Theoretical insights into anisotropies in elastic and thermal properties of ternary β-M4AlN3 (M = V, Nb, Ta) nitrides by first-principles calculations

Abstract In this study, the first-principles calculations were employed to investigate the elastic, thermal properties, and the anisotropies in elastic modulus, Debye temperature and thermal conductivity of the ternary nitrides β-M4AlN3 (M = V, Nb, Ta). The results showed that they are brittle and not potentially superhard materials. The anisotropy indexes, 3D surface constructions and 2D planar projections were employed to characterize the anisotropies in elastic modulus and thermal conductivity. The sequences of anisotropies in both elastic modulus and thermal conductivity are β-V4AlN3 > β-Nb4AlN3 > β-Ta4AlN3. Besides, the sound velocities, Debye temperatures, and anisotropies were also discussed.