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

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 (A^U, A_B, and A_G, 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.