Thermodynamic Assessment of the Fe–Mn Binary Alloy System using the CALPHAD Method

Abstract

Thermodynamic assessment of and predictions for the metastable binary iron−manganese alloy (Fe−Mn system) have been undertaken using the CALPHAD (calculation of phase diagram) method. Phase diagrams, Gibbs energies of mixing, excess Gibbs energies, thermodynamic molar activities, coefficient of activities, and partial and integral values of enthalpy have been calculated at three elevated temperatures: 1200, 1225 and 1250 K. The alloy shows positive deviations from Vegard’s and Henry’s laws (the latter deviation being small) and corresponding negative deviation from Raoult’s law (ideal Gibbs curve). Results show that the ferromagnetic state of the Fe−Mn alloy is the most stable. Phase equilibria show almost ideal characteristic behaviour. Overall the alloy is at equilibrium and has good stability.