Effect of carbon on recrystallization and grain growth behavior of carbide-free FeMnCoNiCx high-entropy alloys

The impact of interstitial carbon on recrystallization behavior was investigated in designed carbide-free FeMnCoNiC x high-entropy alloys (HEAs) by utilizing weak carbide-forming elements. The results indicate that recrystallization and grain growth are both effectively facilitated in carbon-containing high-entropy alloys. Under identical cold rolling conditions, carbon-containing HEAs exhibit higher dislocation density and deformation stored energy, which facilitates the recrystallization behavior. Meanwhile, the activation energy for grain growth in carbon-containing alloys is lower than that in carbon-free alloys. Diffusion couple experiments reveal that the addition of carbon increases the diffusion coefficients of metallic elements, thereby reducing the activation energy for grain growth and consequently accelerating grain coarsening. This phenomenon stands in sharp contrast to the conventional understanding, in which carbon suppresses recrystallization by forming carbide secondary phases that pin grain boundaries.