Response of reduced activation ferritic steels to high-fluence ion-irradiation

Effects of high-fluence irradiation in fusion-relevant helium prod-action c ondition on defect cluster formation and swelling of reduced activation fer ritic/martensitic steels (RAFs), JLF-1 (Fe-9Cr-2W-V-Ta) and F82H (Fe-8Cr-2W -V-Ta), have been investigated. Dual-ion (nickel plus helium ions) irradiat ion using electrostatic accelerators was adopted to simulate fusion neutron environment. The irradiation has been carried out up to a damage level of 100 displacement per atom (dpa) at around 723 K, at the HIT facility in the University of Tokyo. Thin foils for transmission electron microscopy (TEM) were prepared with a focused ion beam (FIB) microsampling system. The syst em enabled not only the broad cross-sectional TEM observation, but also the detailed study of irradiated microstructure, since unfavorable effects of ferromagnetism of a ferritic steel specimen were completely suppressed with this system by sampling a small volume in interests from the irradiated ma terial. (C) 2001 Elsevier Science B.V. All rights reserved.