Abstract
FeCrAl alloys are currently under consideration for accident-tolerant fuel
cladding applications in light water reactors (LWRs) due to their superior high
temperature oxidation and corrosion resistance compared to the Zr-based alloys
currently employed. However, their performance could be limited by precipitation
of a Cr-rich α' phase which tends to embrittle high-Cr ferritic Fe-based
alloys. In this study, four FeCrAl model alloys with 10-18 at.% Cr and 5.8-9.3
at.% Al were neutron irradiated to uences up to 7.73 x 10^21 (E >0.1 MeV) at
a target temperature of 320 ‰°C. Small angle neutron scattering (SANS) techniques
were coupled with atom probe tomography (APT) in order to assess the
composition and morphology of the resulting α' precipitates. It was demonstrated
that Al additions partially destabilize the α' phase, generally resulting
in precipitates with lower Cr contents when compared to binary Fe-Cr systems.
Precipitate morphology evolution with dose agreed with trends predicted by the
LSW/UOKV models, suggesting that α' precipitation in irradiated FeCrAl is a
diffusion-limited process with similar coarsening mechanisms to thermally aged
ferritic materials.
