Mechanism of grain refinement in an equiatomic medium-entropy alloy CrCoNi during hot deformation

With promising mechanical properties, the newly developed medium-entropy alloy (MEA) has aroused widespread interest recently. Plastic deformation processes including hot working are usually adopted to refine the grain of many alloys and thereby enhance the strength, hardness, and wear resistance at low temperatures. So far, few discoveries have reported the mechanism of grain refinement during hot deformation on MEA, especially for CrCoNi. In this article, plastic deformation at different conditions was intentionally designed to uncover the underlying mechanism of grain refinement in CrCoNi MEA alloy. Unlike many other alloys with low stacking fault energy, the occurrence of continuous dynamic recrystallization during hot deformation of CrCoNi alloy has been unexpectedly discovered, which is proved as the dominating mechanism for grain refinement of the current alloy.