Effects of N addition on microstructure and mechanical properties of CoCrFeNiMn high entropy alloy produced by mechanical alloying and vacuum hot pressing sintering

Most of multi-component high entropy alloys (HEAs) are only based on metal elements and rarely added with nonmetallic elements. In present paper, CoCrFeNiMn HEA added with 0.1 at.% N has been successfully synthesized by mechanical alloying (MA) followed by vacuum hot pressing sintering (VHPS). During the MA process, the alloying elements were gradually alloyed and formed as face-center (FCC) solid solutions. Subsequently, σ phases, Cr2N phases, FCC matrix phases with traces of Cr23C6 carbides were observed after VHPS. In comparison with CoCrFeNiMn HEA produced by the same method, the Vickers hardness increased up to 468HV, while the yield stress, ultimate compressive strength increased by 203 MPa and 115 MPa respectively, accompanied by a small decrease in plasticity. This demonstrates that adding N element is a viable approach for properties enhancement of HEAs.