Effect of Deformation and Annealing Treatment on Microstructure Evolution of Fe47Mn3oCo10Cr10B3 Dual-Phase High-Entropy Alloy

In recent years, non-equiatomic high-entropy alloy (HEA) has been proposed to explore the flexibility of its design rule, avoiding the strength-ductility tradeoff. For further progress, non-equiatomic HEAs doped with interstitial atoms are developed. Boron, an effective dopant in metallurgy, has been used due to the beneficial compositional effects on the interfaces of metallic materials. In this work, the effects of deformation and annealing treatments on the microstructural evolution of Fe47Mn30Co10Cr10B3 dual-phase HEAs were investigated via electron channeling contrast imaging (ECCI) and EBSD. The results show that there are three stages in the deformation mechanism with an increase in the deformation degree, which include the dominant dislocation slip in the fcc phase, joint deformation of the transformation-induced plasticity and dislocation slip, and activation of dislocation slip in the hcp phase. With an increase in the annealing holding time, the partial recrystallization transformed to complete recrystallization. Further, particles located in the grain boundary can effectively restrain grain growth, and in turn, exhibit the bimodal grain size. The amount of annealing twinning variants is influenced by the fcc grain orientation: grains with < 101 > orientation are prone to forming multiple twinning variants, whereas, grains with < 111 > and < 100 > orientations are prone to forming a single twinning variant. The amount of annealing twinning variants also affected the morphological characteristics of the single hcp variant; the absence of annealing twinning variant is ascribed to the formation of blocky hcp phases and the single annealing twinning variant is attributed to the formation of laminate hcp phase. Moreover, the number of hcp variants was affected by the fcc grain sizes; large-sized grains facilitated the formation of multiple hcp variants, whereas, small-sized grains facilitated the formation of the single hcp variant.