Response of nanostructured ferritic alloys to high-dose heavy ion irradiation

A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at −100 °C and 750 °C, as well as pre-irradiation reference material. Irradiation at −100 °C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti–Y–O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750 °C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr–W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.