Driving force for γ→ε martensitic transformation and stacking fault energy of γ in Fe-Mn binary system

A regular solution model for the difference of the chemical free energy between gamma and epsilon phases during gamma --> epsilon martensitic transformation in the Fe-Mn binary system has been reexamined and partly modified based on many articles concerning the M-s and A(s) temperatures of Fe-Mn alloys. Using the regular solution model, the measured M-s temperatures, and a thermodynamic model for the stacking fault energy (SFE) of austenite (gamma), the driving force for gamma --> epsilon martensitic transformation, and the SFE of gamma have been calculated. The driving force for gamma --> epsilon martensitic transformation increases linearly from -68 to -120 J/mole with increasing Mn content from 16 to 24 wt pct. The SFE of gamma decreases to approximately 13 at. pct Mn and then increases with increasing Mn content, which is in better agreement with Schumann's result rather than Volosevich et al.'s result.