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内容記述 |
In F82H steel, a promising structural material for fusion reactors, the accelerating deterioration in mechanical properties is of significant concern due to the accumulation of He by 14-MeV neutron irradiation. The aim of the present study is to elucidate the morphology of He bubbles in F82H steel by employing microscopic analysis. The experimental approach entailed the irradiation of single- and dual-ion beams up to 80 dpa at 703 K subsequently, a comprehensive analysis using TEM/STEM/EF-TEM was performed to study the irradiation defects, including dislocation loops and helium bubbles. A STEM analysis revealed a dislocation loop density of 2-5 x1021 m-3, and the He led to a decrease in size of loop. For the He bubble evaluation, TEM mode encountered difficulties in discerning bubbles smaller than 2 nm, while the contrast is insufficient for the detection of fine bubbles in the STEM mode. Conversely, EF-TEM mode, exhibiting sensitivity to material density fluctuations, detected ~1 nm bubbles with high signal-to-noise ratio. The density of the bubble was estimated to be 6-7 x 1022 m?3, exhibiting a modest increase with increasing dose. The presence of minor peaks at approximately 7 and 18 nm at 20 dpa diminished at higher doses, reducing the multimodal distribution. It has been demonstrated that coarse bubbles persist but decrease in density, which poses a concern for material integrity due to the presence of coarse bubbles under high-dose conditions. |
