Thermodynamic assessment of the Cu–Ti–Zr system

Abstract

Equilibrium phase relations in the Cu–Ti–Zr system are calculated using the Calphad approach. Thermodynamic model parameters for the Ti–Zr, Cu–Ti and Cu–Zr systems, previously obtained in the literature, are used. New thermodynamic descriptions for the ternary interaction parameters of the liquid are obtained from experimental information. Additionally, the Gibbs energy of formation for the ternary phase Cu 2TiZr phase is also assessed from experimental data. A new description of the CuTi 2 and CuZr 2 phases, treated as single phases, is developed. The parameters obtained in this assessment are later used for the calculation of selected isothermal sections and the projected liquidus surface of this system over the entire composition range. This model allows the prediction of a series of invariant points involving the liquid phase, at lower temperatures than neighboring binary eutectics.