Super capacity of boron on the grain refinement of FeCoCrNiMn high entropy alloy

Grain refinement is the effective path to simultaneous enhancing both strength and toughness of the metal materials. Here we reported that, a super grain refinement effect has been acquired in the as-cast FeCoCrNiMn high entropy alloy via adding into 0.19 wt% B. The grain size distribution has been mainly concentrated below 150 µm and the average grain size has been refined from 3903 µm to 80 µm after B adding. The electron microscopy characterizations and relevant model calculations indicates that the B can form Cr2B phase which can be used as a high-efficiency nucleating agent and significantly refine the grain of the high entropy alloy. Meanwhile, the orientation relationships between the Cr2B phase and the HEA matrix have been confirmed.