Dislocation avalanches, strain bursts, and the problem of plastic forming at the micrometer scale
Dislocation avalanches, strain bursts, and the problem of plastic forming at the micrometer scale
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DOI：
10.1126/science.1143719
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发表时间：
2007-10-12
期刊：
影响因子：
56.9
通讯作者：
Zapperi, Stefano
中科院分区：
文献类型：
--
作者：
Csikor, Ferenc F.;Motz, Christian;Zapperi, Stefano
在应力下，许多晶体材料表现出由晶格位错运动引起的不可逆塑性变形。在塑性变形的微晶中，内部位错雪崩导致应力-应变曲线的跳跃（应变爆发），而在宏观样品中，塑性表现为一个平滑的过程。通过结合三维模拟的动力学相互作用的位错与相应的变形行为的统计分析，我们确定了分布的应变变化过程中的位错雪崩，并建立其依赖于微晶尺寸。我们的研究结果表明，对于微米和亚微米尺度上的样品尺寸，大的应变波动可能会使其难以控制在塑性成形过程中产生的形状。
Under stress, many crystalline materials exhibit irreversible plastic deformation caused by the motion of lattice dislocations. In plastically deformed microcrystals, internal dislocation avalanches lead to jumps in the stress-strain curves (strain bursts), whereas in macroscopic samples plasticity appears as a smooth process. By combining three-dimensional simulations of the dynamics of interacting dislocations with statistical analysis of the corresponding deformation behavior, we determined the distribution of strain changes during dislocation avalanches and established its dependence on microcrystal size. Our results suggest that for sample dimensions on the micrometer and submicrometer scale, large strain fluctuations may make it difficult to control the resulting shape in a plastic-forming process.