First-principles characterization of the anisotropy of theoretical strength and thestress–strain relation for a TiAl intermetallic compound

Abstract

We perform first-principles computational tensile and compressive tests (FPCTTand FPCCT) to investigate the intrinsic bonding and mechanical properties of aγ-TiAl intermetalliccompound (L 10 structure) using a first-principles total energy method. We found that the stress–strainrelations and the corresponding theoretical tensile strengths exhibit strong anisotropy inthe [001], [100] and [110] crystalline directions, originating from the structural anisotropy ofγ-TiAl.Thus, γ-TiAl is a representative intermetallic compound that includes three totally differentstress–strain modes. We demonstrate that all the structure transitions in the FPCTTand FPCCT result from the breakage or formation of bonds, and this can begeneralized to all the structural transitions. Furthermore, based on the calculations wequalitatively show that the Ti–Al bond should be stronger than the Ti–Ti bond inγ-TiAl.Our results provide a useful reference for understanding the intrinsic bonding and mechanical propertiesof γ-TiAl as a high-temperature structural material.