Modeling the elastic anisotropies and mechanical strengths of Ir3X intermetallics

Abstract

The elastic anisotropies and mechanical strengths of L12 intermetallic compounds Ir3X (X = V, Nb, and Ta) in comparison with fcc Ir metal were comprehensively investigated by using first-principles calculations. The elastic anisotropic calculations show that Ir3Ta exhibits the largest anisotropy in Young's modulus, Poisson's ratio, and shear modulus, respectively, compared to other two Ir3X intermetallics and fcc Ir. The calculated ideal tensile strengths and critical tensile strains of three Ir3X intermetallics are all larger than those of fcc Ir, indicating that the L12 Ir3X phase is mechanically harder and less brittle. Moreover, the ideal shear strengths at large strains of L12 Ir3X are examined and the obtained results suggest that the lattice instability of Ir3X phase occurs at the (111)〈1¯10〉 directions accompanied by the breaking of Ir-X bonds and the formation of new orthorhombic structure through lattice reconstruction.