Post-irradiation annealing behaviour of oxide dispersion strengthened Fe-Cr alloys studied by nanoindentation

To study the nature of irradiation-induced nanofeatures in oxide dispersion strengthened (ODS) Fe-Cr alloys, post-irradiation isochronal thermal annealing up to 600 degrees C was performed for ODS Fe-9%Cr and Fe-14%Cr alloys ion-irradiated at 300 degrees C and 500 degrees C. Nanoindentation indicated hardening for all as-irradiated alloys and complete hardness recovery upon post-irradiation annealing. Cross-sectional TEM indicated an irradiation-induced defect band near peak damage mainly consisting of dislocation loops. Candidate mechanisms of recovery were critically evaluated. Shrinkage of loops via capture of thermal vacancies was found to correctly reflect the annealing behaviour of ODS Fe-9Cr irradiated at 300 degrees C.