Calorimetric studies of Cu–Li, Li–Sn, and Cu–Li–Sn

Integral molar enthalpies of mixing were determined by drop calorimetry for Cu–Li–Sn at 1073 K along five sections x(Cu)/x(Sn) ≈ 1:1, x(Cu)/x(Sn) ≈ 2:3, x(Cu)/x(Sn) ≈ 1:4, x(Li)/x(Sn) ≈ 1:1, and x(Li)/x(Sn) ≈ 1:4. The integral and partial molar mixing enthalpies of Cu–Li and Li–Sn were measured at the same temperature, for Li–Sn in addition at 773 K. All binary data could be described by Redlich–Kister-polynomials. Cu–Li shows an endothermic mixing effect with a maximum in the integral molar mixing enthalpy of ∼5300 J · mol(−1) at x(Cu) = 0.5, Li–Sn an exothermic minimum of ∼ −37,000 J · mol(−1) at x(Sn) ∼ 0.2. For Li–Sn no significant temperature dependence between 773 K and 1073 K could be deduced. Our measured ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Chou is given.