| Abstract Scope |
Oxide dispersion strengthened (ODS) alloys are candidate materials for the first wall/blanket structures in fusion reactors. However, solute nano-cluster behavior under neutron damage (ballistic dissolution, reprecipitation, nanocluster alterations) is not well-understood in these alloys. At ORNL, two ODS alloys: 20%Cr-5.5%Al based PM2000 and 14%Cr based MA957 were irradiated in the High Flux Isotope Reactor at 300°C to ~3-80 dpa. Previously, we revealed transformation of nano-dispersoids into amorphous, nano-porous structures in ~80 dpa irradiated PM2000. Here, we reveal that in addition to Cr-rich α’ phase separation, unexpected Al/Ti nano-clustering occurred in the PM2000 matrix. Likewise, irradiated MA957 suffered Ni/Ti nano-clustering. By combining analytical scanning electron transmission microscopy (STEM), atom probe tomography (APT) and Vickers micro-hardness tests with hardening models, we will correlate the contribution of solute nano-clustering to hardening of ODS alloys. Research sponsored by the U.S. Department of Energy, Office of Fusion Energy Sciences, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. |