Abstract Oxide Dispersion Strengthened (ODS) steels are candidates for fuel cladding materials in sodium-cooled fast reactors and for structural materials in nuclear fusion power reactors. The effect yttrium-titanium-oxygen (Y-Ti-O) nano-oxide precipitates within ODS steels have on the micromechanical deformation mechanisms has been investigated. The aim is to assess the extent of any direct link between the Y-Ti-O dispersion and nanoindentation hardness, using electron backscatter diffraction, transmission electron microscopy (TEM), and atom probe tomography (APT) studies of a Fe-14Cr-3W-0.2Ti-0.25Y2O3 (wt%) ODS steel at room temperature. Y-Ti-O nanoclusters had a non-uniform distribution and average number density that ranged from 5.8 ± 0.1 × 1023 to 1.3 ± 0.1 × 1024 m−3 and Guinier radii ranging from 1.8 ± 0.2 nm to 2.1 ± 0.2 nm. Surprisingly, the local Y-Ti-O distribution did not correlate strongly with the nanohardness, indicating that the dominant hardening mechanisms was at best only weakly related to the Y-Ti-O distribution. Instead, scanning TEM and APT confirmed that the dominant hardening mechanism was due to the grain boundary refinement, and was further enhanced by tungsten enrichment to ~3.5 at.% at grain boundaries.

中文翻译：

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氧化物弥散强化钢中纳米压痕变形的电子显微镜和原子探针层析成像

摘要 氧化物弥散强化（ODS）钢是钠冷快堆燃料包壳材料和核聚变反应堆结构材料的候选材料。研究了 ODS 钢中钇-钛-氧 (Y-Ti-O) 纳米氧化物沉淀物对微观机械变形机制的影响。目的是使用 Fe-14Cr-3W 的电子背散射衍射、透射电子显微镜 (TEM) 和原子探针断层扫描 (APT) 研究来评估 Y-Ti-O 分散与纳米压痕硬度之间的任何直接联系的程度-0.2Ti-0.25Y2O3 (wt%) ODS 钢在室温下。Y-Ti-O 纳米团簇分布不均匀，平均数密度范围为 5.8 ± 0.1 × 1023 至 1.3 ± 0.1 × 1024 m-3，吉尼尔半径范围为 1.8 ± 0.2 nm 至 2.1 ± 0.2 nm。出奇，局部 Y-Ti-O 分布与纳米硬度没有很强的相关性，表明主要的硬化机制至多仅与 Y-Ti-O 分布微弱相关。相反，扫描 TEM 和 APT 证实主要的硬化机制是由于晶界细化，并且通过在晶界处富集钨至~3.5 at.% 进一步增强。