Lin Yan-Ru, Zhao Yajie, Su Yi-Feng, Byun Thak Sang
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996, USA.
Materials (Basel). 2024 Sep 28;17(19):4763. doi: 10.3390/ma17194763.
Nanostructured ferritic alloys (NFAs), such as oxide-dispersion strengthened (ODS) alloys, play a vital role in advanced fission and fusion reactors, offering superior properties when incorporating nanoparticles under irradiation. Despite their importance, the high cost of mass-producing NFAs through mechanical milling presents a challenge. This study delves into the microstructure-mechanical property correlations of three NFAs produced using a novel, cost-effective approach combining severe plastic deformation (SPD) with the continuous thermomechanical processing (CTMP) method. Analysis using scanning electron microscopy (SEM)-electron backscatter diffraction (EBSD) revealed nano-grain structures and phases, while scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectroscopy (EDS) quantified the size and density of Ti-N, Y-O, and Cr-O fine particles. Atom probe tomography (APT) further confirmed the absence of finer Y-O particles and characterized the chemical composition of the particles, suggesting possible nitride dispersion strengthening. Correlation of microstructure and mechanical testing results revealed that CTMP alloys, despite having lower nanoparticle densities, exhibit strength and ductility comparable to mechanically milled ODS alloys, likely due to their fine grain structure. However, higher nanoparticle densities may be necessary to prevent cavity swelling under high-temperature irradiation and helium gas production. Further enhancements in uniform nanoparticle distribution and increased sink strength are recommended to mitigate cavity swelling, advancing their suitability for nuclear applications.
纳米结构铁素体合金（NFA），如氧化物弥散强化（ODS）合金，在先进的裂变和聚变反应堆中起着至关重要的作用，在辐照下加入纳米颗粒时具有卓越的性能。尽管它们很重要，但通过机械研磨大规模生产NFA的高成本带来了挑战。本研究深入探讨了采用一种新颖、经济高效的方法将严重塑性变形（SPD）与连续热机械加工（CTMP）方法相结合生产的三种NFA的微观结构与力学性能之间的相关性。使用扫描电子显微镜（SEM）-电子背散射衍射（EBSD）进行分析揭示了纳米晶粒结构和相，而扫描透射电子显微镜（STEM）-能量色散X射线光谱（EDS）对Ti-N、Y-O和Cr-O细颗粒的尺寸和密度进行了量化。原子探针断层扫描（APT）进一步证实了不存在更细的Y-O颗粒，并对颗粒的化学成分进行了表征，表明可能存在氮化物弥散强化。微观结构与力学测试结果的相关性表明，尽管CTMP合金的纳米颗粒密度较低，但其强度和延展性与机械研磨的ODS合金相当，这可能归因于其精细的晶粒结构。然而，可能需要更高的纳米颗粒密度来防止高温辐照下的空洞肿胀和氦气产生。建议进一步提高纳米颗粒分布的均匀性并增加汇强度以减轻空洞肿胀，从而提高它们在核应用中的适用性。
