Corrosion behavior of Nb-doped FeCrAl alloy in 500°C steam

Abstract

The corrosion behavior of Fe-13Cr-4Al-2.2Mo, a candidate cladding material for accident tolerant fuel, doped with varying concentrations of Nb (0, 0.5, 1.0, and 1.5 wt%), was investigated under conditions of 500°C/10.3 MPa superheated steam. Upon exposure, a triple-layer oxide film comprising outer, inner, and diffusion oxide layers was formed. The results indicate that the addition of Nb significantly enhances the corrosion resistance of this alloy by reducing the thickness and porosity of the oxide film. The enhanced volume diffusion rate of Al and Cr, facilitated by the solid solution Nb, along with the inhibited inward diffusion of oxidant ions along grain boundaries owing to Laves phase precipitates, contributed to the enhanced corrosion resistance of the Nb-doped Fe-13Cr-4Al-2.2Mo alloy.