Thermodynamic investigation of the Cu–Zr system

High temperature heat contents of the Cu–Zr system alloys were measured over temperature range from 880 to 1470 K using a drop calorimeter. The enthalpies of fusion of some solid compounds were determined by the heat content—temperature plots and the entropies of fusion were calculated. Enthalpies of mixing in the liquid Cu–Zr system were measured by high temperature reaction calorimetry in the concentration range of xZr = 0.182–0.667 at 1443 K. This system has negative enthalpies of mixing over the measured concentration range. The standard enthalpies of formation at 298.15 K of Cu9Zr2, Cu51Zr14, Cu8Zr3, Cu10Zr7 and CuZr2 compounds were determined from the obtained data for the heat contents and enthalpies of mixing. Based on the experimental data, published thermodynamic and phase diagram data, the Cu–Zr binary system was analyzed using Redlich–Kister polynomial equation. The thermodynamic properties and the phase diagram calculated from the optimized parameters agree well with the experimental data.