Nguyen Duc, Zhu Zhi-Guang, Pringle Brian, Lyding Joseph, Wang Wei-Hua, Gruebele Martin
Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA.
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Phys Chem Chem Phys. 2016 Jun 22;18(25):16856-61. doi: 10.1039/c6cp02654k.
Glassy metallic alloys are richly tunable model systems for surface glassy dynamics. Here we study the correlation between atomic mobility, and the hopping rate of surface regions (clusters) that rearrange collectively on a minute to hour time scale. Increasing the proportion of low-mobility copper atoms in La-Ni-Al-Cu alloys reduces the cluster hopping rate, thus establishing a microscopic connection between atomic mobility and dynamics of collective rearrangements at a glass surface made from freshly exposed bulk glass. One composition, La60Ni15Al15Cu10, has a surface resistant to re-crystallization after three heating cycles. When thermally cycled, surface clusters grow in size from about 5 glass-forming units to about 8 glass-forming units, evidence of surface aging without crystal formation, although its bulk clearly forms larger crystalline domains. Such kinetically stable glass surfaces may be of use in applications where glassy coatings stable against heating are needed.
玻璃态金属合金是用于表面玻璃态动力学的高度可调节模型系统。在此，我们研究了原子迁移率与表面区域（团簇）的跳跃速率之间的相关性，这些表面区域在分钟到小时的时间尺度上集体重排。增加La-Ni-Al-Cu合金中低迁移率铜原子的比例会降低团簇跳跃速率，从而在原子迁移率与由新暴露的块状玻璃制成的玻璃表面集体重排动力学之间建立微观联系。一种成分La60Ni15Al15Cu10，在三个加热循环后具有抗再结晶的表面。当进行热循环时，表面团簇的尺寸从约5个玻璃形成单元增长到约8个玻璃形成单元，这是表面老化而无晶体形成的证据，尽管其块状明显形成更大的晶域。这种动力学稳定的玻璃表面可能在需要抗加热稳定的玻璃涂层的应用中有用。
