrought material are due to the residual stress states, a pronounced roughness of the crack-faces in the L-PBF specimens and phase transformation in the vicinity of the crack-tip, resulting in increased crack-closure. This, together with crack-branching found along the crack path, enhances the resistance to the propagation of fatigue cracks. T2 - ASTM International Conference on Additive Manufacturing 2020 CY - Online meeting DA - 16.11.2020 KW - Additive Manufacturing KW - Cyclic R-Curve KW - Component assessment KW - L-PBF KW - 316L KW - Residual Stress KW - Fatigue Crack Growth PY - 2020 AN - OPUS4-51585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane A1 - Schulz, Wencke A1 - Karafiludis, Stephanos A1 - Schneider, Mike A1 - Laplanche, Guillaume T1 - Effect of a mixed atmosphere H2O-O2-SO2 on the oxidation kinetics and phase formation on CrMnFeCoNi and CrCoNi N2 - The high-entropy alloy (HEA) CrMnFeCoNi and the medium-entropy alloy (MEA) CrCoNi with a face-centered cubic (fcc) structure have excellent mechanical properties and are considered for high-temperature applications. Both materials were exposed under several oxidized atmospheres in a wide temperature range/regime. Mn-oxide (Mn3O4, Mn2O3) was mainly formed on the HEA and Cr2O3 on the MEA. The fast diffusion of manganese prevents the formation of a continuous chromia layer on CrMnFeCoNi in Ar-O2, Ar-H2O and Ar-SO2 at 800°C. The Cantor alloy and his ternary subsystem CrCoNi were exposed in Ar-O2-H2O-SO2 at 800°C up to 96 h to clarify their oxidation behavior in a mixed atmosphere. The oxidized samples were analyzed by weight measurement, scanning electron microscopy (SEM), and X-ray diffraction analysis (XRD). It was found that mass gain of all samples increased with increasing exposure time. The oxidation rate of the Cantor alloy is significantly higher than that of the ternary alloy system. T2 - International Conference on High Entropy Materials CY - Berlin, Germany DA - 27.09.2020 KW - High Entropy Alloys KW - Medium Entropy Alloys KW - High temperature corrosion KW - Oxidation KW - Sulfidation PY - 2020 AN - OPUS4-51488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza T1 - A model for grain boundary thermodynamics N2 - Systematic microstructure design requires reliable thermodynamic descriptions of each and all microstructure elements. While such descriptions are well established for most bulk phases, thermodynamic assessment of microstructure defects is challenging because of their individualistic nature. In this paper, a model is devised for assessing grain boundary thermodynamics based on available bulk thermodynamic data. We propose a continuous relative atomic density field and its spatial gradients to describe the grain boundary region with reference to the homogeneous bulk and derive the grain boundary Gibbs free energy functional. The grain boundary segregation isotherm and phase diagram are computed for a regular binary solid solution, and qualitatively benchmarked for the Pt–Au system. The relationships between the grain boundary's atomic density, excess free volume, and misorientation angle are discussed. Combining the current density-based model with available bulk thermodynamic databases enables constructing databases, phase diagrams, and segregation isotherms for grain boundaries, opening possibilities for studying and designing heterogeneous microstructures. KW - Phase Diagram KW - Thermodynamics KW - Grain boundary PY - 2020 VL - 10 IS - 45 SP - 26728 EP - 26741 AN - OPUS4-51268 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella A1 - Trappe, Volker A1 - Trappe, Volker A1 - Nielow, Dustin T1 - Non-destructive characterization methods for polymer matrix composites N2 - The mechanical behavior of fiber reinforced composites with polymer matrix is governed by several mechanisms operating at different length scales. In this contribution we describe first non-destructive techniques which are adequate for the characterization of the fiber-matrix interphase at a microscopic level. In a second step we describe on a mesoscopic level the influence of manufacturing related elements on the mechanical properties of rotor blades for wind turbines. We concentrate on thermography, laminography and ultrasound in connection with mechanical testing systems. Finally