Yielding and shear banding of metallic glasses
Yielding and shear banding of metallic glasses
复制标题
DOI：
10.1016/j.actamat.2013.06.025
复制
发表时间：
2013-09-01
期刊：
影响因子：
9.4
通讯作者：
Liu, C. T.
中科院分区：
文献类型：
--
作者：
Liu, Z. Y.;Yang, Y.;Liu, C. T.
本研究通过精心设计的循环微压缩试验，研究了锆基、铜基、铁基和镁基金属玻璃的屈服和随后的剪切带状演化过程。结果表明，屈服始于一种稳定的塑性流动，其粘度约为10(12)PaS，类似于玻璃化转变。这提供了关键证据，表明屈服是由内部随机分布的类液体核心连接在一起的应力诱导的玻璃化转变引起的。在一个临界点，液化层穿透整个样品，起始粘度为10(8)PaS，与类液体岩心的起始粘度相当。沿类液层，剪切带的传播包括剪切带的滑动和剪切带的阻止。动态软化导致剪切带滑动速度的增加，从而产生剪切偏移量，这可以用线性软化模型成功地捕捉到。一旦剪切带中的弹性能量耗散，其内部结构开始恢复，类固体基质被重建，导致剪切带停滞。建立了一个简单的示意图，阐明了屈服和剪切带状动力学，揭示了磁致伸缩变形机制的基本性质。(C)2013 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
In this study the yielding and subsequent shear banding evolution process of Zr-, Cu-, Fe- and Mg-based metallic glasses (MGs) were investigated using carefully designed cyclic microcompression tests. It was found that yielding starts from a stable plastic flow with a viscosity of the order of 10(12) Pa s, resembling that of the glass transition. This provides critical evidence that yielding is caused by a stress-induced glass transition with internal randomly distributed liquid-like cores get connected. Up to a critical point the liquidized layer penetrates the entire sample with an initiation viscosity of 10(8) Pa s, comparable with that of the liquid-like cores. Along the liquid-like layer shear band propagation involves shear band sliding and is succeeded by shear band arrest. Dynamic softening leads to an increase in the velocity of shear band sliding, with resultant shear offset, which can be successfully captured by a linear softening model. Once the elastic energy in the shear band is dissipated its internal structure begins to recover, with the solid-like matrix being reconstructed, resulting in shear band arrest. A simple diagram elucidating the yielding and shear banding dynamics is constructed, which sheds light on the fundamental nature of the deformation mechanisms of MGs. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.