SANS investigation of irradiation-induced phase separation in a binary Fe-Cr alloy

Ferritic-martensitic chromium steels are candidate materials for future applications in both Gen-IV fi ssion and fusion technology. Investigations of binary Fe-Cr alloys will contribute to the understanding of the behaviour of more complex alloys. The presented SANS results are focused on a Fe-9at%Cr alloy neutron-irradiated up to neutron doses of 0.6 and 1.5 dpa. We have observed a pronounced increase of scattering cross-sections for both magnetic and nuclear scattering. The A-ratio is about 2.8 for both irradiation conditions. This value is far from a value of 1.45 corresponding to nanovoids as scattering objects. This indicates that the irradiation-induced clusters are different from pure nanovoids and must contain Cr-atoms with the same or very similar average composition for both irradiation conditions. The composition of the clusters will be discussed in more detail. The size distributions of irradiation-induced defects have been calculated. The volume fraction of clusters increases slightly with neutron dose.