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MA: Fachverband Magnetismus
MA 32: Spin Structures and Magnetic Phase Transitions
MA 32.3: Vortrag
Mittwoch, 18. März 2015, 15:30–15:45, EB 202
Quantum-mechanical study of clean and segregated Σ5(210) grain boundaries in Ni3Al — •Martin Friák1,2, Monika Všianská2,1, and Mojmír Šob2,1,3 — 1Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic — 2Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic — 3Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
Grain boundaries (GBs) represent an important class of two-dimensional extended defects and macroscopic strength of polycrystalline materials depends strongly on their cohesion. It is known that impurities in ppm concentration can drastically change material properties. After our previous study of segregation trends of sp elements in Ni [1], we extend our research to a binary intermetallic compound, Ni3Al. We employ quantum-mechanical methods to study the energetics, magnetism, segregation and strengthening/embrittling tendencies at the Σ5(210) GB. We simulate two different interface stoichiometries of the clean Ni3Al Σ5(210) GB and that one with both Ni and Al atoms present at the interface is found to have a lower energy than that with only Ni atoms. For Si, Ga, Ge, As, Se, In, Sn, Sb and Te segregated to Ni3Al Σ5(210) GB and free (210) surfaces, we perform the relaxation of the geometric configurations with and without impurities and analyze the effect of impurities on the distribution of magnetic moments. [1] M. Všianská and M. Šob, Prog. Mat. Sci. 56 (2011) 817, and Phys. Rev. B 84 (2011) 014418.