Abstract The nucleation of lattice dislocations (LDs) from bimetal interfaces is critical to the interface-mediated deformation and strengthening mechanism in nanoscale multilayered metallic composites. Such nucleation not only depends on external loadings but also closely correlates with interfacial dislocation (ID) networks and their dynamic evolution. In this study, we focused on LD nucleation cooperating with IDs dynamic evolution from Zr/Nb bimetal interfaces following Pitch-Schrader and Burgers orientation relationships. To mimic the cross interactions between Zr and Nb atoms in molecular dynamic simulations, an empirical embedded-atom method potential was developed. The automatic Nye tensor analysis method was employed to directly identify the characteristics of IDs, which showed that: (1) many segments with obvious directivity, named main segments, were regularly distributed within IDs networks; and (2) main segments were connected by several atomic steps at regions where IDs intersected with each other. These characteristics have demonstrated, for the first time, the significant details of hcp/bcc interfaces. The further analyses of IDs dynamic evolution as LDs nucleation indicated: (1) the nucleation, which preferred at or by IDs intersections, is attributed to the flexible movement of atomic steps, by which the line orientations of ID segments at intersections can be adaptively altered to be parallel to the traces of LDs glide planes; (2) the weakened block effect of main segments in low strain concentrations is responsible for the unexpected nucleation across main segments in a direction which largely deviates from main segments. This investigation gives helpful understanding of the interface-mediated deformation in not only Zr/Nb but also other hcp/bcc (especially hcp crystals with low c/a ratios) nanolayered composites, and can satisfy the renewed interest in the fundamental scientific field of dislocations-interfaces interactions.

中文翻译：

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Zr-Nb双金属界面的位错成核与界面位错的动态演化相配合

摘要 双金属界面晶格位错 (LD) 的成核对于纳米级多层金属复合材料的界面介导变形和强化机制至关重要。这种成核不仅取决于外部载荷，而且还与界面位错 (ID) 网络及其动态演化密切相关。在这项研究中，我们专注于 LD 成核与遵循 Pitch-Schrader 和 Burgers 取向关系的 Zr/Nb 双金属界面的 ID 动态演化合作。为了在分子动力学模拟中模拟 Zr 和 Nb 原子之间的交叉相互作用，开发了一种经验嵌入原子方法潜力。采用自动 Nye 张量分析方法直接识别 ID 的特征，结果表明：（1）具有明显方向性的多个片段，命名的主要部分，定期分布在 ID 网络中；(2) 主要部分在 ID 相互交叉的区域通过几个原子步骤连接。这些特性首次展示了 hcp/bcc 接口的重要细节。作为LDs成核的IDs动态演化的进一步分析表明：（1）在IDs相交处或通过IDs相交处优选的成核归因于原子步骤的灵活运动，由此可以自适应地改变相交处ID段的线方向平行于 LD 滑翔面的轨迹；(2) 在低应变集中，主链段的块效应减弱是主链段在很大程度上偏离主链段的方向上意外成核的原因。