Experimental investigation and thermodynamic prediction of the Au–Cu–Sb phase diagram

Phase diagram of the ternary Au–Cu–Sb system was investigated experimentally by DTA and SEM–EDS methods and analytically by CALPHAD method. The liquids projection, invariant equilibrium, several vertical sections and isothermal section at 300 °C were predicted using COST 531 thermodynamic database. Phase transition temperatures of alloys along four predicted vertical sections of the Au–Cu–Sb ternary system with molar ratios Au:Cu = 1, Cu:Sb = 1, Au:Sb = 1 and x(Au) = 0.2 were measured by DTA (differential thermal analysis). Predicted isothermal section at 300 °C was compared with the results of the SEM (scanning electron microscope) with EDS (energy dispersive spectrometry) analysis from this work. This Au–Cu–Sb system belongs to the group of gold alloys, as potential candidates for new lead-free solder materials.

► This ternary Au–Cu–Sb system was not investigated before, its potential candidates for new lead-free solder materials in electronic devices. ► Diagram was defined using optimized literature data for thermodynamic parameters. ► Calculated values of the phase transformation temperatures are verified by the experiment. ► A good agreement is obtained for calculated and experimentally determined phase.