Medium-range ordering, structural heterogeneity, and their influence on properties of Zr-Cu-Co-Al metallic glasses
Medium-range ordering, structural heterogeneity, and their influence on properties of Zr-Cu-Co-Al metallic glasses
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DOI：
10.1103/physrevmaterials.5.115604
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发表时间：
2021-11-15
影响因子：
3.4
通讯作者：
Hwang, Jinwoo
中科院分区：
文献类型：
--
作者：
Im, Soohyun;Wang, Yuchi;Hwang, Jinwoo
对 Zr-Cu-Co-Al 金属玻璃 (MG) 中的中程有序 (MRO) 和结构异质性进行了表征，并研究了它们对延展性的影响。使用四维扫描透射电子显微镜获得的纳米衍射图案的暗场图像的角相关分析和数字重建揭示了位于纳米尺度的MRO区域的结构对称性及其尺寸分布。 MRO 区域的类型和尺寸分布随着 MG 成分的变化而变化，一些 MRO 类型明显类似于已知金属间相的对称性。当成分异质性增加时，MRO 似乎在结构上变得更加受挫（例如，缺乏六重对称性），这可能与观察到的延展性增加有内在联系。基于这一假设，结合实验获得的 MRO 信息（类型和尺寸）进行中尺度变形模拟，以深入了解潜在的 MRO-延展性关系。假设不同类型的MRO具有不同的属性，并通过参数化研究了它们对应力-应变曲线、最大连通自由体积和极值应变值点总数的影响。模拟结果表明，MRO 结构在类型和尺寸方面的异质性程度与 MG 的延展性直接相关。
Medium-range ordering (MRO) and structural heterogeneity in Zr-Cu-Co-Al metallic glasses (MGs) are characterized and their influence on ductility is investigated. Angular correlation analysis and digital reconstruction of dark-field images of nanodiffraction patterns acquired using four-dimensional scanning transmission electron microscopy reveal structural symmetries of the MRO regions localized at the nanometer scale, as well as their size distribution. The type and size distribution of the MRO regions change as a function of MG composition, with some MRO types clearly resembling the symmetry of known intermetallic phases. The MRO appears to become more structurally frustrated (e.g., lack of sixfold symmetry) when compositional heterogeneity increases, which may be inherently connected to the observed increase in ductility. Based on this hypothesis, mesoscale deformation simulations incorporating the experimentally acquired MRO information (types and sizes) are performed to gain insights on potential MRO-ductility relationship. Different types of MRO are assumed to have different properties and their influences on the stress-strain curve, the largest connected-free-volume, and the total number of extreme strain value sites are investigated parametrically. The simulation results reveal that the degree of heterogeneity in the MRO structures, in terms of both type and size, correlates directly with the ductility of the MGs.