Understanding the effect of minor alloying elements on helium bubble formation in ferritic-martensitic steels

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

Journal of Nuclear Materials Pub Date : 2025-07-20 DOI:10.1016/j.jnucmat.2025.156045

Xingyu Liu , Jonathan Poplawsky , Yongqiang Wang , Xinyuan Xu , Xiang (Frank) Chen , Xing Wang

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Abstract

Ferritic-martensitic steels are promising structural materials for advanced nuclear reactors. To minimize long-term radioactivity, reduced-activation ferritic-martensitic steels have been developed by substituting high-activation elements like Ni and Mo with low-activation elements such as W. However, the impact of these alloying modifications on helium bubble formation, which plays a key role in material swelling, remains unclear. In this study, we compared helium bubble formation in ferritic-martensitic steel T91 and reduced-activation ferritic-martensitic steel F82H. Both materials were irradiated with sequential 100 keV, 150 keV, and 200 keV helium ions to a dose of 0.5 dpa and a helium concentration of 9000 appm at 500 °C. The helium bubbles in F82H exhibited a larger average size and a lower density than those in T91, suggesting differences in minor alloying elements may influence the bubble growth. To investigate the effects of these alloying elements, we characterized radiation-induced segregation near bubbles and grain boundaries. Prominent Ni-Mn-Si enriched clusters were found near bubbles in T91, while only Mn-Si enriched clusters were found near bubbles in F82H. In addition, the obvious Cr enrichment near grain boundaries was absent around bubbles in both steels. The different segregation trends among elements revealed the variations in element diffusion mechanisms and the different sink biases between bubbles and grain boundaries. Cr enrichment near grain boundaries is mostly driven by interstitial-mediated diffusion. However, since bubble growth relies on net vacancy flux, vacancy-mediated diffusion plays a dominant role in controlling element segregation near bubbles. Therefore, Cr enrichment was not found near bubbles. Because of preferential vacancy-drag diffusion for Ni, Si and Mn, these elements were enriched near bubbles. Due to the strong binding energies of vacancies with these solute atoms, the vacancy diffusivity can be reduced near these solutes. Therefore, the more prominent Ni-Si-Mn clustered near helium bubbles in T91 lead to stronger suppression of helium bubble growth compared to F82H.

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了解微量合金元素对铁素体-马氏体钢中氦泡形成的影响

铁素体-马氏体钢是一种很有前途的先进核反应堆结构材料。为了将长期放射性降到最低，人们通过用w等低活化元素取代Ni和Mo等高活化元素来开发低活化铁素体马氏体钢。然而，这些合金化修饰对氦泡形成的影响尚不清楚，而氦泡在材料膨胀中起着关键作用。在本研究中，我们比较了铁素体-马氏体钢T91和低活化铁素体-马氏体钢F82H中氦泡的形成。在500°C下，分别用100 keV、150 keV和200 keV的氦离子照射两种材料，剂量为0.5 dpa，氦浓度为9000 appm。与T91相比，F82H中氦气泡的平均尺寸更大，密度更低，表明少量合金元素的差异可能影响了气泡的生长。为了研究这些合金元素的影响，我们对气泡和晶界附近的辐射诱导偏析进行了表征。T91在气泡附近发现了明显的Ni-Mn-Si富集团簇，而F82H在气泡附近只发现了Mn-Si富集团簇。此外，两种钢在气泡周围均没有晶界附近明显的Cr富集。元素之间的不同偏析趋势揭示了元素扩散机制的差异以及气泡与晶界之间不同的沉降偏差。晶界附近的Cr富集主要由间隙介导的扩散驱动。然而，由于气泡的生长依赖于净空位通量，空位介导的扩散在控制气泡附近元素偏析方面起主导作用。因此，在气泡附近没有发现Cr富集。由于Ni、Si和Mn的优先空位-阻力扩散，这些元素在气泡附近富集。由于空位与这些溶质原子具有很强的结合能，空位的扩散系数可以在这些溶质附近降低。因此，T91中聚集在氦气泡附近的Ni-Si-Mn比F82H对氦气泡生长的抑制更强。

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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.