Analytical evaluation of component activity of Ca-Si-Al system

The excess partial molar Gibbs energy of Ca in the CaSiAl ternary system was expressed as a polynome, then the coefficients A_jk involved in the polynome were determined mainly based on the boundary data of the ternary alloy with the least-square method. The coefficients F_jk contained in the polynomial of excess molar Gibbs energy of the alloy were determined in the light of Gibbs-Duhem Equation. The polynomial expression of the excess partial molar Gibbs energy of Si and Al, in which the known A_jk and F_jk were involved, was derived according to the modified I-D means. All of the evaluated component activities of the alloy are available in the whole composition range. The results show a good agreement with the experimental data.