The role of anti-ferromagnetism on gamma-epsilon transformation in Fe-Mn alloys

The Fe-Mn system has been used to demonstrate the key role of anti-ferromag netic contributions to the martensitic transformation behaviour and the sta cking fault energy of fee Fe-Mn alloys. An analysis of previous work leads to the conclusion that the optimum magnetic characterisation in the low tem perature region may differ substantially from the behaviour deduced from a high temperature analysis. An alternative model has been developed, which l eads to the satisfactory quantitative prediction of the relevant M-s, A(s) and T-0 temperatures as well as stacking fault energies and the model is ca pable of being extended to ternary systems. The results also have a bearing on current expressions for the phase stability of the gamma-epsilon transf ormation in pure iron.