Temperature dependent deformation behavior and stacking fault energy of Fe40Mn40Co10Cr10 alloy

The variation in stacking fault energy (SFE) with the change in temperature has been evaluated experimentally for Fe40Mn40Co10Cr10 high entropy alloy. The distance between partial dislocations was measured using transmission electron microscopy (TEM) based weak-beam dark field (WBDF) technique. SFE of the system was found to be 37.7 (+/- 7) mJ/m(2) and 19.5 (+/- 5) mJ/m(2) at room temperature (RT) and -100 degrees C, respectively. Owing to the decrease in SFE, a transition in the deformation behavior occurred from limited twin formation and slip dominance at RT to mixed-mode consisting of FCC -> HCP transformation and twinning at -100 degrees C. Simultaneous occurrence of twins and deformation-induced martensitic transformation led to superior strength-ductility combination in the specimen deformed at -100 degrees C. SFE of the studied alloy at RT was 42% higher than that of the equiatomic FeMnCoCrNi alloy. This increase in SFE, despite removal of Ni can be understood by considering the effect of the alloy chemistry re-adjustment on Delta G(gamma ->epsilon). (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.