New studies on wear and corrosion behavior of laser cladding FeNiCoCrMox high entropy alloy coating: The role of Mo

In this paper, the wear and corrosion resistance of FeNiCoCrMox (x: atomic ratio, x = 0, 0.15, 0.20, 0.25) high entropy alloy coatings (HEACs) which prepared by laser cladding (LC) technology on 316 stainless steel (SS) was investigated. According to XRD, SEM, MicroXAM-3D, microhardness tester and electrochemical workstation tests results, the HEACs presented typical DR-ID structure with single FCC solid solution phase. The average microhardness of Mo0, Mo0.15, Mo0.20 and Mo0.25 HEACs increased by 70.1%, 77.0%, 84.9% and 90.5% relative to the substrate. Dry sliding friction and wear tests results showed that the average friction coefficient of the HEACs were significantly lower than that of 316 SS substrate. Meanwhile, it can be found that Mo0.25 HEACs had the lowest average friction coefficient which displayed the best wear resistance. Compared with Mo0 HEAC, the specific wear rates of Mo0.15, Mo0.20 and Mo0.25 HEACs decreased by 11.1%, 27.8% and 38.9% respectively. The electrochemical tests results showed that the corrosion type of HEACs was intergranular corrosion and all HEACs had a higher corrosion resistance than that of 304 SS or 316 SS. Moreover, Mo0.20 HEACs showed the best corrosion resistance due to the enhancing effect of MoO3 on Cr2O3 passivation film.