Thermodynamic description of the ternary Pd–Sn–Zn system

Abstract

Abstract The thermodynamic properties of the liquid Pd–Sn–Zn ternary system were investigated, because the Sn–Zn alloy is a promising lead-free solder and Pd can be used as a substrate material. Using an appropriate galvanic cell, the partial free energies of Zn in liquid Pd–Sn–Zn alloys were determined as a function of concentration and temperature. Thermodynamic properties were obtained for 18 alloys. Their composition was situated on two cross-sections with the constant molar ratios of Pd: Sn = 1:3 and 1:9. The integral Gibbs free energy and the integral enthalpy for the ternary system at 1000 K were calculated by Gibbs–Duhem integration. For the liquid binary Pd–Sn system, some inconsistencies were found in previous CALPHAD results. Considering the latest experimental information, the interaction parameters of the liquid phase were reevaluated. The liquidus temperatures were also determined from EMF measurements.