we present methods for monitoring rotor blades by using embedded optical fibers. T2 - Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ, Brasilien CY - Online meeting DA - 26.11.2020 KW - Polymer matrix composites PY - 2020 AN - OPUS4-52043 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila, Luis A1 - Rehmer, Birgit A1 - Graf, B. A1 - Ulbricht, Alexander A1 - Skrotzki, Birgit A1 - Rethmeier, Michael T1 - Assessing the low cycle fatigue behaviour of additively manufactured Ti-6Al-4V: Challenges and first results N2 - The understanding of process-microstructure-property-performance (PMPP) relationships in additive manufacturing (AM) of metals is highly necessary to achieve wide-spread industrial application and replace conventionally manufactured parts, especially regarding safety-relevant applications. To achieve this understanding, reliable data and knowledge regarding material’s microstructure-property relationships (e.g. the role of defects) is needed, since it represents the base for future more targeted process optimizations and more reliable calculations of performance. However, producing reliable material data and assessing the AM material behaviour is not an easy task: big challenges are e.g. the actual lack of standard testing methods for AM materials and the occasional difficulties in finding one-to-one comparable material data for the conventional counterpart. This work aims to contribute to end this lack of reliable material data and knowledge for the low cycle fatigue behaviour of the most used titanium alloy in aerospace applications (Ti-6Al-4V). For this purpose, two sets of test specimens were investigated. The first set was manufactured from cylindrical rods produced by an optimized DED-L process and the second was manufactured from a hot formed round bar. The test specimens were cyclically loaded until failure in the low-cycle-fatigue (LCF) regime. The tests were carried out according to ISO 12106 between 0.3 to 1.0 % axial strain amplitude from room temperature up to 400°C. The LCF behaviour is described and compared between materials and with literature values based on cyclic deformation curves and strain-based fatigue life curves. Besides, the parameters of Manson-Coffin-Basquin relationship were calculated. The microstructures (initial and after failure) and fracture surfaces were comparative characterized. Thereby, the focus lied on understanding the role of grain morphology and defects on the failure mechanisms and fatigue lifetimes. For this latter characterization, optical microscopy (OM), scanning electron microscopy (SEM) and micro computed tomography (µCT) were used. T2 - 4th International Symposium on Fatigue Design and Material Defects CY - Online meeting DA - 26.05.2020 KW - Ti-6Al-4V KW - Additive manufacturing KW - Low cycle fatigue KW - Micro computed tomography KW - Microstructure PY - 2020 AN - OPUS4-50893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Artzt, Katia A1 - Haubrich, Jan A1 - Requena, Guillermo A1 - Bruno, Giovanni A1 - Rehmer, Birgit T1 - Influence of residual stress and microstructure on mechanical performance of LPBF TI-6AL-4V N2 - Ti-6Al-4V alloy is intensively used in the aerospace industry because of its high specific strength. However, the application of Laser Powder Bed Fusion (LPBF) Ti-6Al-4V alloy for structurally critical load-bearing components is limited. One of the main limiting factors affecting the structural integrity, are manufacturing defects. Additionally, the high cooling rates associated with LPBF process result in the formation of large residual stress (RS) with complex fields. Such RS can cause cracking and geometrical distortions of the part even right after production. Also, the microstructure of LPBF Ti-6Al-4V in the as-built condition is significantly different from that of the conventionally produced alloy. All these factors affect the mechanical behavior of the material. Therefore, to improve the material performance it is important to evaluate the individual effect of RS, defects, and microstructure on fatigue life. To this aim Ti-6Al-4V LPBF material in as-built condition and subjected to different post-processing, including two heat treatments (for stress relief and microstructural modification) and Hot Isostatic Pressing (HIP, for densification), were