Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 3: Topical session (Symposium MM): Hydrogen in Materials

MM 3.8: Vortrag

Montag, 12. März 2018, 13:00–13:15, H 0107

New approaches for in-situ nanoindentation of hydrogen charged alloys: insights on bcc FeCr alloys — •Jazmin Duarte Correa, Xufei Fang, Steffen Brinckmann, and Gerhard Dehm — Max-Planck-Institut für Eisenforshung GmbH, 40479 Düsseldorf, Germany

Understanding hydrogen-microstructure interactions in metallic alloys is needed to prevent hydrogen embrittlement. The failure mechanisms that initiate at the atomic scale with hydrogen absorption and interaction with trap binding sites, can be studied independently by nanoindentation; in-situ charging the sample with hydrogen avoids the formation of concentration gradients due to desorption. Two custom electrochemical cells were built for hydrogen charging while nanoindenting the sample: front-side charging with sample and indenter tip immersed into the electrolyte, and back-side charging where the analyzed region is never in contact with the solution. We discuss the advantages and disadvantages of both approaches during the study of the hydrogen effect on homogeneous nucleation of dislocations in bcc FeCr alloys. A reduction in the pop-in load indicating the yield point with the increase of hydrogen content and formation of multiple pop-ins during nanoindentation provided evidence for the decrease in the resolved shear stress and enhanced dislocations nucleation. Although a similar trend is observed for both strategies, a more pronounced effect is noticed by front-side charging, likely due to surface degradation.