The mechanical, thermodynamic, and electronic properties of cubic Au4Al crystal via first-principles calculations

Abstract

The mechanical, thermodynamic, and electronic properties of cubic Au4Al intermetallic compound (IMC) crystal were explored through first-principles calculations within the generalized gradient approximation (GGA). The lattice constants and three independent elastic constants of Au4Al crystal were first calculated as a function hydrostatic pressure, and its elastic anisotropy was evaluated by the computation of the crystal direction-dependent elastic modulus and the Zener anisotropy factor. The mechanical characteristics of the crystal, such as its ductile-brittle feature and elastic anisotropy, were also obtained according to its Cauchy pressure, Zener anisotropic factor, and directional Young's modulus. In addition, the influence of hydrostatic pressure on the polycrystalline mechanical properties of Au4Al, including bulk, shear, and Young's moduli; ductility; brittleness; and Vickers hardness characteristics were also estimated. Finally, the temperature-dependent Debye temperature and heat capacity of the IMC crystal was determined using a quasi-harmonic Debye model, and its electronic band structures and density of states profiles were examined through an analysis of its electronic characteristics.The results reveal that the Au4Al crystal is not only an elastically anisotropic, low stiff and very ductile material but also a conductor. Furthermore, the bulk, shear, and Young's moduli; Zener anisotropy factor; ductility; and Vickers hardness of the crystal would increase with an increase in hydrostatic pressure. Finally, it was also found that the heat capacity of Au4Al at low temperature strictly follows the Debye T3 law.