investigated. Prior to Low Cycle Fatigue (LCF) tests at operating temperature (300°C), the microstructure (phases, crystallographic texture, and grain morphology), the mesostructure (defect shape and distribution), and subsurface RS on the LCF samples were investigated. It was found that the fatigue performance of HIPped samples is similar to that of conventionally produced Ti-6Al-4V. The tensile RS found at the surface of as-built samples decreased the fatigue life compared to heat-treated samples. Additionally, the modification of the microstructure (by heat treatment) did not affect the fatigue performance in the regime of mostly elastic strain. This shows that in the absence of tensile RS the manufacturing defects solely control the failure of LPBF components and densification has the strongest effect on the improvement of the mechanical performance. T2 - ASTM ICAM 2020 CY - Online meeting DA - 16.11.2020 KW - Additive manufacturing KW - Ti-6Al-4V KW - Computed tomography KW - Residual stress PY - 2020 AN - OPUS4-51695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Butz, Adam A1 - Fedelich, Bernard A1 - Rehmer, Birgit A1 - Mäde, L. T1 - Detection and prediction of high temperature fatigue crack growth around notches in polycrystalline nickel base alloy N2 - Im Rahmen eines Vorhabens wurden Methoden zur Reduktion des Versuchsaufwandes bei der Modellerstellung für LCF-Lebensdauervorhersage untersucht. Einige dieser Methoden sind hier kurz vorgestellt. N2 - Methods for reducing the experimental effort necessary for the development of LCF life time prediction models were investigated. Some of these methods are briefly presented here. T2 - 4th International Symposium for Fatigue Design and Material Defects CY - Online meeting DA - 26.05.2020 KW - LCF KW - Mechanistic Modelling KW - Fatigue KW - Data Fusion PY - 2020 AN - OPUS4-50904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, L. A1 - Darvishi Kamachali, Reza A1 - Li, Z. A1 - Zhang, Z. T1 - Grain boundary energy effect on grain boundary segregation in an equiatomic high-entropy alloy N2 - Grain boundary (GB) Segregation has a substantial effect on the microstructure evolution and properties of polycrystalline alloys. The mechanism of nanoscale segregation at the various GBs in multicomponent alloys is of great challenge to reveal and remains elusive so far. To address this issue, we studied the GB segregation in a representative equiatomic FeMnNiCoCr high-entropy alloy (HEA) aged at 450 °C. By combining transmission Kikuchi diffraction, atom probe tomography analysis and a density-based thermodynamics modeling, we uncover the nanoscale segregation behavior at a series of well-characterized GBs of different characters. No segregation occurs at coherent twin boundaries; only slight nanoscale segregation of Ni takes place at the low-angle GBs and vicinal \Sigma 29b coincidence site lattice GBs. Ni and Mn show cosegregation of high levels at the general high-angle GBs with a strong depletion in Fe, Cr, and Co. Our density-based thermodynamic model reveals that the highly negative energy of mixing Ni and Mn is the main driving force for nanoscale cosegregation to the GBs. This is further assisted by the opposite segregation of Ni and Cr atoms with a positive enthalpy of mixing. It is also found that GBs of higher interfacial energy, possessing lower atomic densities (higher disorder and free volume), show higher segregation levels. By clarifying the origins of GB segregations in the FeMnNiCoCr HEA, the current work provides fundamental ideas on nanoscale segregation at crystal defects in multicomponent alloys. KW - Thermodynamics KW - High-Entropy Alloys KW - Grain Boundary Segregation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508827 DO - https://doi.org/10.1103/PhysRevMaterials.4.053603 VL - 4 IS - 5 SP - 053603 PB - American Physical Society AN - OPUS4-50882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - da Silva, A. A1 - McEniry, E. A1 - Gault, B. A1 - Neugebauer, J. A1 - Raabe, D. T1 - Segregation-assisted spinodal and transient spinodal phase separation at grain boundaries N2 - Segregation to grain boundaries affects their cohesion, corrosion, and embrittlement and plays a critical role in heterogeneous nucleation. In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries, here, we apply a density-based phase-field model. The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data, while the grain-boundary-density profile is obtained using atomistic simulations. To benchmark the performance of the model, Mn grain-boundary segregation in the Fe–Mn system is studied. 