Modeling the elastic anisotropies and mechanical strengths of Ir3X intermetallics

Abstract The elastic anisotropies and mechanical strengths of L1 2 intermetallic compounds Ir 3 X (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 Ir 3 Ta exhibits the largest anisotropy in Young's modulus, Poisson's ratio, and shear modulus, respectively, compared to other two Ir 3 X intermetallics and fcc Ir. The calculated ideal tensile strengths and critical tensile strains of three Ir 3 X intermetallics are all larger than those of fcc Ir, indicating that the L1 2 Ir 3 X phase is mechanically harder and less brittle. Moreover, the ideal shear strengths at large strains of L1 2 Ir 3 X are examined and the obtained results suggest that the lattice instability of Ir 3 X 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.