A search for evidence of strain gradient hardening in Au submicron pillars under uniaxial compression using synchrotron X-ray micro diffraction
A search for evidence of strain gradient hardening in Au submicron pillars under uniaxial compression using synchrotron X-ray micro diffraction
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DOI：
10.1016/j.actamat.2007.10.031
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发表时间：
2008-02-01
期刊：
影响因子：
9.4
通讯作者：
Nix, W. D.
中科院分区：
文献类型：
--
作者：
Budiman, A. S.;Han, S. M.;Nix, W. D.
当晶体材料在小体积中机械变形时，塑性流动需要更高的应力。这被称为“小而强”的现象，并已被广泛观察到。已经提出了各种尺寸相关的强化机制来解释这种效应，通常涉及应变梯度。在这里，我们报告的搜索应变梯度作为一个可能的来源的强度进行均匀压缩的单晶亚微米柱的黄金，使用亚微米白光（巷）X射线衍射技术。我们已经发现，无论是单轴压缩之前和之后，没有证据表明，无论是显着的晶格曲率或亚晶粒结构。即使在变形过程中达到35%的应变和300 MPa的高流动应力后，情况也是如此。这些观察结果表明，这里的塑性不是由应变梯度或子结构硬化控制的，而是由位错源饥饿控制的，其中较小的体积更强，因为可用的位错源较少。(C)2007 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
When crystalline materials are mechanically deformed in small volumes, higher stresses are needed for plastic flow. This has been called the "smaller is stronger" phenomenon and has been widely observed. Various size-dependent strengthening mechanisms have been proposed to account for such effects, often involving strain gradients. Here we report on a search for strain gradients as a possible source of strength for single-crystal submicron pillars of gold subjected to uniform compression, using a submicron white-beam (Lane) X-ray diffraction technique. We have found, both before and after uniaxial compression, no evidence of either significant lattice curvature or subgrain structure. This is true even after 35% strain and a high flow stress of 300 MPa were achieved during deformation. These observations suggest that plasticity here is not controlled by strain gradients or substructure hardening, but rather by dislocation source starvation, wherein smaller volumes are stronger because fewer sources of dislocations are available. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.