Regensburg 2025 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 11: Topical Session: Defects of Defects
MM 11.3: Talk
Tuesday, March 18, 2025, 11:00–11:15, H10
Impact of grain boundary defects on grain boundary diffusion and segregation of Cr in Ni bicrystal — Shraddha Sevlikar1, Mohan G. Muralikrishna1, Daniel Gaertner1, Sergei Starikov2, Tobias Brink3, Daniel Scheiber4, Daria Smirnova3, Daniel Irmer5, Bengü Tas1, Vladimir A. Esin5,6, Vsevolod I. Razumovskiy4, Christian H. Liebscher3,7, Gerhard Wilde1, and •Sergiy Divinski1 — 1Institute of Materials Physics, University of Münster, Germany — 2ICAMS, RU Bochum, Germany — 3MPI for Sustainable Materials, Düsseldorf, Germany — 4Materials Center Leoben Forschung GmbH, Leoben, Austria — 5Mines Paris, PSL University, Évry, France — 6Université de Lorraine, CNRS, Nancy, France — 7RC FEMS, RU Bochum, Germany
Grain boundary diffusion of Cr in a near Sigma-11 Ni bicrystal is measured using the radiotracer technique. Opposite to expectations, two distinct contributions to short-circuit diffusion along the nominally single interface are distinguished and related to the existence of two macroscopic facets with distinct inclinations and, as a result, distinct structures. The segregation factor of Cr in Ni is found to be about unity, which is fully supported by ab initio calculations. Using classical atomistic simulations, Ni grain boundary self-diffusion rates are calculated for the symmetric and asymmetric facets. An accelerated self-diffusion kinetics along the asymmetric facet is observed and attributed to the presence of disconnection-like defects. A heterogeneous mechanisms governing atomic migration across distinct facets is corroborated.
Keywords: diffusion; grain boundary; disconnection; atomistic simulation; segregation