Precipitation in neutron-irradiated Fe–Cu and Fe–Cu–Mn model alloys: a comparison of APT and SANS data

The size, number density and compositions of ultrafine copper–manganese precipitates that form in Fe–0.80at.% Cu and Fe–0.78at.% Cu–1.05at.% Mn model alloys that were neutron irradiated to a fluence of ∼1×1023 nm−2 (E>1 MeV) at 288 °C have been estimated by atom probe tomography and small-angle neutron scattering (SANS) experiments. The number density of precipitates was approximately an order of magnitude higher in the Fe–Cu–Mn alloy than in the Fe–Cu alloy. A direct comparison of the microstructural parameters estimated by each technique revealed good agreement between the radii of gyration and the number densities. However, the copper content in precipitates inferred from SANS was significantly higher than estimated from the atom probe results.