Experimental investigation and thermodynamic assessment of phase equilibria in the Ag-Au-Sn system

The phase equilibria of the Ag-Au-Sn ternary system at 300°C, 400°C, and 500°C were experimentally investigated. The equilibrium compositions of the equilibrated alloys and diffusion couples between Ag _x Au _1-x (x = 0.25, 0.75) alloys and liquid Sn were determined by electron probe microanalysis (EPMA). The phase transformations were investigated by means of differential scanning calorimetry (DSC). Based on the experimental data of phase equilibria and thermodynamic properties, the thermodynamic assessment of the Ag-Au-Sn system was carried out based on the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the Gibbs free energies of the phases were optimized, and reasonable agreement between the calculations and experimental data was obtained.