Chen S H, Chan K C, Wang G, Wu F F, Xia L, Ren J L, Li J, Dahmen K A, Liaw P K
Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Laboratory for Microstructures, Shanghai University, Shanghai 200444, China.
Sci Rep. 2016 Feb 25;6:21967. doi: 10.1038/srep21967.
The plastic flow of bulk metallic glasses (BMGs) is characterized by intermittent bursts of avalanches, and this trend results in disastrous failures of BMGs. In the present work, a double-side-notched BMG specimen is designed, which exhibits chaotic plastic flows consisting of several catastrophic avalanches under the applied loading. The disastrous shear avalanches have, then, been delayed by forming a stable plastic-flow stage in the specimens with tailored distances between the bottoms of the notches, where the distribution of a complex stress field is acquired. Differing from the conventional compressive testing results, such a delaying process is independent of loading rate. The statistical analysis shows that in the specimens with delayed catastrophic failures, the plastic flow can evolve to a critical dynamics, making the catastrophic failure more predictable than the ones with chaotic plastic flows. The findings are of significance in understanding the plastic-flow mechanisms in BMGs and controlling the avalanches in relating solids.
大块金属玻璃（BMG）的塑性流动以间歇性的雪崩式爆发为特征，这种趋势会导致BMG发生灾难性失效。在本研究中，设计了一种双侧缺口BMG试样，该试样在施加载荷下呈现出由几次灾难性雪崩组成的混沌塑性流动。通过在缺口底部之间设置特定距离的试样中形成稳定的塑性流动阶段，灾难性的剪切雪崩得以延迟，在此过程中获得了复杂应力场的分布。与传统压缩试验结果不同，这种延迟过程与加载速率无关。统计分析表明，在具有延迟灾难性失效的试样中，塑性流动可以演化为临界动力学，使得灾难性失效比具有混沌塑性流动的情况更具可预测性。这些发现对于理解BMG中的塑性流动机制以及控制相关固体中的雪崩具有重要意义。
