Molecular-dynamics study of diffusional creep in uranium mononitride

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

Journal of Nuclear Materials Pub Date : 2025-09-12 DOI:10.1016/j.jnucmat.2025.156153

Mohamed AbdulHameed , Benjamin Beeler , Conor O.T. Galvin , Michael W.D. Cooper , Nermeen Elamrawy , Antoine Claisse

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Abstract

Uranium mononitride (UN) is a promising advanced nuclear fuel due to its high thermal conductivity and high fissile density. Yet, many aspects of its mechanical behavior and microstructural features are currently unknown. In this paper, molecular dynamics (MD) simulations are used to study UN's diffusional creep. Nanometer-sized polycrystals are used to simulate diffusional creep and to calculate an effective GB width. It is found that Nabarro-Herring creep is not dominant in the temperature range of 1700–2000 K and that the dominant diffusional creep mechanism is Coble creep with an activation energy of 2.28 ± 0.09 eV. A method is proposed to calculate the diffusional GB width and its temperature dependence in polycrystals. The effective GB width of UN is calculated as 2.69 ± 0.08 nm. This value fits very well with the prefactor of the phenomenological Coble creep formula. It is demonstrated that the most comprehensive thermal creep model for UN can be represented as the combination of our Coble creep model and the dislocation creep model proposed by Hayes et al.

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单氮化铀扩散蠕变的分子动力学研究

单氮化铀具有高导热性和高裂变密度的特点，是一种很有发展前途的先进核燃料。然而，其力学行为和微观结构特征的许多方面目前尚不清楚。本文采用分子动力学方法研究了UN的扩散蠕变。采用纳米尺寸的多晶模拟扩散蠕变并计算有效的GB宽度。结果表明，在1700 ~ 2000 K范围内，扩散蠕变机制不以Nabarro-Herring蠕变为主，以Coble蠕变为主，活化能为2.28±0.09 eV。提出了一种计算多晶中扩散GB宽度及其温度依赖性的方法。UN的有效国标宽度计算为2.69±0.08 nm。这个值与现象学的Coble蠕变公式的前因子非常吻合。研究表明，最全面的UN热蠕变模型可以用Coble蠕变模型和Hayes等人提出的位错蠕变模型的结合来表示。

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.