First-principles calculations to investigate mechanical, thermodynamic and electronic properties of Al2CuMg intermetallic compound under pressure effect

Abstract

The effect of pressure on the structural stability, elasticity, electronic properties and thermodynamic properties of the Al2CuMg intermetallic compound in Al–Cu–Mg alloys has been investigated using first-principles calculations. The results indicate that the equilibrium lattice constants, elastic constants and elastic modulus calculated agree with previous theoretical and experimental data at 0 GPa. Moreover, Young's modulus, bulk modulus, shear modulus, B/G values and Poisson's ratio increase with increasing pressure. Notably, the material transforms from brittle to ductile with the pressure increased. Furthermore, the variation tendency of the density of states with pressure is analyzed and the effect of pressure on mechanical properties is explained from the perspective of chemical bonding. Based on the quasi-harmonic Debye model and the Gibbs procedure, the dependence of the thermodynamic parameters on temperature and pressure was obtained for conditions from 0 ∼ 30 GPa to 0 ∼ 1000 K. The results indicate that the heat capacity, coefficient of thermal expansion and entropy of the material increase with rising temperature and reduce with increasing pressure. In this work, the theoretical prediction of the Al2CuMg properties will provide fundamental data and assistance for experimental and further theoretical investigations.