Study on structure and corrosion behavior of FeCoCrNiMo high-entropy alloy coatings prepared by mechanical alloying and plasma spraying

To overcome the problem of element segregation in high entropy alloys and prepare uniform high entropy alloy coatings, FeCoCrNiMox composite powders were prepared by mechanical alloying technique, and it was prepared into high entropy alloy coatings with FCC phase by plasma spraying. The microstructure and phase composition of the coating were characterized by SEM, TEM, and X-ray diffraction. The coating’s hardness, elastic modulus, and fracture toughness were tested and the corrosion resistance was analyzed in simulated seawater. The results show that the hardness of the coating is 606.15 HV, the modulus of elasticity is 128.42 GPa and the fracture toughness is 43.98 MPa•m1/2. The corrosion potential of the coating in 3.5 wt.% NaCl solution is -0.49 V and the corrosion current density is 1.2×10-6A/〖cm〗^2. The electrochemical system consists of three parts: electrolyte, adsorption film and metallic oxide film produced during immerse, and FeCoNiCrMo high-entropy alloy coating. Over increasingly long periods, the corrosion reaction rate increases first and then decreases, the corrosion product film composed of metal oxides reaches a dynamic balance between formation and dissolution, and the internal reaction of the coating slows down.