Oxidation behavior and microstructure evolution of alumina-forming austenitic & high entropy alloys in steam environment at 1200 °C

Abstract Oxidation tests of alumina-forming austenitic (AFA) alloys and high entropy alloys (HEA) have been performed in steam at 1200 °C. AFA alloys with composition formula Fe-3Al-16Cr-(19-21)Ni (wt.%) and HEA with formula Al(7.9-8.9)Cr(21.4-23.2)Ni(34.3-35)Febal (at.%) show low oxidation rate due to the formation of α-Al2O3 scale. By adding yttrium to AFA or niobium to HEA, the samples show no evidence of scale exfoliation. HEA with titanium addition forms a thick oxide layer based on TiO2, Cr2O3 and internal Al oxidation. The growth of oxide scale is discussed based on the oxygen partial pressure of metal oxides and dissociation oxygen pressure of the steam.