Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 4: Structural Materials

MM 4.6: Vortrag

Montag, 5. September 2022, 11:45–12:00, H46

Ab initio study of magneto-chemo-structural coupling at FeMn grain boundaries — •Omkar Hegde, Jörg Neugebauer, and Tilmann Hickel — Max-Planck-Institut für Eisenforschung, Max-Planck-Strasse 1, 40227 Düsseldorf, Germany

Mn segregation at Fe grain boundaries is known to be a precursor for a variety of phenomena such as embrittlement, spinodal decomposition, phase transformation, etc [1,2]. Therefore, various heat treatments are performed in experiments to control Mn decoration at grain boundaries for *segregation engineering* [1], which could alter the local magnetic state. In this direction, a thorough understanding of the connection between the local magnetic state and segregation remains elusive. In the present work, we tackle this issue by studying segregation in both the ferromagnetic state (low-temperature) and paramagnetic state (high-temperature) using ab initio-based approaches [3]. We demonstrate that the Mn segregation profile is mainly modulated by local magnetic interactions, providing new opportunities for grain boundary segregation engineering. Finally, we show that the formation of grain boundary and Mn segregation can, in turn, tune the local magnetic transition temperature, thereby revealing a complex coupling of structure, chemistry, and magnetism.

[1] D Raabe et al., Current Opinion in Solid State and Materials Science, 18, 253-261 (2014).

[2] AK Da Silva et al., Nature communications, 9, 1-11 (2018).

[3] O Hegde et al., Physical Review B, 102, 144101 (2020).