First-principles study of the elastic and mechanical properties of Ni 3 Al under high pressure

A first-principles study of the structural and elastic properties of the intermetallic compound Ni3Al was undertaken, exploiting density-functional theory and generalized gradient approximation (GGA). The elastic constants C11, C12, and C44 were shown to be sufficiently close to the density of the k-point mesh in the deformed Brillouin zone to conclude that the elastic anisotropy of the coefficient A increases as the pressure increases. Young’s modulus of Ni3Al along {100} is approximately two times higher than that along {111}. The computed elastic constants from first principles satisfy C11 > C12 > C44, which are in good agreement with the experiment data. The cubic Ni3Al possesses a bulk modulus of 312 GPa, comparable to that of cubic hafnium nitride. Theoretical calculations for Ni3Al show that all elastic moduli increase monotonically as the pressure increases. These results suggest there are potential technological applications of such materials in extreme environments.