Lead-free solder materials: Experimental enthalpies of mixing in the Ag-Cu-Sn and Cu-Ni-Sn ternary systems

The partial and integral enthalpies of mixing of molten, ternary Ag-Cu-Sn alloys were determined at 500, 700 and 900 °C using a Calvet-type microcalorimeter. Five sections in a compositional range from pure Sn to about 40 at.% Sn were investigated. The data were fitted using a Redlich-Kister- Muggiano polynomial, where the binary interaction parameters were taken from the literature. Additionally, the temperature dependence of the ternary interaction parameters was described analytically by a linear function. In the ternary Cu-Ni-Sn system, the enthalpies of mixing were determined at 1250 °C in five sections, starting from pure Sn to about 40 at.% Sn. Again, the ternary interaction parameters were fitted using the substitutional Redlich-Kister- Muggiano model. For both ternary systems and all mentioned temperatures, isoenthalpy curves were constructed for the integral molar enthalpy of mixing.