Electronic and dynamical properties of NiAl studied from first principles

Abstract

The electronic structural and dynamical properties of NiAl have been studied using density functional theory and Debye model. The obtained pressure/temperature dependence on the V/V0 and lattice parameter, agrees with the available experimental and other theoretical data. The results show that the ratio of Debye temperature (θp/θ0), velocities of longitudinal and transverse wave (Vl[100], Vl[110], VT1[001] and VT1[010]), anisotropy factors (A[001],(100) and A[001],(110)), Young’s modulus (Y[111]) and Poisson’s ratios (σ[111] and σ[001]) increase with pressure, while the transverse wave velocity (VT2[1−10]), Young’s modulus (Y[001]) and axis compressibility decrease with pressure. But, the ratio of θp/θ0 decreases with temperature. Finally, the elastic anisotropy of NiAl and the smaller shear constant C′ = (C11 − C12)/2, as well as the different character of Young’s moduli and Poisson’s ratios along main directions, result from the strong hybridization effect of Al-p–Ni-d and Ni-d–Ni-d along [111] and [110] directions.