ESTEEM3 project - Sri Tapasvi Nori
Title: Nano Particle Characterization and Grain Orientation Mapping for Ion-irradiated Oxide Dispersion Strengthened-Concentrated Solid Solution Alloys
Abstract: The novel ODS-CSAs have the best potential as Gen. IV reactor structural materials due to nanostructures. However, the research is limited. Thus, the proposed ESTEEM3 experiments will comprehensively study the impact of nanostructures on the synergy of mechanical properties and high-temperature radiation resistance by examining and analyzing the nanostructures and their stability after irradiation at 580℃ and 700℃. The ODS-14YWT will also be studied for comparison. The oxide particles hinder dislocation (particle strengthening) and grain boundary movement by suppressing recrystallization and grain growth and act as sinks for irradiation-induced defects such as vacancies and interstitials. Hence, their characteristics such as stoichiometry, crystallography, size, and number density will be evaluated. The stoichiometry of the oxide particles (Y2Ti2O7 or Y2Hf2O7 type) will determine the anticipated chemical stability following high-temperature irradiation. Crystallography will ascertain coherency and lattice misfit. The coherency, lattice misfit, size, and number density will influence the strengthening. The nanosized grains also strengthen via dense grain boundaries. Such effects are evident from high-hardness values measured for irradiated ODS-CSAs, comparable to or better than irradiated ODS-14YWT. The difference in hardness can be related to nanostructure characteristics. Irradiation can cause degradation via voids and dislocation loops, causing hardening, though it is limited. Grain boundaries also act as defect sinks; hence, grain sizes, orientations, and boundary parameters will be evaluated to determine the stability and sink strength. The other objectives of the research apart from ESTEEM3 experiments comprise examining the irradiation-induced defects such as voids and dislocation loops and their interaction with nanostructures and nanoindentation-induced dislocations.
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