Density functional theory calculations of the double gamma prime Ni3Ta phase under pressure: Structural, mechanical, and electronic properties

Abstract

In this study, we investigated the structural, mechanical, and electronic properties of the γ′′-Ni3Ta (body-centered tetragonal structure) phase under various pressures using first-principles methods. The negative formation enthalpy indicated that γ′′-Ni3Ta is energetically stable when external pressure is applied. The elastic constant and polycrystalline elastic moduli were calculated using the stress–strain and Voigt–Reuss–Hill approximations methods. The results showed that γ′′-Ni3Ta is mechanically stable and ductile. The mechanical anisotropies of γ′′-Ni3Ta were measured using the elastic anisotropic indexes (AU, AB, and AG, and A1, A2, and A3) and the calculated results suggest that γ′′-Ni3Ta is anisotropic. In addition, the sound velocities and Debye temperatures were calculated. Finally, the electronic densities of states were investigated to determine the internal mechanisms responsible for the structural and mechanical properties of γ′′-Ni3Ta.