Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
Department of Materials Science, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
J Chem Phys. 2019 Mar 21;150(11):111104. doi: 10.1063/1.5088184.
Solid materials, whether crystalline or glasses, are characterized by their elasticity. Generally, elasticity is independent of the probing strain if it is not exceeding the yielding point. Here, by contrast, we experimentally capture a pronounced strain-dependent elasticity in metallic glasses, as manifested by nonlinear mechanical damping in the apparent elastic deformation regime (∼1/100 of the yielding strain). Normal damping behaviors recover at higher temperatures but still below the glass transition. Atomistic simulations reproduce these features and reveal that they could be related to avalanche-like local structural instabilities. Our findings demonstrate that the standard elasticity is not held for metallic glasses at low temperatures and plastic events can be triggered at small perturbations. These results are consistent with previous simulations of model glasses and a scenario of hierarchical free-energy landscape of mean-field theory.
固态物质，无论是晶体还是玻璃，都具有弹性。一般来说，如果探测应变不超过屈服点，弹性是与应变无关的。相比之下，我们在这里通过实验在金属玻璃中捕捉到了明显的应变依赖性弹性，这表现为在明显的弹性变形区域（约为屈服应变的 1/100）中存在非线性机械阻尼。在更高的温度下，正常的阻尼行为会恢复，但仍低于玻璃化转变温度。原子模拟再现了这些特征，并表明它们可能与类似雪崩的局部结构不稳定性有关。我们的发现表明，在低温下，标准弹性不适用于金属玻璃，并且在小扰动下可能会引发塑性事件。这些结果与模型玻璃的先前模拟以及平均场理论的层次化自由能景观的情景一致。
