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 x_Zr = 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.