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

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 underlying mechanisms. To this end, we designed MEAs with same Fe-to-Mn ratio explored phase stability therein. Higher Co content was found facilitate FCC-HCP kinetics. In situ electron backscatter diffraction studies underpinned an FCC-HCP-(new)FCC chain its atomistic mechanisms were directly via aberration-corrected scanning transmission microscopy.