First-principles study of elastic and electronic properties of MgZn2 and ScZn2 phases in Mg-Sc-Zn alloy

The structural, electronic and elastic properties of typical hexagonal-close-packed MgZn2 and ScZn2 phases in Mg-Sc-Zn alloy were investigated by means of first-principles calculations within the framework of density functional theory (DFT). The calculated lattice constants were in good agreement with the experimental values. The obtained cohesive energy and formation enthalpy of both phases are negative, showing their structural stability from energetic point of view. The five independent elastic constants were calculated, and then the bulk modulus B. shear modulus G, Young's modulus E and Poisson's ratio v of polycrystalline aggregates were derived. The ductility and plasticity of the MgZn2 and ScZn2 phases were further discussed. The elastic anisotropy of the two phases was also analyzed. Finally, the electronic density of states (DOS) and charge density distribution were also calculated to reveal the underlying mechanism of structural stability and mechanical properties. (C) 2010 Elsevier B.V. All rights reserved.