Oxide dispersion strengthened (ODS) alloys containing high-density nano-oxides show excellent mechanical properties and irradiation tolerance. However, ODS alloys are often ultrafine-grained materials since the grain size of matrix is located between 100 and 1000 nm. Here, nanocrystalline and ultrafine-grained ODS alloys with different grain sizes (50 nm and 300 nm) were prepared by mechanical alloying and high-pressure consolidation techniques, which show exceptional thermal stability. To understand their irradiation response, the two alloys were irradiated with 400 keV helium ions to a fluence of 1 × 10¹⁷He⁺ /cm² at 350 ℃, 400 ℃ and 450 ℃. The results show that the size and volume fraction of helium bubbles in nanocrystalline ODS alloys increase when the irradiation temperature increases from 350 ℃ to 450 ℃. Grain boundaries (GBs) play a key role in bubble formation and evolution. We identified the bubble denuded zone (BDZ) near the GBs, but the width of the denuded zone narrowed and finally vanished with increasing helium concentration. Nanocrystalline ODS alloy with 50 nm grains (Y50) can disperse helium into much finer bubbles than ultrafine-grained ODS alloy with 300 nm grains (Y300) because of the extremely high density of GBs and oxide-matrix boundaries. To our best knowledge, Y50 alloy presents the best helium bubble suppression ability among all studied ODS and nanostructured ferritic alloys (NFA), which makes it a promising candidate material for using in fission and fusion nuclear reactors.

含有高密度纳米氧化物的氧化物弥散强化 (ODS) 合金显示出优异的机械性能和辐照耐受性。然而，ODS 合金通常是超细晶粒材料，因为基体的晶粒尺寸介于 100 和 1000 nm 之间。在这里，通过机械合金化和高压固结技术制备了具有不同晶粒尺寸（50 nm 和 300 nm）的纳米晶和超细晶 ODS 合金，具有出色的热稳定性。为了解它们的辐照响应，用 400 keV 的氦离子将两种合金辐照至 1 × 10 ¹⁷ He ⁺ /cm ²的注量350℃、400℃和450℃。结果表明，当辐照温度从350 ℃升高到450 ℃时，纳米晶ODS合金中氦气泡的尺寸和体积分数增加。晶界 (GB) 在气泡形成和演化中起着关键作用。我们确定了 GB 附近的气泡剥蚀区 (BDZ)，但剥蚀区的宽度随着氦气浓度的增加而变窄并最终消失。由于GBs和氧化物基质边界的极高密度，具有50 nm晶粒（Y50）的纳米晶ODS合金可以将氦气分散成比具有300 nm晶粒的超细晶粒ODS合金（Y300）更细的气泡。据我们所知，Y50 合金在所有研究的 ODS 和纳米结构铁素体合金 (NFA) 中表现出最好的氦气泡抑制能力，