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 xCu/xNi = 3/1, 1/3 at xHf = 0–0.45 and xCu/xNi = 1/1 at xHf = 0–0.40. The limiting partial mixing enthalpies of undercooled liquid hafnium in liquid Cu–Ni alloys are (–158 ± 13) kJ mol−1 (section xCu/xNi = 3/1), (–213 ± 11) kJ mol−1 (section xCu/xNi = 1/1), and (–229 ± 11) kJ mol−1 (section xCu/xNi = 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.