| Abstract Scope |
Yttrium hydride, YHₓ, is a promising moderator and reflector material for advanced nuclear systems due to its high hydrogen density and thermodynamic stability. However, its microstructural response to neutron irradiation, including defect cluster formation, phase decomposition, and grain-boundary evolution, remains poorly quantified, representing a critical gap for material qualification. This study characterizes ATR-irradiated YHₓ specimens exposed at 600, 700, and 800 °C, benchmarked against an unirradiated reference to isolate irradiation-induced damage from fabrication features. SEM-EDS and EBSD assess grain structure, texture, local misorientation, grain-boundary character, and elemental redistribution. Site-specific FIB lift-outs enable TEM/STEM analysis, quantifying defect clusters, dislocation loops, cavities, secondary phases, and grain-boundary evolution as functions of irradiation temperature. Conducted under an NSUF-funded Super Rapid Turnaround Experiment, this work provides a systematic, multi-temperature post-irradiation examination dataset for YHₓ, building foundational understanding of irradiation-driven damage accumulation, phase stability, and microstructural integrity to inform qualification frameworks for advanced nuclear applications. |