Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 30: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Structure and Deformation II

MM 30.2: Talk

Tuesday, March 21, 2017, 12:00–12:15, BAR 205

Tensorial elastic properties and stability of interface states associated with Σ5(210) grain boundaries in Ni₃(Al,Si) — •Martin Friák^1,2, Monika Všianká^2,1, David Holec³, and Mojmír Šob^2,1,4 — 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 Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, Austria — ⁴Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic

Grain boundaries (GBs) represent one of the most important types of defects in solids. They are challenging for theoretical studies because of their distorted atomic structure. We use ab initio methods to assess tensorial elastic properties of interface states associated with GBs. Focusing on the Σ5(210) GBs in Ni₃Al intermetallics as a case study, we evaluate the mechanical stability of the interface states by checking Born-Huang’s stability criteria. The elastic constant C₅₅ is found three-/five-fold lower than in the bulk and, as a result, the mechanical stability of interface states is reduced. The tensorial elasto-chemical complexity of the interface states is demonstrated by a high sensitivity of elastic constants to the GB composition. In particular, we study elasticity changes induced by Si atoms segregating into the atomic layers close to the GBs and substituting Al atoms. If wisely exploited, our study paves the way towards solute-controlled design of GB-related interface states with tailored stability and/or tensorial properties.