Calculation of activity coefficient from immiscible binary alloy phase diagram by means of modified sub-regular solution model

摘要

The modified sub-regular solution model was used for a calculation of the activity coefficient of im- miscible binary alloy systems. The parameters needed for the calculation are the interaction parameters, λ1 and λ2, which are represented as a linear function of temperature. T. The molar excess Gibbs free energy, G~E _m, can be written in the form G~E _m=x_A x_B[(λ_11+λ_12 T)+( λ_21+λ_22 T)x_B] The calculation is carried out numerically for three immiscible binary alloy systems, Al-Pb, Cu-TI and In-V. The agreement between the calculated and experimentally determined values of activity coefficient is excellent.