Emf Measurements in the Liquid Au-Cu-Sn Lead-free Solder Alloys

An emf method was employed to determine tin activities in the liquid Au-Cu-Sn alloys using solid electrolyte galvanic cells. The whole concentration range of the Gibbs triangle was covered, and emf readings were taken for both heating and cooling mode within temperature interval: 900-1360 K. Emf versus T relations were approximated by line equations, and its coefficients were listed in tables. Tin activity versus composition curves were constructed, displaying negative deviation from ideal behavior. Activity data were compared to the respective values calculated from COST 531 database using binary formalism, and relatively good agreement was observed.