Nanoindentation and TEM applied to ion-irradiated Fe-Cr alloys

9-18% Cr steels and oxide dispersion strengthened (ODS) steels being candidate structural materials for future nuclear applications for reasons such as resistance to swelling, irradiation creep and oxidation suffer hardening and embrittlement due to neutron irradiation. Ion irradiation has proven useful to simulate neutron irradiation effects without the drawbacks of producing radioactive material and being restricted to time consuming and expensive in-reactor irradiations. We have applied ion irradiation in combination with nanoindentation to study the irradiation-induced hardening of binary Fe-Cr alloys, 9% Cr steels and experimental ODS alloys. The details of the approach are specified and the effects of Cr content and irradiation conditions including dual-beam irradiations are considered. Transmission electron microscopy is used to characterize nanoscale oxide particles and irradiation-induced dislocation loops. The dimensionless obstacle strength is estimated. On a scale assigning unity to non-shearable obstacles, we have found a ranking from about 0.012 for Cr-rich α’-phase particles, 0.1 to 0.2 for ODS nanoparticles up to about 0.5 for dislocation loops.