SUMMARY

The overall purpose of this dissertation is to explore the complex mechanisms underneath the irradiation resistance of metallic phase boundaries. Materials in nuclear applications are constantly exposed to harsh radiation environments throughout their service lives. Interactions between high energy radiation sources and the atoms of the material will inevitably produce nanoscale defects in the crystal lattice. In large quantities, these radiation defects are known to cause swelling, embrittlement, and nano-scale crack growth, all of which negatively impact the mechanical performance of the material and can possibly lead to component failure. One of the most promising solutions to defect accumulation is to leverage the defect sink properties of the grain boundaries. By creating new nanocomposites/laminates/multilayers with high concentrations of boundaries, modern materials engineers are able to significantly improve the irradiation resistance of conventional metals. In order to further refine the design of these next-gen materials, it is crucial to first understand the complex relationships between radiation defects and boundaries over a large range radiation doses. To this end, we have employed multiple advanced atomistic modeling methods in this dissertation to examine the various aspects of radiation defect production, accumulation, and evolution, as well as the interaction of radiation damage with phase boundaries and its effects on mechanical performance.