TY - CONF A1 - Rhode, Michael A1 - Wetzel, Annica A1 - Oczan, Ozlem A1 - Nietzke, Jonathan A1 - Richter, Tim A1 - Schröpfer, Dirk T1 - Hydrogen diffusion and local Volta potential in high- and medium-entropy alloys N2 - High-entropy alloys (HEAs) are characterized by a solid solution of minimum five and medium-entropy alloys (MEAs) of minimum three principal alloying elements in equiatomic proportions. They show exceptional application properties, such as high-strength and ductility or corrosion resistance. Future HEA/MEA-components could be exposed to hydrogen containing environments like vessels for cryogenic or high-pressure storage where the hydrogen absorption and diffusion in these materials is of interest. In our study, we investigated the HEA Co20Cr20Fe20Mn20Ni20 and the MEA Co33.3Cr33.3Ni33.3. For hydrogen ingress, cathodic charging was applied and diffusion kinetic was measured by high-resolution thermal desorption spectros-copy using different heating rates up to 0.250 K/s. Peak deconvolution resulted in high-temperature desorption peaks and hydrogen trapping above 280 °C. A total hydrogen concentration > 40 ppm was identified for the MEA and > 100 ppm for HEA. This indicates two important effects: (1) delayed hydrogen diffusion and (2) considerable amount of trapped hydrogen that must be anticipated for hydrogen assisted cracking phenomenon. Local electrochemical Volta potential maps had been measured for the hydrogen free condition by means of high-resolution Scanning Kelvin Probe Force Microscopy (SKPFM). T2 - Symposium on Materials and Joining Technology CY - Online meeting DA - 07.09.2020 KW - Hydrogen KW - High-entropy alloy KW - Diffusion KW - Scanning kelvin probe force microscopy KW - Corrosion PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511684 DO - https://doi.org/10.1088/1757-899X/882/1/012015 VL - 882 SP - 1 EP - 15 PB - IOP Publishing CY - Bristol AN - OPUS4-51168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falk, Florian A1 - Sobol, Oded A1 - Stephan-Scherb, Christiane T1 - The impact of the microstructure of Fe-16Cr-0.2C on high-temperature oxidation – sulphidation in SO2 N2 - This study elucidates the impact of the microstructure of Fe-16Cr-0.2C on oxide layer formation at 650 ◦C in Ar-0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. The samples were characterised in detail from microstructural and chemical perspectives using scanning electron microscopy (SEM), X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microstructural modification of the alloy by heat-treatment was advantageous. It was found that Cr-carbides support chromia formation and reduce sulphidation when their area fraction is low and diameter is small. KW - Steel KW - Iron KW - SIMS KW - SEM KW - High temperature corrosion KW - Oxidation KW - Sulphidation PY - 2021 DO - https://doi.org/10.1016/j.corsci.2021.109618 VL - 190 SP - 109618 PB - Elsevier Ltd. AN - OPUS4-53001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Hänninen, H. A1 - Böllinghaus, Thomas T1 - In-situ ToF-SIMS analyses of deuterium re-distribution in austenitic steel AISI 304L under mechanical load N2 - Hydrocarbons fuel our economy. Furthermore, intermediate goods and consumer products are often hydrocarbon-based. Beside all the progress they made possible, hydrogen-containing substances can have severe detrimental effects on materials exposed to them. Hydrogen-assisted failure of iron alloys has been recognised more than a century ago. The present study aims to providing further insight into the degradation of the austenitic stainless steel AISI 304L (EN 1.4307) exposed to hydrogen. To this end, samples were electrochemically charged with the hydrogen isotope deuterium (2H, D) and analysed by scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). It was found that deuterium caused a phase transformation from the original γ austenite into ε- and α’-martensite. Despite their low solubility for hydrogen, viz. deuterium, the newly formed phases showed high deuterium concentration which was attributed to the increased density of traps. Information about the behaviour of deuterium in the material subjected to external mechanical load was gathered. A four-point-bending device was developed for this purpose. This allowed to analyse in-situ pre-charged samples in the ToF-SIMS during the application of external mechanical load. The results indicate a movement of deuterium towards the regions of highest stress. KW - ToF-SIMS KW - Hydrogen KW - Deuterium KW - AISI 304L KW - EBSD PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505142 