Structural, electronic, elastic and thermodynamic properties of Al1-xZxNi (Z=Cr, V and x= 0, 0.125, 0.25) alloys: First-principle calculations

Abstract

The AlNi intermetallic compound is one of the most promising engineering materials for high temperature applications. Unfortunately, this compound has low tensile ductility at high temperature which limit its functional applications. We show that alloying the AlNi compound with the Cr or V will improve its tensile ductility and therefore its industrial applications. In this paper, the structural, electronic, elastic and thermodynamic properties of Al1-xZxNi (Z = Cr, V and x = 0, 0.125, 0.25) alloys have been studied by the first principles calculations in the framework of density functional theory. The calculated formation energy and cohesive energy of the alloys show that, all alloys have stable structures. The valence charge density distribution study reveals that, chemical bonds between the Z and Ni atoms in the alloys have the nature of covalent, which improve the brittleness of the AlNi alloys. The calculated Pugh’s ratio (or the Poisson’s ratio), shear and bulk modules show that, the increasing of hardness by increasing the x. Moreover, the ductility of the alloys decreased when the value of x is nonzero. The calculation results show that the Pugh’s (Poisson’s) ratio is higher than 1.75 (0.26), indicating a ductile nature of these alloys. Furthermore, thermodynamic properties of the alloys including Grüneisen parameter, thermal expansion coefficient, bulk modulus, Debye temperature and constant volume heat capacity have been investigated and discussed under different pressures and temperatures.