Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Nat Commun. 2014 Dec 15;5:5823. doi: 10.1038/ncomms6823.
For glasses, the structural origin of their flow phenomena, such as elastic and plastic deformations especially the microscopic hidden flow before yield and glass-to-liquid transition (GLT), is unclear yet due to the lack of structural information. Here we investigate the evolution of the microscopic localized flow during GLT in a prototypical metallic glass combining with dynamical mechanical relaxations, temperature-dependent tensile experiments and stress relaxation spectra. We show that the unstable and high mobility nano-scale liquid-like regions acting as flow units persist in the glass and can be activated by either temperature or external stress. The activation of such flow units is initially reversible and correlated with β-relaxation. As the proportion of the flow units reaches a critical percolation value, a mechanical brittle-to-ductile transition or macroscopic GLT happens. A comprehensive picture on the hidden flow as well as its correlation with deformation maps and relaxation spectrum is proposed.
对于眼镜，由于缺乏结构信息，其流动现象的结构起源，如弹性和塑性变形，尤其是屈服前和玻璃-液体转变 (GLT) 的微观隐藏流动，尚不清楚。在这里，我们结合动态力学松弛、温度相关拉伸实验和应力松弛谱，研究了在典型金属玻璃中 GLT 期间微观局部流动的演化。我们表明，在玻璃中作为流动单元的不稳定和高迁移率纳米尺度液态区域可以通过温度或外部应力来激活。这种流动单元的激活最初是可逆的，并与 β-松弛相关。随着流动单元的比例达到临界渗流值，力学脆性到韧性的转变或宏观 GLT 就会发生。提出了关于隐藏流动的综合图景，以及它与变形图谱和弛豫谱的相关性。
