A novel high-entropy alloy composite coating with core-shell structures prepared by plasma cladding

A novel Ti(C,N)-reinforced body-centered cubic (BCC)-based Cr20Cu20Fe20Ni20Al20 high-entropy alloy (HEA) composite coating was prepared by a synchronized powder feeding plasma transferred arc (PTA) cladding. Microstructures and the wear properties of the HEA composite coating were investigated. Results showed that the HEA composite coating that exhibited dense microstructures and good metallurgical bonding with the substrate was mainly composed of BCC matrix grains containing intragranular ordered BCC (B2) cuboidal nanoprecipitates and face-centered cubic (FCC) micro/nano Ti(C,N) particles distributed along the grain boundaries. Both the Ti(C,N) particles and the cuboidal nanoprecipitates exhibited core-shell structures with the characteristics of high toughness in the core and high strength in the shell, which led to the combination of the high strength and toughness for the HEA composite coating favoring the improvement of wear resistance. The microhardness of the HEA composite coating was 3.33 times greater than that of the Q235 substrate and 127.4 HV0.1 higher than that of the pure Cr20Cu20Fe20Ni20Al20 HEA coating. The wear resistance of the HEA composite coating increased 3.03 times and 8.06 times compared with that of the pure HEA coating and substrate, respectively. The main wear mechanism of the HEA composite coating was mild abrasive wear.