SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 18: Transport in Materials: Metals, Alloys and Oxides

MM 18.1: Vortrag

Dienstag, 28. März 2023, 11:30–11:45, SCH A 118

Understanding diffusion in high entropy alloys from an experiment-ab initio approach — •Xi Zhang¹, Sergiy Divinski², and Blazej Grabowski¹ — ¹Institute for Materials Science, University of Stuttgart, D-70569 Stuttgart, Germany — ²Institute of Materials Physics, University of Münster, 48149 Münster, Germany

Diffusion in high entropy alloys (HEAs), due to the significant chemical complexity and the severe lattice distortion, has many fundamental features that are extremely important for both basic research and industrial development. The most accurate and direct method to study diffusion is the radiotracer technique whereby a number of intriguing phenomena, e.g., ultra-fast, non-/anti-sluggish diffusion, have been observed. To advance the current understanding of the observed phenomena, accurate theoretical analysis is highly required. The key point of the present approach is the combined measurement of diffusivities and interdiffusion profiles on the one hand and a highly accurate DFT-informed assessment of the diffusion mechanisms on the other. In this way, the long-standing mysteries in HEA diffusion, e.g., "sluggish" diffusion, can be comprehensively examined and understood. Remarkably, we show by investigating an HCP AlScHfTiZr HEA system that the increasing chemical complexity results in a considerably broadened distribution of the defect formation and migration energies which may enhance the mobility of the defects and thus the diffusion rates. The observed "anti-sluggish" diffusion can be traced back to the lattice distortion as revealed by the DFT calculations.