Abstract The strengthening of metals by nano-scale obstacles is mainly attributed to the impediment to glide dislocations offered by these obstacles. It is important to understand the mechanisms for dislocation bypass of obstacles having nano-scale dimension, including the atomic-scale structure changes sustained by both obstacles and dislocations after the bypass process. Recently, atomic-scale modeling has provided much insight into obstacle interactions involving a single dislocation. However, the more naturally occurring scenarios involving a sequence of encounters with arrays of moving dislocations are not as well understood owing to prohibitively large length scale requirements for atomistic models. In this study, we utilize a novel multiscale concurrent atomistic-continuum method to simulate a sequence of interactions between glide dislocations in an array with a spherical nano-obstacle (either a void or an impenetrable precipitate) in Al. In the case of a void, the bypassing array of dislocations progressively weakens the void until it splits the originally spherical void into two hemispheres. In the case of a large impenetrable precipitate, sequential dislocations in the array bypass via alternating mechanisms of Orowan looping and Hirsch looping. The residual dislocation loop created around the precipitate by the bypass of the first dislocation is completely removed by the passage of the subsequent dislocation. These mechanisms can benefit the design of materials that are reinforced with nanophase inhomogeneities to achieve ultra high strength.

中文翻译：

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平面阵列中与位错的顺序障碍相互作用

摘要 纳米级障碍物对金属的强化主要是由于这些障碍物对滑动位错的阻碍。了解纳米级障碍物的位错绕过机制很重要，包括绕过过程后障碍物和位错所持续的原子级结构变化。最近，原子尺度建模为涉及单个位错的障碍相互作用提供了很多见解。然而，由于对原子模型的长度尺度要求过高，涉及一系列与移动位错阵列相遇的更自然发生的场景并没有得到很好的理解。在这项研究中，我们利用一种新的多尺度并发原子连续谱方法来模拟阵列中滑移位错与 Al 中球形纳米障碍物（空隙或不可穿透的沉淀物）之间的一系列相互作用。在空隙的情况下，绕过的位错阵列逐渐削弱空隙，直到它将最初的球形空隙分裂成两个半球。在大的不可穿透的沉淀物的情况下，阵列中的顺序位错通过 Orowan 环和 Hirsch 环的交替机制绕过。由第一个位错的旁路在沉淀物周围产生的残余位错环被随后的位错通过完全去除。这些机制有利于通过纳米相不均匀性增强材料的设计，以实现超高强度。