Impressive high-temperature oxidation resistance of FeCrNiMnAl high entropy alloy coating on the ferritic/martensitic steel with primordial Al₂O₃ and Mn₃O₄ gradient films

Recently, ferritic/martensitic steel (F/M) has been widely used in the fields of thermal power unit and nuclear energy. While the disadvantage of insufficient oxidation resistance at high temperature limits the further application of F/M. Therefore, it is very necessary to develop an effective method to improve its performance. Up to now, FeCrNi-based high entropy alloy was widely used as the protective coating on F/M. However, there are few researches on the high-temperature antioxidant property of FeCrNiMnAl coating on F/M, and its microstructure evolution behavior in high-temperature environment has not been reported. Herein, this work prepared FeCrNiMnAl coating on F/M with high binding force and dimensional stability by laser cladding. Importantly, the evolution behavior of high temperature oxidation of FeCrNiMnAl coating was first reported. The results showed that the Young's modulus, indentation hardness, micro-hardness and friction coefficient of FeCrNiMnAl coating reached to 294.5 GPa, 16.9 GPa, 510 HV, and 0.341, respectively. The average oxidation rates during 200 h at 550 ℃ of F/M (2.78 ×10⁻³ mg/(cm²·h)) and FeCrNiMnAl coating (1.07 ×10⁻³ mg/(cm²·h)) exhibited that the oxidation resistance of F/M was greatly improved. It was pointed out that the impressive oxidation resistance of the coating was attributed to the formation of Al₂O₃ and Mn₃O₄ gradient films. This work provides a promising insight to deeply understand the high temperature evolution behavior of FeCrNiMnAl coating.