Y₂O₃ and Y₂Ti₂O₇ nanoparticles stability in oxide dispersion strengthened steels under hydrogen irradiation at elevated temperature

Oxide dispersion-strengthened steels with Y₂O₃ and Y₂Ti₂O₇ nanoparticles (NPs) and Chinese low-activation ferritic/martensitic steel (CLF) samples were fabricated by the mechanical alloying method and sequentially irradiated at 550 °C with 50 keV H₂⁺ ions to various fluences. The hydrogen-bubble density and average bubble size are significantly higher in CLF steel. After irradiation, the size of NPs in YTO and YO steel reduced to ∼ 7 nm and ∼ 15 nm; finer NPs in YTO steel enhanced the resistance to the irradiation-induced defects. The absence of NPs in CLF causes the formation of dislocation networks. Y₂Ti₂O₇ NPs phases in YTO steel are highly stable and show semi-coherent orientation, while YAlO₃ NPs phases show incoherent orientation with the matrix. Y₂Ti₂O₇ NPs resist defect formation by reducing the internal stresses and obstructing dislocation networks. This study suggests that introducing Y₂Ti₂O₇ NP into ODS steel presents a promising approach to improving the resistance towards irradiation damage.