Thermodynamics of liquid Cu-Si and Cu-Zr alloys

The partial and integral enthalpies of mixing of Cu-Si and Cu-Zr melts have been measured by high temperature calorimetry at 1900 ± 10 and 1480 ± 5 K, respectively. In dilute copper solutions (Cu-Si system) and dilute zirconium solutions (Cu-Zr system) anomalous variations of the enthalpy of mixing with compositions have been observed. In the Cu-Si system, in the temperature range from 1600 to 1900 K, a negligibly small temperature dependence of the enthalpy of mixing is observed. A least squares treatment of the data results in the following expressions for the molar partial and integral enthalpy of mixing (in kJ-mol-1). The activities are estimated on the basis of the experimental enthalpy of mixing data using an empirical relation and show a reasonable agreement with experimental activity data. (orig.)