Quantification of ε-martensite in Fe–17Mn alloy

The volume fraction of ε-martensite in a Fe-17Mn alloy was quantitatively analyzed by XRD and EBSD under different surface preparation conditions. Mechanical polishing induced martensite transformation, leading to an apparent ε-martensite fraction of about 96%. After electrolytic polishing, the surface layer was removed, yielding a reliable ε-martensite fraction of approximately 72%. The quantitative phase fraction obtained from EBSD shows a pronounced dependence on the step size. As the step size decreased, the volume fraction of ε-martensite gradually increased, however, the EBSD results consistently remained lower than the XRD values, owing to the ε-martensite embryos. This study highlights the methodology for quantification and microstructural characterization of the complex γ/ε dual-phase in fcc high-Mn alloys and high-entropy alloys with low stacking fault energy.