Through-thickness fracture behavior of neutron-irradiated nuclear graphite NBG-17 Using X-ray micro-CT

IF 3.2 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2025-08-23 DOI:10.1016/j.jnucmat.2025.156119

Gongyuan Liu , Swapnil Morankar , Arvin Cunningham , William Chuirazzi , William Windes , Jing Du , Aman Haque

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Abstract

Achieving precise control over crack propagation in nuclear graphite and conducting quantitative analysis remain challenging. In this study, the through-thickness fracture behavior of pristine and neutron-irradiated (700 °C, ∼7 dpa) NBG-17 nuclear graphite was investigated using split-disc testing coupled with micro-computed tomography (micro-CT). A notably lower number of micropores was observed in the neutron-irradiated specimen. The fracture toughness of neutron-irradiated NBG-17 was measured to be 1.45 MPa√m, compared to 1.17 ± 0.05 MPa√m for the pristine specimen. In both materials, cracks were found to initiate at the filler–binder interface, and often correlated with microstructural features such as pores and thermal cracks. Crack bridging and deflections emerged as the primary toughening mechanisms in both unirradiated and irradiated NBG-17. However, compared with the pristine specimen, the cracks in the neutron-irradiated specimen were more likely to grow trans granularly, resulting in less deflected crack paths. The reduced micro-porosity and strengthened filler–binder boundaries were considered to be the cause of the observed differences in crack morphologies. This study provides a qualitative analysis of the fracture behavior of neutron-irradiated nuclear graphite in the absence of radiolytic oxidation.

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中子辐照核石墨NBG-17的x射线显微ct穿透断裂行为

实现核石墨裂纹扩展的精确控制和定量分析仍然是一个挑战。在这项研究中，使用裂盘测试和微计算机断层扫描（微ct）研究了原始和中子辐照（700°C, ~ 7 dpa） NBG-17核石墨的穿透厚度断裂行为。在中子辐照的样品中，微孔的数量明显减少。中子辐照后的NBG-17的断裂韧性为1.45 MPa√m，而原始试样的断裂韧性为1.17±0.05 MPa√m。在这两种材料中，裂纹都是在填料-粘结剂界面处开始的，并且通常与微观结构特征（如孔隙和热裂纹）相关。在未辐照和辐照的NBG-17中，裂纹桥接和挠曲是主要的增韧机制。然而，与原始试样相比，中子辐照后试样的裂纹更倾向于穿晶生长，导致裂纹路径偏转较少。微孔隙率的降低和填料-粘结剂边界的增强被认为是造成裂纹形貌差异的原因。本研究对中子辐照核石墨在没有放射性氧化作用下的断裂行为进行了定性分析。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Nuclear Materials 工程技术-材料科学：综合

CiteScore

5.70

自引率

25.80%

发文量

601

审稿时长

63 days

期刊介绍： The Journal of Nuclear Materials publishes high quality papers in materials research for nuclear applications, primarily fission reactors, fusion reactors, and similar environments including radiation areas of charged particle accelerators. Both original research and critical review papers covering experimental, theoretical, and computational aspects of either fundamental or applied nature are welcome. The breadth of the field is such that a wide range of processes and properties in the field of materials science and engineering is of interest to the readership, spanning atom-scale processes, microstructures, thermodynamics, mechanical properties, physical properties, and corrosion, for example. Topics covered by JNM Fission reactor materials, including fuels, cladding, core structures, pressure vessels, coolant interactions with materials, moderator and control components, fission product behavior. Materials aspects of the entire fuel cycle. Materials aspects of the actinides and their compounds. Performance of nuclear waste materials; materials aspects of the immobilization of wastes. Fusion reactor materials, including first walls, blankets, insulators and magnets. Neutron and charged particle radiation effects in materials, including defects, transmutations, microstructures, phase changes and macroscopic properties. Interaction of plasmas, ion beams, electron beams and electromagnetic radiation with materials relevant to nuclear systems.