State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
Institute of Structural Mechanics, Bauhaus-Universität Weimar, Weimar D-99425, Germany.
Phys Chem Chem Phys. 2018 Nov 7;20(41):26552-26557. doi: 10.1039/c8cp05557b. Epub 2018 Oct 11.
Compressive strength and deformation characteristics of a metallic glassy alloy related to strain rate are studied by molecular dynamics simulations. The negative strain rate dependency of strength is presented, i.e., compressive strength decreases with the increase of strain rate, which is well in line with the experimental results. The negative strain rate dependency of strength is explained from two aspects at the atomic scale of free volume and potential energy. Compressive strength is related to the free volume formation in a shear band, which is different from that in a metallic glass matrix. In addition, the relation of potential energy and temperature is also investigated, which indicates that thermal softening also plays an important role in the negative strain rate dependency of strength. The thermal-mechanical coupling mechanisms causing the negative strain rate dependency of the strength of the metallic glassy alloy are clarified. It is significant to explore the intrinsic deformation characteristics of the metallic glassy alloy under a high rate loading.
通过分子动力学模拟研究了与应变速率相关的金属玻璃合金的抗压强度和变形特性。研究表明，抗压强度具有负应变速率依赖性，即抗压强度随应变速率的增加而降低，这与实验结果吻合较好。从自由体积和势能的原子尺度两方面解释了强度的负应变速率依赖性。抗压强度与剪切带中自由体积的形成有关，这与金属玻璃基质中的自由体积形成不同。此外，还研究了势能与温度的关系，表明热软化在强度的负应变速率依赖性中也起着重要作用。阐明了导致金属玻璃合金强度负应变速率依赖性的热-机耦合机制。探索金属玻璃合金在高速加载下的内在变形特性具有重要意义。
