Temperature dependence of corrosion behavior of a dual-phase Fe50Mn30Co10Cr10 high entropy alloy in supercritical water at 380–650 °C

Corrosion behavior of a dual-phase Fe50Mn30Co10Cr10 HEA subjected to supercritical water at different temperatures was investigated. Both weight gain and oxide film thickness increased with increasing temperatures. An outer layer with polyhedral MnFe2O4 particles and an inner layer containing a mixture of CrMn1.5O4 and Fe3O4 were formed at 380 °C. Mn2O3 outer and CrMn1.5O4 inner layers developed at 550 and 650 °C, but the loose granular Mn2O3 particles at 550 °C transformed into a compact oxide film at 650 °C. Besides, Cr2O3 oxide particles were observed along the grain boundaries. The corrosion mechanism at different temperatures was also discussed. •Corrosion behavior of dual-phase Fe50Mn30Co10Cr10 HEA in supercritical water at different temperatures was investigated.•Mn element determined the structure of the oxide film and the corrosion kinetics of HEA.•A duplex-layer oxide film developed on HEA at all exposure temperatures, while chemical composition varied.•Cr2O3 oxide particles were observed along the grain boundaries due to the inward diffusion of oxygen.