Microstructure and Mechanical Properties of Nanocrystalline CoCrCuFeNi High-Entropy Alloy Coating Manufactured by Atmospheric Plasma Spraying

CoCrCuFeNi high-entropy alloy (HEA) coating was prepared on the surface of 316 stainless steel (SS) by atmospheric plasma spraying (APS), for the first time to our knowledge, to improve its hardness and wear resistance. The coating is composed of a single face-centered cubic phase. Due to the high in-flight particle velocity and rapid cooling rate of APS process, nanocrystalline grains with a size of about 40 nm are formed in the coating, and component segregation is not detected. Compared with the CoCrCuFeNi bulks and coatings prepared by other techniques, the APS coating in the present study exhibits a higher microhardness, 331HV_0.1. This increase in hardness is mainly attributed to the significant grain refinement. Wear resistance of the coating is 2.2 times that of 316SS. This study provides a deposition method for high-performance nanocrystalline HEA coatings with uniform composition, especially for HEAs with component segregation when prepared through other methods.