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MM: Fachverband Metall- und Materialphysik

MM 21: Transport in Materials: Thermal transport

MM 21.7: Talk

Wednesday, September 7, 2022, 12:00–12:15, H45

Grain boundary diffusion and segregation of Cr in high-purity Ni bi-crystals with a Σ 11 grain-boundary — •D. Gaertner¹, S. V. Sevlikar¹, G. M. Muralikrishna¹, D. Cozlin², D. Irmer², D. Schreiber³, B. Tas¹, M. Vaidya¹, T. Brink⁴, V. E. Esin², C. Duhamel², G. Dehm⁴, V. Razumoskii³, G. Wilde¹, and S. V. Divinski¹ — ¹Institute of Materials Physics, University of Münster, Münster, Germany — ²MINES ParisTech, PSL University, Centre des Matériaux, Évry, France — ³Materials Center Leoben Forschung GmbH (MCL), Austria — ⁴Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany

Grain-boundary diffusion of Cr in a Ni near Σ 11(113)[110] bi-crystal is measured in an extended temperature interval between 503 K and 1303 K using the radiotracer technique. The grain boundary diffusion coefficients, D_gb, and the triple products, P are determined in the C- and B-type kinetic regimes, observing a strong deviation from the otherwise linear Arrhenius-type temperature dependence above 1000 K. The present results substantiate that the segregation factor of Cr in Ni is about unity, being in agreement with the preliminary findings in polycrystalline counterparts measured by SIMS and are fully supported by DFT-based calculations. Extensive MD simulations with empirical interatomic potentials substantiate an extreme stability of the Σ 11 grain-boundary structure in Ni from 0 K up to melting point. The non-linear Arrhenius temperature dependence is interpreted in terms of pronounced anharmonic contributions to defect formation at elevated temperatures.