DO - https://doi.org/10.1038/s41598-020-60370-2 VL - 10 IS - 1 SP - 3611 PB - Nature AN - OPUS4-50514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Steiner, S. A1 - Heldt, J. A1 - Sobol, Oded A1 - Unger, Wolfgang A1 - Frömeling, T. T1 - Influence of oxygen vacancies on core-shell formation in solid solutions of (Na,Bi)TiO3 and SrTiO3 N2 - Solid solutions of (Na,Bi)TiO3 (NBT) and SrTiO3 (ST) are materials of interest for high-strain or high-energy density capacitor applications. Often, they exhibit chemical heterogeneity and develop core-shell structures during regular solid-state synthesis with an NBT-rich core. In this case, the NBT forms first so that the strontium needs to diffuse into the material to reach chemical homogeneity. Depending on the presence of core-shell structures, the electrical properties can vary drastically. In this work, we rationalize the effect of variations in oxygen vacancy concentration by Fe-acceptor and Nb-donor doping. It can be shown that a diffusion couple of strontium and oxygen is responsible for chemical homogenization and that the oxygen vacancy content can control the formation of a core-shell structure. KW - Lead-free ceramics KW - Bismuth titanates KW - Core-shell structures KW - Diffusion/diffusivity KW - Ferroelectricity/ferroelectric materials PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525988 DO - https://doi.org/10.1111/jace.17845 SP - 1 EP - 10 PB - Wiley Periodicals LLC, John Wiley & Sons, Inc. AN - OPUS4-52598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Wasserstoffdiffusion und lokale Volta-Potentiale in Hoch- und Mittelentropie-Legierungen N2 - Hochentropie-Legierungen (HEAs) zeichnen sich durch einen Mischkristall-System aus mindestens fünf und Mittelentropie-Legierungen (MEAs) durch mindestens drei Hauptlegierungselemente aus, in äquiatomarer Zusammensetzung. Sie zeigen außergewöhnliche Anwendungseigenschaften, wie z.B. hohe Festigkeit, Duktilität oder Korrosionsbeständigkeit. Zukünftige HEA/MEA-Komponenten aufgrund ihrer Eigenschaften für wasserstoffhaltige Umgebungen (wie Behälter für kryogene oder Hochdruckspeicherung) von Interesse. Daher ist die Bewertung der Wasserstoffabsorption und die Diffusion in diesen Materialien von großer Bedeutung. Dazu wurden in unserer Studie eine CoCrFeMnNi-HEA und eine CoCrNi-MEA untersucht. Die Proben wurden elektrochemisch mit Wasserstoff beladen. Für die Ermittlung des Wasserstoffdiffusionsverhaltens wurde die thermische Desorptionsanalyse (TDA) mit unterschiedlichen Heizraten bis zu 0,250 K/s angewandt. Die nachfolgende Peakentfaltung der Signale führte zu Hochtemperatur-Desorptionsspitzen und Wasserstofftrapping auch über 280°C. Eine resultierende Gesamtwasserstoffkonzentration > 40 ppm wurde für den MEA ermittelt und > 100 ppm für den HEA. Dies deutet auf zwei wichtige Effekte hin: (1) verzögerte Wasserstoffdiffusion und (2) eine beträchtliche Menge an getrapptem Wasserstoff auch bei hoher Temperatur. Beide Effekte können hinsichtlich einer wasserstoffunterstützten Rissbildung kritisch werden, dies erfordert jedoch weitere Untersuchungen. Zusätzlich erfolgte die Bestimmung des lokalen Volta-Potentials mittels hochauflösender Kelvin-Sonden-Kraft-Mikroskopie (SKPFM). Die ermittelten Scans zeigen einen bestimmten Einfluss der Wasserstoffbeladung auf die Potentiale. T2 - Symposium on Materials and Joining Technology CY - Online meeting DA - 07.09.2020 KW - Wasserstoff KW - High-entropy alloy KW - Diffusion KW - Scanning kelvin probe force microscopy KW - Thermal desorption analysis PY - 2020 AN - OPUS4-51187 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meinderink, D. A1 - Kielar, C. A1 - Sobol, Oded A1 - Ruhm, L. A1 - Rieker, F. A1 - Nolkemper, K. A1 - Orive, A. G. A1 - Özcan Sandikcioglu, Özlem A1 - Grundmeier, G. T1 - Effect of PAA-induced surface etching on the adhesion properties of ZnO nanostructured films N2 - Zinc oxide - polymer interfaces are known to exhibit interesting properties regarding molecular adhesion. This work is aimed at the investigation of the effect of the morphology and surface chemistry on the macroscopic adhesion of a model epoxy-based adhesive to nanorod (ZnO NR) and nanocrystalline (ZnO NC) ZnO-modified surfaces. Both ZnO films have been prepared using hydrothermal synthesis on hot-dip galvanized steel (HDG) surfaces by varying the precursor chemistry in order to control the film morphology. Poly (acrylic acid) (PAA) was used to improve the interfacial adhesion by modifying the morphology and surface chemistry of ZnO nanostructured films. The strong interaction