In-situ assembly from graphene encapsulated CoCrFeMnNi high-entropy alloy nanoparticles for improvement corrosion resistance and mechanical properties in metal matrix composites

Herein, graphene encapsulated equiatomic CoCrFeMnNi high-entropy alloy (Gr/FMH) micro/nanoparticles were designed and prepared by in-situ mechanical exfoliation graphite crystal. Based on the XRD, XPS, and TEM results, the graphene was robustly bonded with the substrate by Cr₇C₃. The Gr/FMH micro/nanoparticles then were used as building blocks for fabricating bulk Gr/FMH composites. The hardness and wear resistance of the bulk Gr/FMH composites were much higher than that of the FMH, The compressive yield strength of the Gr/FMH increased from 920 to 1350 MPa comparing with the FMH at room temperature, accompanied by a slight decrease in ductility. The strengthening mechanisms were grain boundary strengthening and precipitation strengthening. Moreover, due to its protective property of the homogeneously dispersed graphene on the FMH particles, the corrosion resistance of the as-prepared Gr/FMH particles was significantly improved in 0.1 M H₂SO₄ solution compared with the FMH particles. The present results shed light on extending applications of the HEA matrix composite to a broader range by incorporating graphene.