Compression testing of metallic glass at small length scales: Effects on deformation mode and stability
Compression testing of metallic glass at small length scales: Effects on deformation mode and stability
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DOI：
10.1016/j.actamat.2010.06.054
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发表时间：
2010-10-01
期刊：
影响因子：
9.4
通讯作者：
Flores, Katharine M.
中科院分区：
文献类型：
--
作者：
Bharathula, Ashwini;Lee, Seok-Woo;Flores, Katharine M.
采用直径为200 nm ~ 3.6 μ m的微压缩试样研究了Zr基大块非晶合金塑性变形的尺寸效应。剪切带被证明是更稳定的，在这个长度尺度比在宏观尺度的测试，因为一个较小的样本负载框架刚度比。在直径小于300 nm的试样中，在低应变下观察到从离散应变突发到更连续变形（包括局部化和非局部化贡献）的变形模式的变化。应变破裂的大小与试样直径之间呈线性关系。从个别流动缺陷，与观察到的行为一致的应变的叠加模型，提出。此数据的外推表明，一个临界剪切带核长度为11纳米是成功的流动本地化所需的。这一极限对于强化和韧化策略的发展具有重要意义。(C)2010 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Size effects on plastic deformation of a Zr-based bulk metallic glass were examined using microcompression specimens with diameters ranging from 200 nm to 3.6 mu m. Shear banding is shown to be more stable at this length scale than in macro-scale testing because of a smaller specimen to load frame stiffness ratio. A change in deformation mode from discrete strain bursts to more continuous deformation including both localized and non-localized contributions was observed at low strains in specimens less than 300 nm in diameter. A linear relationship was observed between the magnitude of the strain burst and the specimen diameter. A model for the superposition of strain from individual flow defects, consistent with the observed behavior, is presented. Extrapolation of this data indicates that a critical shear band nucleus length of 11 nm is required for successful flow localization. This limit has important implications for the development of strengthening and toughening strategies. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.