Enthalpy of Mixing of Liquid Ni-Zr and Cu-Ni-Zr Alloys

The partial (D¯Hi) and the integral (?H) enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys have been determined by high-temperature isoperibolic calorimetry at 1565 ± 5 K. The heat capacity (Cp) of liquid Ni26Zr74 has been measured by adiabatic calorimetry (Cp = 53.5 ± 2.2 J mol-1 K-1 at 1261 ± 15 K). The integral enthalpy of mixing changes with composition from a small positive (Cu-Ni; DH (xNi = 0.50, T = 1473 to 1750 K) = 2.9 kJ mol-1) to a moderate negative (Cu-Zr;DH(xZr = 0.46, T = 1485 K) = -16.2 kJ mol-1) and a high negative value (Ni-Zr; DH(xZr = 0.37,T = 1565 K) = -45.8 kJ mol-1). Regression analysis of new data, together with the literature data for liquid Ni-Zr alloys, results in the following relationships in kJ mol-1 (standard states: Cu (l), Ni (l), and Zr (l)):for Ni-Zr (1281 = T = 2270 K),