Lu Yunzhuo, Zhang Zhihua, Lu Xing, Qin Zuoxiang, Shen Jun, Huang Yongjiang, Liaw Peter K
School of Materials Science and Engineering, Dalian Jiaotong University, Dalian, 116028, People's Republic of China.
School of Materials Science and Engineering, Tongji University, Shanghai, 201804, People's Republic of China.
Sci Rep. 2017 Dec 4;7(1):16882. doi: 10.1038/s41598-017-17271-8.
Contrary to crystalline solids, amorphous solids always become softer when vitrifying the melts under higher cooling rates. Understanding this phenomenon is of utmost importance in providing a basis for the mechanical-performance control of amorphous solids. However, the underlying mechanisms leading to this cooling-rate-induced softening of amorphous solids have remained elusive, especially the dynamic reasons are neglected. Here, we use a colloidal glass as the model system to directly study this issue. Shear modulus is used as the representative parameter to monitor the stress-bearing properties of colloidal glass. The space-spanning immobile particles, whose population is sensitive to the cooling rate, are found to make the dominant contribution to the shear modulus. The rapid solidification induced softening of colloidal glass is observed to originate from fewer immobile particles formed at higher cooling rates.
与晶体固体相反，非晶态固体在更高冷却速率下使熔体玻璃化时总是会变得更软。理解这一现象对于为非晶态固体的机械性能控制提供基础至关重要。然而，导致非晶态固体这种冷却速率诱导软化的潜在机制仍然难以捉摸，尤其是动力学原因被忽视了。在这里，我们使用胶体玻璃作为模型系统来直接研究这个问题。剪切模量用作监测胶体玻璃承载特性的代表性参数。发现空间跨度的固定颗粒对剪切模量起主要作用，其数量对冷却速率敏感。观察到胶体玻璃的快速凝固诱导软化源于在更高冷却速率下形成的固定颗粒较少。
