Calorimetric investigation of the mixing enthalpy of liquid Co-Cu-Ti alloys at 1873 K

The mixing enthalpies of liquid Co-Cu-Ti alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along sections x(Co)/x(Cu) = 3/1, 1/3 at x(Ti) = 0 - 0.62 and along section x(Co)/x(Cu) = 1/1 at x(Ti) = 0 - 0.54. The limiting partial enthalpies of mixing of undercooled liquid titanium in liquid Co-Cu alloys, Delta H-Ti(infinity), are (-128 +/- 21) kJ mol(-1) (section x(Co)/x(Cu) = 3/1), (-130 +/- 12) kJ mol(-1) (section x(Co)/x(Cu) = 1/1) and (-107 +/- 11) kJ mol(-1) (section x(Co)/x(Cu) = 1/3). The integral mixing enthalpies are predominantly negative in the investigated composition range. For the integral mixing enthalpy, an analytical expression was obtained by the least square fit of the experimental results using the Redlich-Kister-Muggianu polynomial.