Investigation on the microstructure, wear and corrosion resistance of FeCoNiCrMox high-entropy alloy coatings deposited on 40Cr by laser cladding.

Many engineering structural parts, such as internal gear pumps, worked in high-salt and high-temperature environments. The material (40Cr) of the parts in the pump failed due to severe wear and corrosion. To improve the wear resistance and corrosion resistance of 40Cr, the FeCoNiCrMo_x (x = 0, 0.3, 0.6, 0.9, 1.2) HEAs coatings were deposited on the surface of 40Cr by laser cladding technology, and the phase structure, microstructure and hardness of the coatings were investigated. In addition, friction and wear tests, electrochemical tests and neutral salt spray tests were conducted to investigate the effect of Mo content on the wear resistance and corrosion resistance of the coatings. The results showed that the phase structure of the FeCoNiCrMo₀ coating was the FCC phase, and the phase of the FeCoNiCrMo_x (x = 0.3, 0.6, 0.9, 1.2) coatings were composed of the FCC phase and σ phase. The Mo element was enriched in interdendrite. With the increasing content of Mo elements, solid solution strengthening, fine grain strengthening, and second phase strengthening occurred in the coatings, which led to the increased hardness and wear resistance of the coatings. The FeCoNiCrMo_1.2 coating had the best wear resistance. In the 3.5%NaCl solution, the corrosion resistance of the coatings was better than that of the substrate. With the increase of Mo content, the corrosion potential of the coatings drifted positively, the corrosion current density decreased, and the corrosion resistance increased. However, with excessive Mo element content, the σ phase will precipitate, leading to galvanic coupling corrosion of the coatings and reducing the corrosion resistance. Because the FeCoNiCrMo_0.9 coating had the highest corrosion potential and the lowest corrosion current density. Therefore, it had the best corrosion resistance. The neutral salt spray test result also showed that the corrosion resistance of the FeCoNiCrMo_0.9 coating was the best. [ABSTRACT FROM AUTHOR]