辐照 α-铀中位错环的演化：一项原子尺度信息赋能的团簇动力学研究
Evolution of dislocation loops in irradiated α-Uranium: An atomistically-informed cluster dynamics investigation
AI总结：
本文构建原子参数赋能的团簇动力学模型，结合 MD、超动力学与 DFT 对比，模拟辐照 α-U 中 SIA 环和空位环的各向异性形核长大，结果与 TEM 观察吻合。
摘要：
本文提出了一种由原子尺度信息赋能的平均场团簇动力学模型，用于研究辐照 α-U 中缺陷环的形核与长大。对中子辐照 α-U 的 TEM 分析表明，SIA 环和空位环分别在 (010) 和 (100) 晶面上演化，导致面心正交晶体发生各向异性肿胀。该团簇动力学模型紧密估算了辐照过程中此类环的累积。模型参数，即点缺陷 Ui 和 VU 分别与 SIA 环和空位环的结合能，以及点缺陷的扩散率，决定了缺陷团簇化现象的能量学和动力学。我们研究了缺陷环的晶体学，并在经典 MD 模拟中使用角度相关 EAM 势计算了点缺陷与此类环的结合能。通过在 LAMMPS 中使用 bond-boost 超动力学，研究了 Ui 和 VU 在 α-U 中的各向异性扩散。本文还报告了点缺陷扩散机制及相关迁移能，并与以往的 DFT 研究进行了比较。我们的 CD 模型在计算参数的误差范围内使用这些参数，在与中子辐照实验相似的剂量率和温度下预测缺陷团簇的数量。预测结果显示，小尺寸空位环发生累积，同时存在大量大型且不断长大的 SIA 环，这与 TEM 观察结果密切对应。
英文摘要：
An atomistically informed mean field cluster dynamics model has been presented to investigate the nucleation and growth of defect loops in irradiated α-U. TEM analysis of neutron irradiated α-U shows the evolution of SIA and vacancy loops on (010) and (100) crystallographic planes respectively, resulting in an anisotropic swelling of the face-centered orthorhombic crystal. The accumulation of such loops, on irradiation, has been closely estimated using the cluster dynamics model. Parameters of the model, namely, the binding energy of point defects, i.e., Ui and VU, to SIA and vacancy loops respectively and the diffusivity of point defects govern the energetics and kinetics of the defect clustering phenomenon. We have studied the crystallography of defect loops and computed the binding energy of point defects to such loops using an angular dependent EAM potential in classical MD simulations. Using bond-boost hyperdynamics in LAMMPS, the anisotropic diffusion of Ui and VU in α-U has been investigated. The mechanisms of point defect diffusion and the associated migration energies have also been reported and compared with previous DFT studies. Our CD model uses the computed parameters, within their error ranges, to predict the population of defect clusters with a dose-rate and temperature similar to the neutron irradiation experiments. The predictions show an accumulation of small sized vacancy loops along with a population of large and growing SIA loops which closely corresponds to the TEM observations.
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