Effect of Al content on steam oxidation behavior for ferritic Fe-21Cr-xAl alloys

Abstract

Given the focus on developing novel accident-tolerant materials for nuclear fuel cladding applications, FeCrAl alloys have been considered as one of the promising candidates. To optimize the composition of FeCrAl alloys, systematic studies are necessary to understand the elemental effect on oxidation behavior at normal and accident conditions. This work focuses on understanding how the presence of 3 wt.% and 8 wt.% Al in a Fe-21Cr alloy affects their steam oxidation mechanisms and oxide architecture in the steam environment at 400 °C and 1200 °C. Results show that increasing Al content has a beneficial effect on the oxidation resistance at both temperatures. At lower temperatures, the presence of Al promotes the formation of Cr2O3 and limits Fe oxidation resulting in the formation of thinner oxides with dual uniform layers rich in Cr2O3 on the outside and rich in Al2O3 on the inside. At 1200 °C, increasing Al content from 3 to 8 % reduces transient Fe and Cr oxidation and promotes a thinner protective α-Al2O3 oxide.