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MM: Fachverband Metall- und Materialphysik

MM 19: Invited Talk Fritz Körmann

MM 19.1: Hauptvortrag

Mittwoch, 7. September 2022, 09:30–10:00, H44

High-Entropy Alloys: Materials design in high dimensional chemical space from ab initio thermodynamics — •Fritz Körmann — Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany — Materials Science and Engineering, Delft Uni- versity of Technology, 2628 CD, Delft, The Netherlands

A well-targeted design of modern alloys such as high entropy alloys (HEAs) is extremely challenging due to their immense composition space. In this talk I will discuss recent advances in fully parameter- free ab initio calculations combining advanced statistical concepts and machine learning techniques. These novel techniques allow to compu- tationally identify favorable composition islands in the high dimension chemical phase space solely on the computer. Using this approach, various mechanisms and concepts proposed in the literature have been tested: Besides lattice distortions, stacking-fault energies (SFEs) have been successfully used as a descriptor to link atomistic simulations to the macroscopic deformation mechanisms that are behind the su- perior mechanical performance. Interstitial alloying with C reveals, e.g., large fluctuations in solution energies depending on the specific local chemical environment and its impact on SFEs can be even qual- itatively different depending on alloy composition. We also discuss BCC-HCP stability as promising descriptor to identify mechanically appealing refractory HEAs and the critical role of lattice distortions therefore. Based on these computationally highly expensive computa- tions easy-to-use materials design rules will be derived and discussed for the various examples.