Cr precipitation in neutron irradiated industrial purity Fe–Cr model alloys

The microstructure of four neutron irradiated Fe–Cr model alloys of industrial purity (Fe–2.5%Cr, Fe–5%Cr, Fe–9%Cr and Fe–12%Cr) has been characterized by atom probe tomography (APT). Irradiation has been performed at 300 °C up to 0.6 dpa in MTR reactor. APT investigations confirmed the enhanced precipitation of α′ clusters as these clusters have only been observed in supersaturated model alloys. In addition a nonexpected family of clusters has been revealed due to irradiation induced segregation of impurities: NiSiPCr-enriched clusters. They might be associated to defect clusters invisible by transmission electron microscopy (TEM). A quantitative description of these objects is presented in this paper and results are compared with TEM and SANS data of the literature obtained on the same model alloy.