Effect of Mo Content on the Microstructure and Properties of FeCoCrNiMox High-Entropy Alloy Coatings Prepared by High-Velocity Oxy-Fuel Spraying

Abstract

High-entropy alloy coatings (HEA) were applied to key components such as cutting tools, molds, and valves. In this research, FeCoCrNiMox high-entropy alloy coatings were deposited on 45 steel substrates using high-velocity oxy-fuel (HVOF) spraying. The influence of molybdenum (Mo) content on the coating properties was systematically investigated by characterizing the microstructure of the coating surfaces and cross-sections, as well as by evaluating the hardness, and wear resistance. The coating thickness ranges from 75 – 150 µm. During the spraying process, some powder particles with high Mo content have remained incompletely melted, leading to their embedding in the coating in a solid state. By adding Mo element, the coatings hardness reached 750 – 800 HV0.3, more than twice higher than that of the steel substrate. The increased Mo content potentially enhances the solid solution strengthening effect within the high-entropy alloy system, thereby suppressing segregation tendencies of elements such as Fe and consequently improving overall coating homogeneity.