Thermodynamic activity in Zn–Cu–Sn–In liquid solder alloys: a comprehensive analysis using the molecular interaction volume model.

The molecular interaction volume model (MIVM) was employed to estimate the activity of each component in Zinc–Copper–Tin–Indium (Zn–Cu–Sn–In) quaternary liquid alloys at 1023 K, keeping indium content constant, i.e. x_In = 0.1, and varying molar ratios of Cu and Sn (x_Cu/x_Sn). Furthermore, the model has been used to determine the activity of each component of all sub-binary systems, namely Cu–Zn at 1200 K, Sn–Zn at 750 K, In–Zn at 700 K, Cu–Sn at 1400 K, Cu–In at 1073 K, In–Sn at 700 K, and Zn–Cu–In liquid ternary alloys at 1023 K for three molar ratios of Cu and In, i.e. x_Cu/x_In = 1:2, 1:1, and 2:1. We found that the activity deviations of Zn from Raoult's law transform from positive to negative as the x_Cu/x_In ratio changes from 1:2 to 2:1. The estimated values were analyzed with the correspondent experimental results in the case of ternary and all the binary liquid alloys. There is a notable agreement observed between theoretical forecasts and practical findings in both binary and ternary systems. This work provides a thorough thermodynamic study of the Zn, Cu, Sn, and In quaternary systems. [ABSTRACT FROM AUTHOR]