of PAA from a dilute and neutral aqueous solution with the ZnO nanocrystallites was shown to significantly improve the interfacial adhesion by means of a nanoetching process. It was shown that the wet peel-forces correlate well with the considered morphology and surface chemistry. KW - Interfacial stability KW - Morphology control KW - Poly(acrylic acid) KW - Adhesion by mechanical interlocking KW - ZnO films KW - ZnO nanorods Nanocrystalline PY - 2021 DO - https://doi.org/10.1016/j.ijadhadh.2021.102812 SN - 0143-7496 VL - 106 SP - 102812 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-52600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wetzel, Annica T1 - Corrosion Properties and Protective Oxide Film Characteristics of CrMnFeCoNi High Entropy Alloy and CrCoNi Medium Entropy Alloy N2 - High and medium entropy alloys gained increasing academic and industrial interest as novel materials for engineering applications. This project is aiming to clarify and compare the general and local corrosion properties of high entropy alloy CrMnFeCoNi and medium entropy alloy CrCoNi in different aqueous environments. The focus lies on the local corrosion processes that result either from microstructural imperfections (inclusions, defects at grain boundaries etc.) in the base material or processing related changes in the microstructure and/or local composition. The corrosion behavior of the alloys was monitored via potentiodynamic polarization experiments and the local corrosion characteristics were further investigated by means of scanning electrochemical microscopy (SECM). Their passivation behavior was analyzed in two different electrolyte systems (NaCl and H2SO4 c = 0.1M). The characterization of the surface morphology and composition of the passive film was performed by means of atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM/EDX) and X-Ray photoelectron spectroscopy (XPS), respectively. To analyze the semiconducting properties of the passive film Mott-Schottky analysis was conducted. Considering long term corrosion effects, electrochemical work was supported with immersion tests and the analysis of corrosion products by SEM/EDX, ICP-MS and XPS depth-profiling. Our results indicate that the medium entropy alloy CrCoNi has a significantly higher corrosion resistance due to the higher concentration of chromium in comparison to the high entropy alloy CrMnFeCoNi. The presentation will summarize our results on the mechanistical aspects of the observed high corrosion resistance. T2 - ISE Annual 72nd meeting CY - Online meeting DA - 29.08.2021 KW - High Entropy Alloys KW - Aqueous Corrosion KW - Medium Entropy Alloys KW - Atomic Forc Microscopy KW - Scanning Kelvin Probe Force Microscopy KW - Potentiodynamic Polarization KW - Electrochemical Impedance Spectroscopy KW - ICP-MS PY - 2021 AN - OPUS4-53789 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wetzel, Annica T1 - Local corrosion properties of high/medium entropy alloys in aqueous environments N2 - High and medium entropy alloys gained increasing academic and industrial interest as novel materials for engineering applications. This project is aiming to clarify and compare the general and local corrosion properties of high entropy alloy CrMnFeCoNi and medium entropy alloy CrCoNi in different aqueous environments. The focus lies on the local corrosion processes that result either from microstructural imperfections (inclusions, defects at grain boundaries etc.) in the base material or processing related changes in the microstructure and/or local composition. The corrosion behavior of the alloys was monitored via potentiodynamic polarization experiments and the local corrosion characteristics were further investigated by means of scanning electrochemical microscopy (SECM). Their passivation behavior was analyzed in three different electrolyte systems (NaCl, H2SO4 and NaClO4; c = 0.1M). The characterization of the surface morphology and composition of the passive film was performed by means of atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM/EDX) and X-Ray photoelectron spectroscopy (XPS), respectively. Considering long term corrosion effects, electrochemical work was supported with immersion tests and the analysis of corrosion products by SEM/EDX and XPS depth-profiling. Our results indicate that the medium entropy alloy CrCoNi has a significantly higher corrosion resistance in comparison to the high entropy alloy CrMnFeCoNi. The presentation will summarize some of our results on the mechanistical aspects of the observed high corrosion