3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions. We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm. The jump corresponds to a spinodal Phase separation at grain boundary. For alloy compositions above the jump, we reveal an interfacial transient spinodal phase separation. The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries. The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries. KW - Grain Boundary Spinodal KW - Densty-based Thermodynamics KW - Microstrucrue Design PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519497 DO - https://doi.org/10.1038/s41524-020-00456-7 VL - 6 IS - 1 SP - 191 PB - Nature AN - OPUS4-51949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maaß, Robert T1 - Tracing structural dynamics in metallic glasses during cryogenic cycling N2 - Highly unrelaxed structural states of metallic glasses have often advantageous mechanical properties. Since metallic glasses continuously relax with time (age) or inherently are well relaxed after processing, methods to uniformly rejuvenate the material are needed. One approach that has received attention is the so-called cryogenic-cycling method, during which a metallic glass is repeatedly immersed into liquid nitrogen. In some cases, cryogenic cycling is truly efficient in increasing the stored excess enthalpy of metallic glasses, but it does not seem to be universally applicable to all alloys and structural states. The origins for these differences remain unclear due to our limited understanding of the underlying structural evolution. In order to shed more light onto the fundamental structural processes of cryogenic cycling, we pursue in-situ x-ray photon correlation spectroscopy (XPCS) to trace the atomic-scale structural dynamics of a Zr-based metallic glass in two different structural states (ribbon and bulk metallic glass). This method allows calculating the relaxation times as a function of time throughout the thermal cycling. It is found that the investigated glasses exhibit heterogeneous structural dynamics at 300 K, which changes to monotonic aging at 78 K. Cryogenic cycling homogenizes the relaxation time distribution for both structural states. This effect is much more pronounced in the ribbon, which is the only structural state that rejuvenates upon cycling. We furthermore reveal how fast atomic-scale dynamics is correlated with long-time average structural relaxation times irrespective of the state, and that the ribbon exhibits unexpected additional fast atomic-scale relaxation in comparison to the plate material. Overall, a picture emerges that points towards heterogeneities in fictive temperature as a requirement for cryogenic energy storage. T2 - MRS Fall 2020 - Invited Talk CY - Boston, MA, USA DA - 27.11.2020 KW - Relaxation metallic glasses PY - 2020 AN - OPUS4-59542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bayerlein, Bernd T1 - Focused ion beam techniques beyond the ordinary - Methodological developments within ADVENT N2 - This poster presents the focused ion beam preparation methodologies developed within the framework of the EU funded EURAMET project ADVENT (Advanced Energy-Saving Technology). It summarises the key breakthroughs achieved for various in situ investigation techniques, e.g. in situ experiments at the Synchrotron facility BESSY II (IR-SNOM and XRS), TEM and SMM instrumentation. The created experimental devices from diverse thin-film semiconductor materials paved the way to dynamic structural studies bearing the potential to determine nanoscale correlations between strain and electric fields and, moreover, for the fundamental development of new in situ capabilities. N2 - Dieses Poster zeigt die FIB Präparationstechniquen, die im Rahmen des EU-finanzierten EURAMET-Projekts ADVENT (Advanced Energy Saving Technology) entwickelt wurden. Es fasst die wichtigsten Errungenschaften zusammen, die für verschiedene in situ Untersuchungstechniken erzielt wurden, z.B. situ-Experimente in dem Synchrotronring