Abstract: Based on the phase diagrams, measured activities and the annexation principle, the calculating models of mass action concentrations for Cd-Pb, Pb-Sb and Cd-Sb binary as well as Cd-Pb-Sb ternary metallic melts have been formulated. The results of calculation both agree with practice and obey the mass action law. This in turn testifies that the models formulated can reflect the structural reality of corresponding melts and the annexation principle is applicable to these melts.

Key words: activity, mass action concentration, coexistence theory, annexa tion principle