The thermodynamic re-assessment of the Cu–Zr system

Based on all the available experimental phase equilibrium and thermochemical data, the Cu–Zr system has been thermodynamically reassessed by means of the CALPHAD (CALculation of PHAse Diagrams) technique. The substitutional solution model was used to describe the liquid and three terminal solid solutions, fcc-A1(Cu), bcc-A2(βZr) and hcp-A3(αZr), and their excess Gibbs energies were formulated with the Redlich–Kister polynomial. Ten intermediate compounds, Cu9Zr2, Cu51Zr14, Cu8Zr3, Cu2Zr, Cu24Zr13, Cu10Zr7, CuZr, Cu5Zr8, CuZr2-h and CuZr2-l, were contained in the system, and were treated as stoichiometric phases. For the phase CuZr2, there are the high and the low temperature modifications. The parameters of all the Gibbs energy expressions were optimized. A set of self-consistent thermodynamic parameters has been obtained. The calculated phase diagram and thermodynamic properties agree well with the available experimental data.