Application of molecular interaction volume model for predicting the Ca activity coefficients in SiCa binary and SiCaPb ternary alloys

•MIVM was reliable for predicting the activity coefficients of Ca in SiCa binary and SiCaPb ternary alloys.•Kuo-chih Chou's method was feasible to obtain the activities of Si, Pb in SiPb binary alloy and Ca, Pb in CaPb binary alloy.•The predicted results were in good agreement with the experimental data.

In this paper, the activity coefficients of calcium in SiCa binary and SiCaPb ternary alloys were each calculated by the molecular interaction volume model (MIVM). The value of the infinite dilution activity coefficient of calcium was determined to be 0.000863 in the SiCa binary alloy at 1723 K. The activities of silicon and lead in the SiPb binary alloy and of calcium and lead in the CaPb binary alloy were calculated by the Kuo-chih Chou's method using phase diagrams, whose effectiveness was verified. In comparison with the experimental data, all errors predicted by the MIVM were between ±0.22 to ±29.7% and the standard deviations were between ±2.26 × 10−7 to ±0.073. Such predicted values are actually small and in good agreement with the experimental data, which indicates that the MIVM is reliable to predict the activities or activity coefficients of SiCa binary and SiCaPb ternary alloys.