Solubility Product for CuS and Cu2S in Iron

The solubility product formulae of CuS and Cu2S in ferrite and in austenite have been obtained via thermodynamic method, according to the formation energy of CuS and Cu2S and the solubility formulae of elements Cu and S in ferrite and in austenite. By comparing the solubility products for CuS and Cu2S in iron, it is found that Cu2S instead of CuS should be precipitated in iron due to competitative precipitation, in the view of thermodynamics. The formulae of CuS and Cu2S deduced from thermodynamic method would play an important role in related theoretical research and practical production.