Theoretical determination of pair interaction energies for a Mg-Al alloy

Theoretical study of phase stability based on the Cluster Variation Method is extended to a hexagonal lattice. The validity of the developed code is examined in the limits of isotropic interaction and vanishing out-plane interaction. The present results satisfactorily reproduces the ones for an fee lattice and two dimensional triangle lattice. Then, the phenomenological calculations within the mold of Lennard-Jones type pair interaction energies are attempted for Mg-AI alloy system. The pair interaction energies for Mg-Mg and Al-Al are determined by cohesive energies for pure elements, while the one for AlMg is determined based on the experimental free energy of formation of solid solutions at 700K.