Abstract:On the basis of the Miedema model of heat formation and Toop equation, the reactions between titanium melt and special mold materials have been analyzed and calculated thermodynamically. The refractory molding materials involved in the calculation include such materials as carbides, nitrides and borides that possess high chemical stability and high melting points. The results show that the changes of dissolved Gibbs energy(ΔG) of the reactions are all negative in the temperature range from titanium melting point to 2 300K. This means that the chemical stability of those kinds of molding materials decreases when they contact with titanium melt. Furthermore, considering the high chemical reactivity of titanium melt, the calculation will provide some instructions to choose mold materials for titanium castings.

Key words: titanium　interface reaction　Gibbs free energy　mold　refractory materials