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Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

机译：BCC钨中氢与间隙缺陷和位错相互作用的多尺度模拟

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摘要

In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The dynamics of hydrogen exchange between the plasma and the material is controlled by pressure, temperature, and also by the energy barriers characterizing hydrogen diffusion in the material, trapping and de-trapping from defects. In this work, we extend the treatment of interaction of hydrogen with vacancy-type defects, and investigate how hydrogen is trapped by self-interstitial atom defects and dislocations. The accumulation of hydrogen on dislocation loops and dislocations is assessed using a combination of density functional theory (DFT), molecular dynamics with empirical potentials, and linear elasticity theory. The equilibrium configurations adopted by hydrogen atoms in the core of dislocations as well as in the elastic fields of defects, are modelled by DFT. The structure of the resulting configurations can be rationalised assuming that hydrogen atoms interact elastically with lattice distortions and that they interact between themselves through short-range repulsion. We formulate a two-shell model for hydrogen interaction with an interstitial defect of any size, which predicts how hydrogen accumulates at defects, dislocation loops and line dislocations at a finite temperature. We derive analytical formulae for the number of hydrogen atoms forming the Cottrell atmosphere of a mesoscopic dislocation loop or an edge dislocation. The solubility of hydrogen as a function of temperature, pressure and the density of dislocations exhibits three physically distinct regimes, dominated by the solubility of hydrogen in a perfect lattice, its retention at dislocation cores, and trapping by long-range elastic fields of dislocations.
机译：在聚变托卡马克中，氢同位素的等离子体在分流器的表面与钨接触。在大部分材料中，氢浓度分布趋向于在入射离子通量与离子的俘获和从缺陷（天然的或由离子和中子辐照产生的缺陷）的释放之间动态平衡。等离子体与材料之间氢交换的动力学受到压力，温度以及能量屏障的控制，该能量屏障表征了氢在材料中的扩散，从缺陷的俘获和去俘获。在这项工作中，我们扩展了氢与空位型缺陷相互作用的处理，并研究了氢如何被自填隙原子缺陷和位错捕获。使用密度泛函理论（DFT），具有经验电势的分子动力学和线性弹性理论的组合来评估氢在位错环和位错上的积累。 DFT可以模拟位错核心以及缺陷弹性场中氢原子所采用的平衡构型。假设氢原子与晶格畸变发生弹性相互作用，并且氢原子之间通过短程排斥相互作用，则可以合理化最终结构的结构。我们为氢与任何尺寸的间隙缺陷的相互作用建立了一个两层模型，该模型预测了氢在有限温度下如何累积在缺陷，位错环和线位错上。我们推导了形成介观位错环或边缘位错的Cottrell气氛的氢原子数目的解析公式。氢的溶解度随温度，压力和位错密度的变化表现出三种物理上不同的状态，主要由氢在完美晶格中的溶解度，氢在位错核心处的保留以及位错的远距离弹性场所俘获。

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  • 来源
    《Nuclear fusion》 |2018年第1期|016006.1-016006.18|共18页
  • 作者

    A. De Backer; D.R. Mason; C. Domain; D. Nguyen-Mann; M.-C. Marinica; L. Ventelon; C.S. Becquart; S.L. Dudarev;

  • 作者单位

    CCFE, UK Atomic Energy Authority, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom;

    CCFE, UK Atomic Energy Authority, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom;

    EDF Lab Les Renardieres, Dpt MMC, F-77250 Moret sur Loing, France;

    CCFE, UK Atomic Energy Authority, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom,Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom;

    DEN-Service de Recherches de Metallurgie Physique, CEA, Universite Paris-Saclay, F-91191, Gif-sur-Yvette, France;

    DEN-Service de Recherches de Metallurgie Physique, CEA, Universite Paris-Saclay, F-91191, Gif-sur-Yvette, France;

    Univ. Lille, CNRS, INRA, ENSCL, UMR 8207, UMET, Unite Materiaux et Transformations, F-59000, Lille, France;

    CCFE, UK Atomic Energy Authority, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom,Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    hydrogen; fusion; dislocation; density functional theory; linear elasticity; Cottrell atmosphere; solubility;

    机译：氢;融合错位;密度泛函理论;线弹性科特雷尔气氛;溶解度;

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