Dislocation mechanisms in the plastic deformation of monodisperse wet foams within an expansion–contraction microfluidic geometry
Dislocation mechanisms in the plastic deformation of monodisperse wet foams within an expansion–contraction microfluidic geometry
复制标题
膨胀收缩微流体几何结构中单分散湿泡沫塑性变形的位错机制
DOI：
10.1039/c9sm00477g
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发表时间：
2019
期刊：
影响因子：
3.4
通讯作者：
Biswal, Sibani Lisa
中科院分区：
文献类型：
--
作者：
Vecchiolla, Daniel;Biswal, Sibani Lisa
密集堆积的湿泡沫在宽 (1400–1800 μm) 微流体通道中逐渐膨胀和收缩，以研究单分散气泡基质内的局部塑性变形事件。在一定范围的流体流速和气泡堆积密度下，观察到了由拉伸应力和压缩应力引起的位错滑移、反射、成核和偶极子转变。不同的循环反射发生在流动泡沫的两个独立区域中，并且扩展了张力下位错反射的机制。由于通道内相应的流线，不对称通道的使用在模型晶体系统中产生了直的、对齐的气泡行和弯曲的、未对齐的行之间的二分法。由此产生的晶体排列梯度对位错迁移率和塑性变形有许多影响。发现 7/7 偶极子在解离前重新排列成与泡沫流一致的更稳定的结构。发现由 5/5 偶极子组成的位错（类似于碳纳米结构中的逆斯通-威尔士缺陷）通过中间环结构相互传递，中间环结构最常见的是由围绕三角形中心气泡的三个位错对组成。
Densely packed wet foam was subjected to gradual expansion and contraction in a wide (1400–1800 μm) microfluidic channel to study localized plastic deformation events within the monodisperse bubble matrix. Dislocation glide, reflection, nucleation, and dipole transformations from extensional and compressive stresses were observed across a range of fluid flow rates and bubble packing densities. Disparate, cyclic reflections occur in two independent regions of the flowing foam, and the mechanisms of dislocation reflection under tension are expanded. The use of an asymmetric channel created a dichotomy in the model crystalline system between straighter, aligned bubble rows and curved, misaligned rows due to the corresponding streamlines within the channel. The resulting gradient in crystalline alignment had numerous effects on dislocation mobility and plastic deformation. 7/7 dipoles were found to rearrange to a more stable configuration aligned with the foam flow before dissociating. Dislocations comprising 5/5 dipoles (resembling the inverse-Stone–Wales defect in carbon nanostructures) were discovered to pass through one another via intermediate ring structures, which most commonly consisted of three dislocation pairs around a triangular-shaped central bubble.