Coupling Binary and Ternary Information in Assessing the Fcc/Hcp Relative Phase Stability and Martensitic Transformation in Fe-Mn-Co and Fe-Mn-Si Alloys

Abstract
This paper presents a study of the composition dependence of the fcc/hcp martensitic transformation temperatures and relative phase stability of these structures in Fe-Mn-Co and Fe-Mn-Si alloys. The approach combines new experimental determinations of M_s and A_s in the binary systems Fe-Mn and Fe-Co, and in both ternary systems with a critical analysis of the previously published experimental data, and thermodynamic calculations. It is shown how this combination of binary and ternary information with various methods of analysis can be used to establish the T₀-temperatures in the Fe-Mn-Co system and to refine the thermodynamic description of the metastable hcp structure of the Fe-Co system. The present methods also help to detect possible inconsistencies in the previously reported M_s and A_s data for Fe-Mn-Si alloys, which is used as a basis for discussing the most recent calculation of M_s temperatures in this system.