Dislocation multiplication mechanisms – Glissile junctions and their role on the plastic deformation at the microscale
Dislocation multiplication mechanisms – Glissile junctions and their role on the plastic deformation at the microscale
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DOI：
10.1016/j.actamat.2015.07.073
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发表时间：
2015-10
期刊：
影响因子：
9.4
通讯作者：
M. Stricker;D. Weygand
中科院分区：
文献类型：
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作者：
M. Stricker;D. Weygand
位错结被认为控制了晶体材料在塑性变形过程中的硬化行为。基于离散位错动力学模拟结果，研究了滑动结对微尺度样品塑性变形的影响。结果表明，随着位错密度ρ的增加、样品尺寸d的增大(可塌缩为一个无量纲参数dρ)以及由于全球晶体取向不同而激活的滑移系越来越多，滑移结的形成频繁且容易弯曲，成为有效的源。由此产生的新位错是可移动的，对宏观塑性变形的贡献率约为30%-60%。在尺寸为0.5~2μm，位错密度在10 12~10 14 m-2范围内，滑移结是产生可移动位错密度的重要来源。此外，还发现应力降与来自滑动结的位错活动之间存在显着的相关性。提出了一个速率公式，将这些发现包含在晶体塑性或连续体位错密度框架中。
Dislocation junctions are considered to control the hardening behavior of crystalline materials during plastic deformation. Here the influence of the glissile junction on the plastic deformation of microscale samples is investigated, based on discrete dislocation dynamics simulation results. It is found that with increasing dislocation density ρ, sample size d, which can be collapsed into a single dimensionless parameter d ρ, and an increasing number of activated slip systems due to different global crystallographic orientations, the glissile junction forms frequently and can bow out easily, acting as an effective source. The resulting new dislocations are mobile and contribute to the macroscopic plastic deformation on the order of 30–60%. In the size regime from 0.5 to 2 μm and dislocation densities in the range of 10 12–10 14 m-2, the glissile junction is therefore an important source for generating mobile dislocation density. Furthermore a significant correlation between stress drops and activity of dislocations originating from glissile junctions is found. A rate formulation is proposed to include these findings in crystal plasticity or continuum dislocation density frameworks.