First principles investigation of the binary intermetallics in Pb-Mg-Al alloy: Stability, elastic properties and electronic structure

First principles calculations have been carried out to investigate the structural stability, elastic properties, Debye temperature and electronic structure of the main binary cubic phases Mg17Al12 and Mg2Pb with A(12) and C-12 structures in the new type Pb-Mg-Al alloy, respectively. The optimized structural parameters were largely consistent with the experimental values. Cohesive energy and formation enthalpy showed that the Mg17Al12 and Mg2Pb are of the strong structural stability as well as good alloying ability. The electronic density of states (DOS) was given. Three independent single-crystal elastic constants (C-11, C-12 and C-44) at zero pressure as well as polycrystalline elastic parameters such as bulk modulus B, Young's modulus E, shear modulus G, Poisson's ratio v and anisotropy value A for both phases have been calculated by Voigt-Reuss-Hill averaging scheme. The mechanical properties of the cubic phases such as ductility and tenacity were further analyzed and discussed. (C) 2010 Elsevier Masson SAS. All rights reserved.