b'Figure 2. A scanning transmission electron microscopy bright field image of dislocations in commercially irradiated IronClad. Traced loops, including face- and edge-on a{001} loops and a/2{111} loops are shown in blue and red, respectively, while smaller black dot defects are shown in black. Dislocations deviating from characteristic loop morphologies are categorized as preexisting network dislocations in greenFigure 3. Atom probe tomography (APT) results reveal Cr-rich segregation in commercially irradiated IronClad segments. On the left, an APT reconstruction shows a high density of Cr-rich surfaces using 19% enriched iso-concentration surfaces, while the right image shows a proximity histogram quantifying the level of Cr-enrichment and (Fe,Al)-depletion within identified Cr-rich precipitatesin Figures 2 and 3. Following irradia- changes to mechanical properties tion, a high density of dislocationproduced by neutron irradiation in loops was imaged along charac- FeCrAl candidate alloys are needed teristic habit planes in the body- to fully understand the wide variety centered cubic crystal lattice. Theseof processing parameters and alloy loops are visible in Figure 2 takencompositions that are currently being from an upper segment of the rod.evaluated for use as BWR cladding. In addition, Cr-rich precipitationThis requires irradiation of new candi-was also revealed using atom probedate materials as well as historical tomography. The high aluminumalloys to understand how processing content, coupled with the relativelyand alloying improvements impact low irradiation temperature,properties following irradiation. resulted in core Cr concentrationsIrradiation positions in HFIR are an reaching 40% Cr, as shown in theideal location for rapid screening of proximity histogram in Figure 3. several different alloys using standard-More data on the fundamentalized irradiation test designs. A series of irradiations were designed, and 76 2023|AFC ACCOMPLISHMENTS'