Microstructure and Electrochemical Corrosion Behavior of Vacuum-Cladded FeNiCoCrMoBSi High-Entropy Alloy Coating

The microstructure and electrochemical corrosion performance of vacuum cladding FeNiCoCrMoBSi HEA coatings were investigated. The results show that the coating forms an FCC+σ eutectic structure. The FCC matrix phase has an abalone crystal structure. The diffraction angle of the FCC crystal plane (111) is positively correlated with the remelting temperature, while its diffraction peak intensity and grain size are inversely correlated. Unlike the coatings obtained at remelting temperatures of 1150°C and 1230°C, where the σ phase is a Mo poor phase, the coating obtained at the remelting temperature of 1190°C has a Mo-rich phase. The coating has the lowest self-corrosion current density (3.31 μA/cm²), the highest self-corrosion potential (−0.3797 V), the highest polarization impedance (69 616 Ω), and impedance modulus (23 205.68 W cm²). Its impedance modulus is 2.89 times and 2.04 times higher than those of the coatings remelted at 1150°C and 1230°C, respectively, demonstrating excellent electrochemical corrosion resistance. This can be attributed to the comprehensive effect of various factors, such as FCC+σ dual phases, dense coating structure, and excellent passivation film.