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Breakdown of the Stokes–Einstein relationship and rapid structural ordering in CuZrAl metallic glass-forming liquids
The Journal of Chemical Physics ( IF 4.4 ) Pub Date : 2021-09-08 , DOI: 10.1063/5.0062724
F Z Chen 1 , N A Mauro 2 , S M Bertrand 2 , P McGrath 2 , L Zimmer 2 , K F Kelton 1
Affiliation  

The results of a combined structural and dynamical study of Cu–Zr–Al metallic glass forming liquids are presented. Containerless high-energy x-ray scattering experiments made using electrostatic levitation are combined with molecular dynamics simulations to probe the onset of rapid structural ordering as well as the temperature-dependent diffusivity and viscosity in three liquids: Cu49Zr45Al6, Cu47Zr45Al8, and Cu43Zr45Al12. These compositions were chosen because they are reported to have dramatically different glass forming-ability. Experimental data show that the first peak in the x-ray static structure factor displays evidence for a Curie–Weiss type behavior, but also a peak in the effective Curie temperature. The evidence provided here for the onset of cooperativity, marked by a crossover temperature, TA (which is usually above the liquidus temperature), is accompanied by the onset of development of more spatially extended structural order in the liquids. Based on the molecular dynamics simulations, each of the liquids exhibits a clear breakdown of the Stokes–Einstein relation at a temperature near, but below, the crossover temperature, TA. The breakdown is manifest as a rapid reduction in the relative diffusion coefficients between Cu, Zr, and Al.

中文翻译:

斯托克斯-爱因斯坦关系的分解和 CuZrAl 金属玻璃形成液体中的快速结构排序

介绍了 Cu-Zr-Al 金属玻璃成型液的结构和动力学组合研究结果。使用静电悬浮进行的无容器高能 X 射线散射实验与分子动力学模拟相结合,以探测三种液体中快速结构有序的开始以及温度相关的扩散率和粘度:Cu 49 Zr 45 Al 6、Cu 47 Zr 45 Al 8和Cu 43 Zr 45 Al 12. 选择这些组合物是因为据报道它们具有显着不同的玻璃成型能力。实验数据表明,X 射线静态结构因子中的第一个峰显示了居里-魏斯型行为的证据,但也是有效居里温度的一个峰。这里提供的协同性开始的证据,以交叉温度T A(通常高于液相线温度)为标志,伴随着液体中更多空间扩展结构秩序的发展。根据分子动力学模拟,在接近但低于交叉温度T A 的温度下,每种液体都表现出明显的斯托克斯-爱因斯坦关系分解. 击穿表现为 Cu、Zr 和 Al 之间的相对扩散系数迅速降低。
更新日期:2021-09-15
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