Enthalpy of mixing in the quaternary (Al, Ga, Sn, Zn) system: calorimetry measurements and Redlich-Kister modelling

The enthalpy of mixing of the (Ga, Sn, Zn) liquid phase has been explored at 715 K by Calvet drop calorimetry. Following the three isopletic cuts x_i = x_j we have determined the ternary term of a fifth order Redlich-Kister model. An exploration of the quaternary (Al, Ga, Sn, Zn) system along the two isoplethic cuts x_Ga = x_Sn = x_Zn and x_Al = x_Ga = x_Zn has been realized too. A Redlich-Kister polynom established for this quaternary system was extrapolated up to the ternary (Al, Sn, Zn) border system which remains inaccessible to calorimetry with an open crucible. A Darken quadratic model based on a statistical Bragg-Williams description of the (Al, Sn, Zn) liquid phase is compared to this calorimetry extrapolation.