Bulk and surface properties of liquid In-Cu alloys

In-Cu is a weak interacting system (the excess free energy of mixing G_M^xs≈-0.2RT at equiatomic composition) but the composition dependence of the thermodynamic properties exhibit interesting features. G_M^xs is negative in the Cu-rich region and positive for the In-rich end. Similarly other thermodynamic properties are asymmetric about the equiatomic composition. Such an interesting feature is explained here on the basis that a complex of the form Cu₄In exists in the bulk phase. Its energetics are used to study the surface composition of the In-Cu liquid alloys. Our study indicates that the surface is enormously rich with indium concentrations throughout the composition of the alloys.