Corrosion behavior of LMD-fabricated Fe36Mn21Cr18Ni15Al10 high-entropy alloy in supercritical CO2

Fe36Mn21Cr18Ni15Al10 high-entropy alloy was fabricated by laser metal deposition (LMD), and its corrosion behavior in supercritical CO2 (S-CO2) at 500 °C and 25 MPa was investigated. The results show that a distinct layered corrosion structure was formed during exposure. An Al-rich oxide layer formed first at the oxide/substrate interface, while Cr-rich protective oxides subsequently developed and stacked, jointly providing the main corrosion resistance. With prolonged exposure, local degradation of the protective layer created outward diffusion pathways for Mn, leading to the formation of Mn-dominated oxides on the outer surface. Cross-sectional analysis further revealed the presence of a pronounced Cr/Mn-depleted zone beneath the oxide scale, whereas no obvious carburization was detected. These findings clarify the oxidation mechanism of the LMD-fabricated high-entropy alloy in S-CO2 and provide useful guidance for its potential application in advanced energy systems.