First-principles studies of Al–Ni intermetallic compounds

The structural properties, heats of formation, elastic properties, and electronic structures of Al–Ni intermetallic compounds are analyzed here in detail by using density functional theory. Higher calculated absolute values of heats of formation indicate a very strong chemical interaction between Al and Ni for all Al–Ni intermetallic compounds. According to the computational single crystal elastic constants, all the Al–Ni intermetallic compounds considered here are mechanically stable. The polycrystalline elastic modulus and Poissonʹs ratio have been deduced by using Voigt, Reuss, and Hill (VRH) approximations, and the calculated ratio of shear modulus to bulk modulus indicated that AlNi, Al3Ni, AlNi3 and Al3Ni5 compounds are ductile materials, but Al4Ni3 and Al3Ni2 are brittle materials. With increasing Ni concentration, the bulk modulus of Al–Ni intermetallic compounds increases in a linear manner. The electronic energy band structures confirm that all Al–Ni intermetallic compounds are conductors.