Stability of Cr oxide formed on Fe-20Cr-2Si alloy in 1200 degrees C steam or oxygen

Abstract

Fe-20Cr-2Si alloy, proposed as a high-temperature oxidation barrier for accident-tolerant fuel cladding in light water reactors, maintained oxidation resistance at 1200 degrees C under Ar-50%H2O and Ar-20%O2 environments for up to 24 h. However, Cr2O3 on the Fe-20Cr-2Si alloy volatilized above 1000 degrees C, degradation started under Ar20%O2, and voids were observed at the metal/oxide interface. These were attributed to the copious formation of volatile species owing to the high oxygen partial pressure in Ar-20%O2. Thus, more vacancies were generated and moved to the metal/oxide interface. Contrastingly, degradation was not initiated under Ar-50%H2O, indicating sufficient resistance of Fe-20Cr-2Si to highly oxidizing environments.