The enhanced static recrystallization kinetics of a non-equiatomic high entropy alloy through the reverse transformation of strain induced martensite

The present work deals with the static recrystallization behavior of a cold rolled non-equiatomic Fe50Mn30Co10Cr10 high entropy alloy. Towards this end, the experimented alloy was cold rolled to a total thickness reduction of 60% and was then isothermally annealed in the temperatures range of 750–850 °C for various periods of time followed by air coolling. It was found that the reverse transformation of the strain induced martensite phase during continues heating results in formation of lath-shaped reversed regions holding high density of dislocation tangles and stacking faults. During isothermal annealing, these highly stored energy regions serve as preferred nucleation sites of statically recrystallized grains. The recrystallization kinetics has been analyzed in terms of the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. Interestingly, the Avrami exponent ranged from 1.62 to 1.84 and deviates from the ideal values that was discussed considering the various capability of thermal martensite, strain induced martensite and face center cubic phase for static recrystallization. The activation energy of recrystallization is found to be much lower than that of bulk diffusion of each constituent. This is attributed to the progressive substructure development which provides the high track diffusion through the low angle boundaries.