BESSY II (IR-SNOM und XRS), in situ TEM Experimente und für die SMM Technik. Die experimentellen Probenstrukturen, die aus verschiedenen Dünnschicht-Halbleitermaterialien erzeugt wurden, ebneten den Weg für dynamische Strukturstudien, die das Potenzial haben, nanoskalige Korrelationen zwischen Dehnung und elektrischen Feldern zu bestimmen und darüber hinaus neue in situ Messmethoden zu entwickeln. T2 - Final Meeting CY - Online Meeting DA - 30.06.2020 KW - FIB KW - Sample preparation KW - In situ KW - TEM KW - AFM PY - 2020 AN - OPUS4-51606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koclega, Damian A1 - Radziszewska, A. A1 - Dymek, S. A1 - Morgiel, J. A1 - Maj, L. A1 - Kranzmann, Axel T1 - Improvement of Corrosion Resistance of 13CrMo4-5 Steel by Ni-Based Laser Cladding Coatings N2 - The 13CrMo4-5 ferritic steel is commonly used in power plants, due to its favorable mechanical properties. According to EN 10028-2, this steel can be used at temperatures up to 570°C because of its creep behavior. The inefficient corrosion resistance limits the application of this steel to lower temperatures depending on the gas temperature and slag formation. Therefore, the application of a highly resistant Ni-based coating is proposed to extend the corrosion resistance of elements made of ferritic steel. The corrosion test was performed in an environment containing a mixture of gases, like O2, COx, and SOx, and deposited ashes with elements, e.g., Na, Cl, Ca, Si, C, Fe, and Al. The exposure time was, respectively, 240 h, 1000 h and 4500 h at a temperature of 600°C. The oxide scale formed on the 13CrMo4-5 steel was significantly thicker than on the IN686 coating. The microstructure and chemical and phase compositions of the oxide scale were investigated using light optical microscopy together with scanning and transmission electron microscopy techniques. Energy dispersive x-ray analyses were performed when appropriate. KW - Aggressive environments KW - Corrosion resistance KW - High - temperature KW - Inconel 686 KW - Laser cladding PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514289 DO - https://doi.org/10.1007/s11665-020-04867-x SN - 1059-9495 VL - 29 IS - 6 SP - 3702 EP - 3713 PB - Springer AN - OPUS4-51428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert A1 - Winkelmann, A. T1 - About the reliability of EBSD measurements: Data enhancement N2 - An extensive set of information about the diffracting volume is carried by EBSD patterns: the crystal lattice, the reciprocal lattice, the crystal structure, the crystal symmetry, the mean periodic number of the diffracting phase, the source point from where it has been projected (projection centre), the crystal orientation, the sample topography (local tilt), the (preparation) quality of defect density of the crystal, and possible pattern overlaps. Some of this information is used regularly in conventional EBSD analyses software while others are still waiting for a more widespread application. Despite the wealth of information available, the accuracy and precision of the data that are presently extracted from conventional EBSD patterns are often well below the actual physical limits. Using a selection of example applications, we will demonstrate the gain in angular resolution possible using relatively low-resolution patterns of approximately 20k pixels in combination with pattern matching (PM) approaches. In this way, fine details in a microstructure can be revealed which would otherwise be hidden in the orientation noise. KW - EBSD KW - Orientation precision KW - Disorientation KW - Grain boundary KW - Phase transformation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521618 DO - https://doi.org/10.1088/1757-899X/891/1/012018 VL - 891 SP - 012018 PB - IOP Science AN - OPUS4-52161 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cios, G. A1 - Nolze, Gert A1 - Winkelmann, A. A1 - Tokarski, T. A1 - Hielscher, R. A1 - Strzalka, R. A1 - Buganski, I. A1 - Wolny, J. A1 - Bala, P. T1 - Approximant-based orientation determination of quasicrystals using electron backscatter diffraction N2 - Orientation mapping of quasicrystalline materials is demonstrated using crystalline approximant structures in the technique of electron backscatter diffraction (EBSD). The approximant-based orientations