Theoretical Examination of Some Thermodynamic Properties in In-Bi-Sn Liquid Alloy and its Sub-binary Systems

The molecular interaction volume model was utilized to calculate the thermodynamic activity of the components in the following binary lead-free solder alloys: Bi-In at 900 K, Bi-Sn at 600 K, and In-Sn at 700 K. The theoretical values were compared with the corresponding experimental values. For the validation of the model parameters, the determination and comparison of the excess Gibbs free energy of mixing ( G M xs ) in Bi-Sn, Bi-In, and In-Sn liquid alloys were performed with the corresponding experimental data found in the literature. Significant concurrence has been noted between theoretical predictions and experimental results in binary systems. Moreover, the calculated model parameters were employed to determine the activity of indium (In) in ternary liquid alloys composed of indium, bismuth (Bi), and tin (Sn), as well as G M xs for the same ternary liquid alloys at a temperature of 813 K for all the three cross-sections, i.e., X Bi : X Sn = 1:2, 1:1, and 2:1. The arrangement between the predicted and experimental outcomes is generally satisfactory for the ternary alloys, except for the case of X Bi : X Sn = 2:1.