Mixing enthalpy of liquid Cu-Hf-Ni alloys at 1873 K

The mixing enthalpies of liquid Cu-Hf-Ni alloys were determined at 1873 K by applying a high-temperature isoperibolic calorimeter. The investigation was performed along the sections x (Cu)/x (Ni) = 3/1, 1/3 at x (Hf) = 0-0.45 and x (Cu)/x (Ni) = 1/1 at x (Hf) = 0-0.40. The limiting partial mixing enthalpies of undercooled liquid hafnium in liquid Cu-Ni alloys are (-158 +/- 13) kJ mol(-1) (section x (Cu)/x (Ni) = 3/1), (-213 +/- 11) kJ mol(-1) (section x (Cu)/x (Ni) = 1/1), and (-229 +/- 11) kJ mol(-1) (section x (Cu)/x (Ni) = 1/3). The integral mixing enthalpies are negative in a wide composition range. The Redlich-Kister-Muggianu polynomial was used for the least square fit of the experimental results to obtain an analytical expression for the integral mixing enthalpy.