Enthalpy of mixing of liquid Cu-Ni-Si alloys

The pal tial and the integral enthalpies of mixing of liquid Cu-Si (T = 1281 +/- 2 K), liquid Ni-Si (T = 1575 +/- 5 K) and liquid Cu-Ni-Si (T = 1575 +/- 5 :K) alloys have been measured using a high temperature isoperibolic calorimeter. The minimum of the integral enthalpy of mixing of the ternary liquid alloys changes gradually with composition from -14.5 kJ mol(-1)(Cu-25 at.% Si) up to -67.0 kJ mol(-1) (Ni-38 at.% Si). With a view to a direct use of the thermodynamic properties, the integral enthalpy of mixing of the ternary alloys are analytically described by the thermodynamically adapted power series according to the right hand Colinet geometry using a least squares regression analysis. An association model was applied to describe the thermodynamic functions of mixing of the limiting binary and the ternary liquid Cu-Ni-Si alloys. The calculations show a good agreement with the experimental data.