Abstract:Based on the appearance of minima of mixing free energy and maxima (or minima)of excess free energy. formation of compound or short-range order in the solid state, exhibition of miscibility gap,two phase region or eutectoid in the solid(or liquid) state as well as symmetrical or unsymmetrical deviations of activity relative to Raoultian behavior, calculating models of mass action concentrations for Si-Ge, Ni-Pb, Fe-Cr, Fe-Cu, Sb-Sn and Ag-Au as well as Ni-Pt, Cr-V and Ag-pb metallic melts have been formulated. Good agreement between calculated and measured values shows that the calculating models reflect the structural characteristics of given metallic melts.

Key words: activity short-range order coexistence theory mass action concentration