Tuning mechanical metastability in FeMnCo medium entropy alloys and a peek into deformable hexagonal close-packed martensite

Abstract

We report here the compositional dependency of face-centered cubic (FCC) to hexagonal close-packed (HCP) martensitic transformation in FeMnCo medium entropy alloys (MEAs) and insights into the underlying transformation mechanisms. To this end, we designed MEAs with the same Fe-to-Mn ratio and explored the phase stability therein. Higher Co content was found to facilitate the FCC-HCP transformation kinetics. In situ electron backscatter diffraction studies underpinned an FCC-HCP-(new)FCC transformation chain and its underlying atomistic mechanisms were directly explored via aberration-corrected scanning transmission electron microscopy.