Activity calculation from ternary phase diagrams

The activities formulas of all the points, lines and areas were calculated from the eight typical ternary phase diagrams by means of the melting point free energy method, standard free energy of formation method and chemical equilibrium method. No assumptions and approximations were introduced. The eight typical phase diagrams studied almost cover the whole range of ternary phase diagrams. The calculation methods and formulas could be applied to all kinds of complicated ternary phase diagrams. Additionally, this method could also be widely applied to the ternary isothermal section phase diagrams and multi-component phase diagrams.