Thermodynamics of lead-free Sn-Au-Sb liquid alloys: a theoretical approach

The activities of the constituent metals in binary liquid solder alloys, namely Sb-Sn at 905 K, Au-Sn at 823 K, and Au-Sb at 913 K, and the activities of Sn in the ternary liquid solder alloys Sn-Au-Sb at 873 K for three cross-sections, i.e. for three different ratios of gold to antimony (xAu: xSb) = 2: 1, 1: 1, and 1: 2, have been computed using the molecular interaction volume model (MIVM). The predicted values and the associated experimental data were analyzed. In addition, the excess Gibbs free energy of mixing (GMxs) of the binary alloys Sb-Sn, Au-Sn, and Au-Sb and of the ternary alloys Sn-Au-Sb for all three cross-sections was also calculated using the same model and analyzed with the relevant experimental values accessible in the articles to determine the sustainability of the model parameters. The agreement between the theoretical and experimental results has been found to be satisfactory for both the binary and ternary systems.