Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 18: Interfaces

MM 18.4: Vortrag

Dienstag, 2. April 2019, 15:00–15:15, H45

A quantum-mechanical study of connections between tensorial elastic properties and chemical bonds in Σ5(210) grain boundaries in Ni₃Si compound — •Martin Friák¹, Martin Zelený^2,3, Monika Všianská^4,1,5, David Holec⁶, and Mojmír Šob^5,1,4 — ¹Institute of Physics of Materials, Czech Academy of Sciences, Brno, Czech Republic — ²Institute of Materials Science and Engineering, NETME Centre, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic — ³Faculty of Mathematics and Physics, Charles University in Prague, Prague, Czech Republic — ⁴Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic — ⁵Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic — ⁶Department of Materials Science, Montanuniversität Leoben, Leoben, Austria

Using ab initio methods we calculate and analyze (tensorial) anisotropic elastic properties of interface states associated with Σ5(210) grain boundaries (GBs) in cubic L1₂-structure Ni₃Si. In particular, we show that GB variant containing both Ni and Si atoms at the interface is unstable with respect to a shear deformation (one of the elastic constants, C₅₅, is negative). Our elastic-constant analysis allowed us to identify a shear-deformation mode reducing the energy and eventually to obtain mechanically stable ground-state. We further discuss an atomistic origin of this instability in terms of the crystal orbital Hamilton population (COHP) and phonon dispersion calculations. For details see Friák et al. Materials 11 (2018) 2263.