are symmetrised according to the rotational point group of the quasicrystal, including the visualization of orientation maps using proper colour keys for quasicrystal symmetries. Alternatively, approximant-based orientation data can also be treated using pseudosymmetry post-processing options in the EBSD system software, which enables basic grain size estimations. Approximant-based orientation analyses are demonstrated for icosahedral and decagonal quasicrystals. KW - EBSD KW - Quasicrystal KW - Approximant KW - Chrystal orientation KW - Data processing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514221 DO - https://doi.org/10.1016/j.ultramic.2020.113093 VL - 218 SP - 113093 PB - Elsevier B.V. AN - OPUS4-51422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gadelmeier, C. A1 - Haas, S. A1 - Lienig, T. A1 - Manzoni, Anna Maria A1 - Feuerbacher, M. A1 - Glatzel, U. T1 - Temperature Dependent Solid Solution Strengthening in the High Entropy Alloy CrMnFeCoNi in Single Crystalline State N2 - The main difference between high entropy alloys and conventional alloys is the solid solution strengthening effect, which shifts from a single element to a multi-element matrix. Little is known about the effectiveness of this effect at high temperatures. Face-centered cubic, equiatomic, and single crystalline high entropy alloy CrMnFeCoNi was pre-alloyed by arc-melting and cast as a single Crystal using the Bridgman process. Mechanical characterization by creep testing were performed at temperatures of 700, 980, 1100, and 1200°C at different loads under vacuum and compared to single-crystalline pure nickel. The results allow a direct assessment of the influence of the chemical composition without any disturbance by grain boundary sliding or diffusion. The results indicate different behaviors of single crystalline pure nickel and CrMnFeCoNi. At 700°C CrMnFeCoNi is more creep-resistant than Ni, but at 980°C both alloys show a nearly similar creep strength. Above 980°C the creep behavior is identical and the solid solution strengthening effect of the CrMnFeCoNi alloy disappears. KW - High entropy alloys KW - Single crystal PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514572 DO - https://doi.org/10.3390/met10111412 VL - 10 IS - 11 SP - 1412 PB - MDPI AN - OPUS4-51457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fantin, Andrea A1 - Orazio Lepore, G. A1 - Manzoni, Anna Maria A1 - Kasatikov, S. A1 - Scherb, T. A1 - Huthwelker, T. A1 - d'Acapito, F. A1 - Schumacher, G. T1 - Short-range chemical order and local lattice distortion in a compositionally complex alloy N2 - This work presents an X-ray absorption spectroscopy study on a single-phase state of the Al8Cr17Co17Cu8Fe17Ni33 compositionally complex alloy, focused on the local crystal structure around each alloying element. The comparison of 1st shell bond lengths, obtained by the analysis of extended X-ray absorption fine structure (EXAFS) measured at the K-edges of each alloying element, indicates that Al8Cr17Co17Cu8Fe17Ni33 crystallizes in a distorted arrangement of an fcc lattice. A modest bond length dependence of the alloying elements with increasing atomic number is observed, with minima and maxima at Cr/Co, and Al/Cu, respectively. 1st shell bond lengths spread over ~0.03 Å; consequently, such variations cannot result in lattice distortions greater than ~0.04 Å. EXAFS results clearly indicate short-range order in the alloy: pairing of Al with Ni and Cu is favored, correlating well with a g’ precipitate composition (Al-Ni-Cu rich) reported in previous work, while Al-Cr bonding is unfavored and no Al-Al pairs are observed. Electronic structure information was obtained through comparison between near-edge regions of alloying Elements and corresponding pure metals. Intensity comparison of K-edge features agree with a charge variation of p states in Al8Cr17Co17Cu8Fe17Ni33, where Ni and Cu act as p states electron acceptors, suggesting an orbital hybridization with Al, responsible for a shrinkage in Al metallic radius in the alloy by 0.17 Å. KW - High entropy alloys KW - EXAFS KW - Compositionally complex alloys PY - 2020 DO - https://doi.org/10.1016/j.actamat.2020.04.034 VL - 193 SP - 329 EP - 337 PB - Elsevier Ltd. AN - OPUS4-50830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -