Abstract Molecular dynamics simulations are performed to investigate the impact of a coherent Σ3 (111) twin boundary on the plastic deformation behavior of Cu nanopillars. Our work reveals that the mechanical response of pillars with and without the twin boundary is decisively driven by the characteristics of initial dislocation sources. In the condition of comparably large pillar size and abundant initial mobile dislocations, overall yield and flow stresses are controlled by the longest, available mobile dislocation. An inverse correlation of the yield and flow stresses with the length of the longest dislocation is established and compared to experimental data. The experimentally reported subtle differences in yield and flow stresses between pillars with and without the twin boundary are likely related to the maximum lengths of the mobile dislocations. In the condition of comparably small pillar size, for which a reduction of mobile dislocations during heat treatment and mechanical loading occurs, the mechanical response of pillars with and without the twin boundary can be clearly distinguished. Dislocation starvation during deformation is more pronounced in pillars without the twin boundary than in pillars with the twin boundary because the twin boundary acts as a pinning surface for the dislocation network.

中文翻译：

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具有预先存在的位错的单晶和双晶Cu纳米柱的原子变形行为

摘要 进行分子动力学模拟以研究相干 Σ3 (111) 双晶界对 Cu 纳米柱塑性变形行为的影响。我们的工作表明，具有和不具有孪晶边界的柱子的机械响应决定性地由初始位错源的特征驱动。在相对较大的柱子尺寸和丰富的初始移动位错的条件下，整体屈服应力和流动应力由最长的可用移动位错控制。建立屈服应力和流动应力与最长位错长度的反相关并与实验数据进行比较。实验报告的有和没有双边界的柱子之间屈服和流动应力的细微差异可能与移动位错的最大长度有关。在相对较小的柱子尺寸的条件下，热处理和机械加载过程中发生移动位错的减少，可以清楚地区分有和没有双晶界的柱子的力学响应。变形过程中的位错饥饿在没有孪晶界的柱子中比在有孪晶界的柱子中更为明显，因为孪晶界充当了位错网络的钉扎面。可以清楚地区分有和没有双边界的支柱的机械响应。变形过程中的位错饥饿在没有孪晶界的柱子中比在有孪晶界的柱子中更为明显，因为孪晶界充当了位错网络的钉扎面。可以清楚地区分有和没有双边界的支柱的机械响应。变形过程中的位错饥饿在没有孪晶界的柱子中比在有孪晶界的柱子中更为明显，因为孪晶界充当了位错网络的钉扎面。