Abstract
Activity of tin in liquid Sn-Bi-Sb was derived by EMF measurement of galvanic cell with fused salts electrolyte in the temperature range of 700 to 1000K in the whole composition range. Activity of tin at 900K shows very small positive deviation from Raoult's law for Sn-Bi alloys and moderately negative deviation for Sn-Sb alloys. Activity of ternary alloys along SbyBi(1-y)-Sn (y=0.25, 0.50 and 0.75) shows negative deviation and the deviation becomes large with increasing Sb content. Excess free energy of mixing is derived using Darken's method for Gibbs-Duhem equation and the values are compared with those by model calculations based on the three constitutive binary data.
