Next generation fast spectrum reactors require structural materials that can tolerate higher temperature and radiation damage compared to the currently used metal alloys. It has been discovered that the ferritic steels having bcc structure have higher swelling and creep resistance than the fcc austenitic steels. However, once the ferritic steels reach the steady state swelling regime, they can end up with considerable swelling. Radiation damage resistance in metals is directly correlated with the microstructure. In terms of microstructure tailoring to reduce radiation damage, the density of sinks (dislocations, grain boundaries, phase boundaries, twin boundaries etc.) can be increased. In this research, engineering alloys were produced with increased sink densities by various processing methods in order to improve swelling resistance. Various alloys of EK-181, HT-9 and 14YWT were processed by high pressure torsion (HPT), high rate shock deformation and hydrostatic extrusion, respectively. The effects of the resultant microstructures on the irradiation response of the materials were investigated with special interest paid to the influence of grain boundaries, phase boundaries and dislocations on swelling. In this study, we reported that initial stable and homogenous microstructure is the key to determine swelling resistance. Homogenously distributed nano-sized oxide dispersoids act as sinks for defects and help to stabilize microstructures through pinning dislocations and grain boundaries. The stability of oxide dispersoids is determined by irradiation conditions and key parameters influencing dispersoids' stability are identified. The study is important for development of accident tolerant components for fast reactors.
