The dynamics of shear band propagation in metallic glasses
The dynamics of shear band propagation in metallic glasses
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DOI：
10.1016/j.actamat.2023.118787
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发表时间：
2023-02-28
期刊：
影响因子：
9.4
通讯作者：
Deng，Binghui
中科院分区：
文献类型：
--
作者：
Luo，Jian;Huang，Liping;Deng，Binghui
由于实验中可获得的时间和空间尺度有限，理解金属玻璃中剪切带传播的动力学仍然是难以捉摸的。在微观尺度上对两种模型金属玻璃进行了分子动力学模拟，研究了在宏观应变为3- 5%的单轴拉伸条件下主导剪切带的扩展。对于这两种材料，剪切带可以是传播速度超过它们各自的剪切波速度的intersonic。传播表现出内在的不稳定性，表现为微分支和相当大的波动速度。剪切带尖端前的剪切应变奇异性与宏观拉伸应变无关，与距尖端的距离成1/r关系。此外，我们还研究了单轴拉伸下两个剪切带的相交，在此过程中，观察到了路径偏转、速度减慢和交界区的温度升高。剪切带扩展的动力学表明，在弱非线性断裂力学理论框架下，金属玻璃中的剪切带可以看作是剪切裂纹。
Understanding the dynamics of shear band propagation in metallic glasses remains elusive due to the limited temporal and spatial scales accessible in experiments. In micron-scale molecular dynamics simulations on two model metallic glasses, we studied the propagation of a dominant shear band under uniaxial tension with a macroscopic strain of 3-5%. For both materials, the shear band can be intersonic with a propagation speed exceeding their respective shear wave speeds. The propagation exhibits intrinsic instability that manifests itself as microbranching and considerable fluctuations in velocity. The shear strain singularity ahead of propagating shear band tip scales as 1/r(ris the distance away from the tip), independent of the macroscopic tensile strain. In addition, we studied the intersection of two shear bands under uniaxial tension, during which path deflection, speed slowing-down, and temperature rise at the junction region were observed. The dynamics of propagating shear band shown here indicate that shear band in metallic glasses can be viewed as shear crack under the framework of weakly nonlinear fracture mechanics theory.