Thermodynamic consideration of the effect of alloying elements on martensitic transformation in Fe-Mn-Si based alloys

The critical driving force for martensitic transformation, the stacking fault energy of parent phase at the start martensite start temperature Ms and the influence of anti-ferromagnetic transition on the Gibbs energy of Fe-Mn-Si alloys have been reviewed. The Gibbs energies of the fcc(y) and hcp(e) phases as a function of temperature have also been evaluated for Fe-Mn-Si-Cr quaternary alloys. The critical driving force for martensitic transformation in a representative quaternary alloy (Fe-26.4Mn-6.2Si-5.2Cr) was determined to be -145.25 J/mol, significantly lower than the value for Fe-30Mn-6Si, implying that the substitution of Cr for Mn decreases the stacking fault energy of the austenite.