Thermodynamic analysis of the Sn-Ag-Bi ternary phase diagram

Abstract

The present study was undertaken to examine the phase equilibria in the Sn-Ag-Bi ternary system, a promising candidate for use as a Pb-free solder. A regular solution approximation as well as the sublattice model was applied to describe the Gibbs energy for the individual phases. Thermodynamic parameters were achieved by combining the experimental results obtained by differential scanning calorimetry and energy dispersive X-ray microanalysis in the present study with data from the literatures. The calculation of phase diagrams showed that there are three invariant reactions in the liquidus surface of the ternary system and that the ternary eutectic point falls at 0.5%Ag, 53.9%Bi and 139°C.