Effect of aging and α’ segregation on oxidation and electrochemical behavior of FeCrAl alloys

Abstract

FeCrAl alloys are promising candidates for next generation nuclear fuel cladding applications due to their high resistance to hydrothermal corrosion, high temperature steam oxidation, fretting, and creep properties. However, a potential area of concern for FeCrAl alloys is the precipitation of Cr-enriched α’ phase which could have an implication on the mechanical, oxidative degradation as well as electrochemical behavior. Studies in this area are limited since most of the past applications of FeCrAl alloys have been in high temperatures above the miscibility gap. In this work, we investigate the high temperature oxidation and electrochemical behavior of a modified APMT (Fe21Cr5Al3Mo) alloy in unaged condition in comparison with a thermally aged condition having α’ phase segregation. The α’ is shown to have no major role in steam oxidation resistance of FeCrAl alloys. The electrochemical behavior in chloride environments shows that the presence of α’ slightly reduces the pitting potential but shows an overall increase in polarization resistance indicating that α’ may enhance corrosion resistance in chloride environments by increasing passivation.