Simple model for the structure and thermodynamics of liquid alloys with strong chemical interactions. I. Chemical short-range order

The authors present a simple model for the structure and thermodynamics of liquid alloys with strong chemical interactions. Starting from the fact that these systems are characterised by the existence of a non-vanishing ordering potential phi CC =c 1 c 2 ( phi 11 + phi 22 -2 phi 12 ), the authors model the interatomic potentials by a hard-sphere potential for the mean pair interaction phi NN =c 1 2 phi 11 +c 2 2 phi 22 +2c 1 c 2 phi 12 and a hard-sphere potential of the same diameter plus a Yukawa tail for phi CC . The volume forces are calculated in an electron-gas model. Based on the solution of this model in the mean spherical approximation, the authors find analytic expressions for the thermodynamic excess functions and the partial structure factors. They have applied their model to liquid Li-Pb, Li-Ag and Li-Mg alloys and find very good results for the heat and the entropy of formation and good agreement between their structure data and neutron scattering experiments.