b'Figure 3. (a) Color inverted annular dark field (ADF) STEM image of the High N alloy after irradiation with 1.5Elevated N content in the ferritic/martensitic steel HT9 has MeV protons to 1 dpa at 300C withbeen found to decrease irradiation hardening after 1 dpa many visible loops. Imaging down the [100] zone axis (selected areaof 1.5 MeV protons at 300 C, and likely reduce irradiation diffraction pattern (SADP) in theswelling at higher irradiation doses, both of which improve upper-right corner of (a)) satisfies theperformance in next-generation reactor applications.gb criteria for the imaging of nearly every variant of a100 and a/2111 dislocations. The yellow arrows point to an example of each of the possible common dislocation loop variants. (b)showed that the high N alloy exhibitsAccomplishments:A schematic of the indexed dislocationreduced irradiation hardening relativeTo understand the effect of N on the loops from (a). Because the loops areto the low N alloy. Additionally, basedirradiation hardening behavior of F/M assumed to be circular and tend to form on distinct planes ({100} and {111}), theon the defect structure of the alloys,steel three primary technical goals were projected shape of the dislocation loopsin particular the dislocation loopcarried out: the production and initial based on the viewing direction of thetype, size, and number density therecharacterization of the experimental crystal can be used to identify eachappears to be a decrease in SIA clusteralloys, the proton irradiation of the dislocation loop; the major axis of each ellipse corresponds to the diameter ofmobility with increasing N content.alloys, and the characterization of the dislocation loop in plane. (c) TheAn example of the dislocation loopthe irradiated experimental alloys. distribution of a100 and a/2111structure is shown in Figure 3 alongFirst the experimental alloys were dislocation loop diameters. The meanwith chart summarizing differencesdesigned and produced, and the initial diameter is represented by the x, and outliers are shown as points above boxin loop size across the alloys. Overall,microstructure and properties were and whisker plots. this work indicates that increasingcharacterized. The low and high N the overall N content in ferritic/ alloys were designed at LANL and martensitic alloys may be beneficial toproduced by Sophisticated Alloys while irradiated properties. the mid N alloy was designed at CSM 110 2021|AFC ACCOMPLISHMENTS'