Size effects on tensile and compressive strengths in metallic glass nanowires
Size effects on tensile and compressive strengths in metallic glass nanowires
复制标题
尺寸对金属玻璃纳米线拉伸和压缩强度的影响
DOI：
10.1016/j.jmps.2015.07.018
复制
发表时间：
2015-11
影响因子：
5.3
通讯作者：
Chen Changqing
中科院分区：
文献类型：
--
作者：
Zhou Xiaoling;Zhou Haofei;Li Xiaoyan;Chen Changqing
剪切局部脆性是金属玻璃的主要缺陷，制约了其实际应用。先前的实验提供了如何通过将金属玻璃的样品尺寸减小到100纳米量级来抑制剪切局部化的见解。为了在更精细的尺度上揭示金属玻璃的尺寸效应和相关的变形机制，我们对金属玻璃纳米线的单轴压缩和拉伸进行了大规模的原子模拟。仿真结果表明，随着金属玻璃试样直径从45 nm减小到8 nm，试样的抗拉屈服强度增大，抗压屈服强度减小；所有模拟金属玻璃试样均以均匀流动为控制变形机制，塑性剪切倾向于从试样表面开始并向内部扩散。为了合理化屈服强度的尺寸依赖性，我们提出了基于表面应力和Mohr-Coulomb准则的理论模型。理论预测与模拟结果吻合较好，表明表面应力对mg在100 nm以下的屈服有重要作用。最后，讨论了不同长度尺度下金属玻璃强度的尺寸效应。我们的研究结果表明，剪切能带能量和表面应力可能是决定mggs从剪切局部化到均匀变形过渡所需的临界尺寸的两个关键参数。
Shear localization induced brittleness is the main drawback of metallic glasses which restricts their practical applications. Previous experiments have provided insights on how to suppress shear localization by reducing the sample size of metallic glasses to the order of 100 nm. In order to reveal the size effects and associated deformation mechanisms of metallic glasses in an even finer scale, we perform large-scale atomistic simulations for the uniaxial compression and tension of metallic glass nanowires. The simulation results show that, as the diameter of metallic glass samples decreases from 45 nm to 8 nm, the tensile yield strength increases while the compressive yield strength decreases. Homogeneous flow is observed as the governing deformation mechanism in all simulated metallic glass samples, where plastic shearing tends to initiate on the sample surface and propagate into the interior. To rationalize the size dependence of yield strengths, we propose a theoretical model based on the concept of surface stress and Mohr–Coulomb criterion. The theoretical predictions agree well with the simulation results, implying the important role of surface stress on the yielding of MGs below 100 nm. Finally, a discussion about the size effects of strength in metallic glasses at different length scales is provided. Our results suggest that the shear band energy and surface stress might be the two crucial parameters in determining the critical size required for the transition from shear localization to homogeneous deformation in MGs.
登录
查看更多内容
影响因子：
19
作者：
Kim, Ju-Young;Jang, Dongchan;Greer, Julia R.
通讯作者：
Greer, Julia R.
CuZrAl 大块金属玻璃的泊松比和塑性
DOI：
10.1016/j.msea.2007.07.062
发表时间：
2008-06
影响因子：
6.4
作者：
Bai, H. Y.;Yu, Peng
通讯作者：
Yu, Peng
影响因子：
1.2
作者：
C. Chen;Y. Pei;J. Hosson
通讯作者：
C. Chen;Y. Pei;J. Hosson
影响因子：
8.6
作者：
Z. Zhang;G. He;J. Eckert;L. Schultz
通讯作者：
Z. Zhang;G. He;J. Eckert;L. Schultz
使用左手材料的后向耦合波导耦合器
影响因子：
4
作者：
Chen, HS;Yuan, Y;Grzegorczyk, TM;Ran, LX;Kong, A;Huangfu, JT
通讯作者：
Huangfu, JT