resistance. T2 - EUROCORR 2020 CY - Online meeting DA - 07.09.2020 KW - High Entropy Alloys KW - Corrosion KW - Medium Entropy Alloys KW - Atomic Forc Microscopy KW - Scanning Kelvin Probe Force Microscopy KW - Potentiodynamic Polarization PY - 2020 AN - OPUS4-53787 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wetzel, Annica T1 - Corrosion Properties and Protective Oxide Film Characteristics of CrMnFeCoNi High Entropy Alloy and CrCoNi Medium Entropy Alloy N2 - High and medium entropy alloys gained increasing academic and industrial interest as novel materials for engineering applications. This project is aiming to clarify and compare the general and local corrosion properties of high entropy alloy CrMnFeCoNi and medium entropy alloy CrCoNi in different aqueous environments. The focus lies on the local corrosion processes that result either from microstructural imperfections (inclusions, defects at grain boundaries etc.) in the base material or processing related changes in the microstructure and/or local composition. The corrosion behavior of the alloys was monitored via potentiodynamic polarization experiments and the local corrosion characteristics were further investigated by means of scanning electrochemical microscopy (SECM). Their passivation behavior was analyzed in three different electrolyte systems (NaCl, H2SO4 and NaClO4; c = 0.1M). The characterization of the surface morphology and composition of the passive film was performed by means of atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM/EDX) and X-Ray photoelectron spectroscopy (XPS), respectively. Considering long term corrosion effects, electrochemical work was supported with immersion tests and the analysis of corrosion products by SEM/EDX and XPS depth-profiling. Our results indicate that the medium entropy alloy CrCoNi has a significantly higher corrosion resistance due to the higher concentration of Chromium in comparison to the high entropy alloy CrMnFeCoNi. The presentation will summarize our results on the mechanistical aspects of the observed high corrosion resistance. T2 - EUROCORR 2021 CY - Online meeting DA - 20.09.2021 KW - High Entropy Alloys KW - Aqueous Corrosion KW - Medium Entropy Alloys KW - Atomic Forc Microscopy KW - Scanning Kelvin Probe Force Microscopy KW - Potentiodynamic Polarization KW - Electrochemical Impedance Spectroscopy KW - ICP-MS PY - 2021 AN - OPUS4-53791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wetzel, Annica T1 - Corrosion Properties and Protective Oxide Film Characteristics of CrMnFeCoNi High Entropy Alloy and CrCoNi Medium Entropy Alloy N2 - High and medium entropy alloys gained increasing academic and industrial interest as novel materials for engineering applications. This project is aiming to clarify and compare the general and local corrosion properties of high entropy alloy CrMnFeCoNi and medium entropy alloy CrCoNi in different aqueous environments. The focus lies on the local corrosion processes that result either from microstructural imperfections (inclusions, defects at grain boundaries etc.) in the base material or processing related changes in the microstructure and/or local composition. The corrosion behavior of the alloys was monitored via potentiodynamic polarization experiments and the local corrosion characteristics were further investigated by means of scanning electrochemical microscopy (SECM). Their passivation behavior was analyzed in three different electrolyte systems (NaCl, H2SO4 and NaClO4; c = 0.1M). The characterization of the surface morphology and composition of the passive film was performed by means of atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM/EDX) and X-Ray photoelectron spectroscopy (XPS), respectively. Considering long term corrosion effects, electrochemical work was supported with immersion tests and the analysis of corrosion products by SEM/EDX and XPS depth-profiling. Our results indicate that the medium entropy alloy CrCoNi has a significantly higher corrosion resistance due to the higher concentration of Chromium in comparison to the high entropy alloy CrMnFeCoNi. The presentation will summarize our results on the mechanistical aspects of the observed high corrosion resistance. T2 - EuroMat 2021 CY - Online meeting DA - 12.09.21 KW - High Entropy Alloys KW - Aqueous Corrosion KW - Medium Entropy Alloys KW - Atomic Forc Microscopy KW - Scanning Kelvin Probe Force Microscopy KW - Potentiodynamic Polarization KW - Electrochemical Impedance Spectroscopy KW - ICP-MS PY - 2021 AN - OPUS4-53790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -