On the similitude relation for dislocation wall thickness under cyclic deformation
On the similitude relation for dislocation wall thickness under cyclic deformation
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DOI：
10.1016/j.msea.2022.142972
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Farhan Ashraf;G. Castelluccio
中科院分区：
文献类型：
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作者：
Farhan Ashraf;G. Castelluccio
位错亚结构已被广泛的特点，以解释应变硬化的起源。高位错密度的区域（壁）限制了移动的位错在低位错密度的区域（沟道）中的滑动。透射电子显微镜（TEM）已经表明，壁之间的距离与流动应力成反比，这通常被称为相似原理。然而，它仍然不清楚是否存在相似标度律的位错壁厚或壁分数。理解这样的比例律有助于支持基于亚结构的晶体塑性，验证位错动力学模型，并解释亚结构的形成过程。因此，这项工作调查TEM图像从各种FCC金属材料在不同温度下的循环变形，以评估位错壁的相似原理的存在。结果表明，壁厚确实遵循相似，但比例常数依赖于某些结构的温度。
Dislocation substructures have been extensively characterized to explain the origin of strain hardening. Regions of high dislocation densities (walls) constrain the glide of mobile dislocations in regions of lower dislocation density (channels). Transmission electron microscopy (TEM) has shown that the distance in between walls is inversely proportional to flow stress, which is often referred as to the similitude principle. However, it still remains unclear whether a similitude scaling law exists for the dislocation wall thickness or wall fraction. The understanding of such a scaling law is instrumental to support substructure-based crystal plasticity, validate dislocation dynamics models, and explain substructure formation processes. Hence, this work surveys TEM images from various FCC metallic materials under cyclic deformation at various temperatures to assess the existence of the similitude principle for dislocation walls. The results demonstrate that the wall thickness does follow similitude, but the proportionality constant depends on the temperature for some structures.