Abstract: In this paper, the activities of components of Ga-Sb system have been calculated from its phase diagram by using computer program CABPD (calculating activities from binary phase diagrams) presented by us in previous paper. The excess free energy of liquid solution can be expressed as: ΔG_m=X_(Ga)X_(Sb)(4392+17022X_(Sb)-15138X_(Sb)) J/mol In order to verify the reliability of calculated results, a discriminant has been proposed.

Key words: Ga-Sb alloy, thermodynamic properties