Microstructure and mechanical properties of SiC whisker reinforced CoCrNi medium entropy alloys

Abstract The CoCrNi/SiC whisker (SiCw) composite was developed by a combination method of coating and spark plasma sintering (SPS). SiCw could be evenly distributed on the CoCrNi gas-atomized powder after coating and an obvious grain refinement could be observed in the microstructure of composite after sintering. Meanwhile, the CoCrNi/SiCw composite with a trace of in-situ M23C6 phases showed superior mechanical properties: addition of 2 wt% SiCw led to an increase in the yield strength (YS) and hardness from 352 MPa and 159 HV to 595 MPa and 422 HV respectively, compared with the CoCrNi MEA. The improved strength is attributed to synergistic effects of Orowan strengthening, grain refinement and thermal mismatch mechanism.