First principle study on the temperature dependent elastic constants, anisotropy, generalized stacking fault energy and dislocation core of NiAl and FeAl

Abstract

The elastic constants, generalized stacking fault energies, and surface energies of NiAl and FeAl have been investigated by using the first principles methods combined with a quasiharmonic approach. Pugh ratio, Cauchy pressure, elasticity anisotropy and Rice ratio are presented at different temperature. It is interesting to find that the anisotropy of NiAl decreases with increasing temperature, but FeAl increases. NiAl has better ductility than FeAl according to the Pugh ratio and the Cauchy pressure. However, the Rice ratio shows the opposite result. Furthermore, the dislocation core structure of NiAl and FeAl is also presented based on an improved Peierls–Nabarro theory.