The atomic structure of crystal defects such as dislocations, grain or phase boundaries, control these defects’ properties: their mobility, ability to cross-slip, or solute segregation. These crystal defects can be conveniently studied by atomistic simulations and one then needs to transfer relevant information at the upper scale to model microstructures containing a large number of defects, e.g., a polycrystal. Here, we propose an atomistic to continuum mechanics crossover method that (i) represents the atomic structure of dislocations cores by an appropriate Nye dislocation density tensor field and (ii), captures quantitatively the short and long range mechanical fields of defects. For (i), we propose a modified and improved interpolation method based on the original work by Hartley and Mishin. For (ii), we use a field dislocation mechanics framework that rigorously calculates/evaluates the mechanical fields associated with any Nye dislocation density distribution. The transfer method relies on molecular static calculations using two energetic models — ab-initio for screw dislocation core simulations in tungsten, and EAM potential for low and large angle grain boundaries in copper. Our findings demonstrate the effectiveness of the proposed approach in reconstructing the Burgers vector, and continuous strain and rotation fields. The framework is further applied to analyze the elastic interactions between extrinsic edge dislocations and a low angle grain boundary in copper.

中文翻译：

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位错密度场晶体缺陷的原子到连续介质力学描述：在位错和晶界上的应用

位错、晶粒或相界等晶体缺陷的原子结构控制着这些缺陷的特性：它们的迁移率、交叉滑移的能力或溶质偏析。这些晶体缺陷可以通过原子模拟方便地研究，然后需要在较高尺度上传输相关信息来模拟包含大量缺陷的微观结构，例如多晶。在这里，我们提出了一种原子到连续介质力学的交叉方法，该方法（i）通过适当的奈位错密度张量场表示位错核心的原子结构，并且（ii）定量捕获缺陷的短程和长程机械场。对于 (i)，我们在 Hartley 和 Mishin 的原始工作的基础上提出了一种修改和改进的插值方法。对于 (ii)，我们使用场位错力学框架来严格计算/评估与任何奈位错密度分布相关的机械场。该传递方法依赖于使用两种能量模型的分子静态计算——从头算起用于钨中的螺旋位错核心模拟，以及用于铜中的小角度和大角度晶界模拟的 EAM 势。我们的研究结果证明了所提出的方法在重建伯格斯矢量以及连续应变和旋转场方面的有效性。该框架进一步应用于分析铜中外在刃位错和小角度晶界之间的弹性相互作用。