Determining the three-dimensional atomic structure of a metallic glass
Yao Yang, Jihan Zhou, Fan Zhu, Yakun Yuan, Dillan Chang, Dennis S. Kim, Minh Pham, Arjun Rana, Xuezeng Tian, Yonggang Yao, Stanley Osher, Andreas K. Schmid, Lia… 展开作者
Yao Yang, Jihan Zhou, Fan Zhu, Yakun Yuan, Dillan Chang, Dennis S. Kim, Minh Pham, Arjun Rana, Xuezeng Tian, Yonggang Yao, Stanley Osher, Andreas K. Schmid, Liangbing Hu, Peter Ercius, Jianwei Miao
Amorphous solids such as glass are ubiquitous in our daily life and have found broad applications ranging from window glass and solar cells to telecommunications and transformer cores. However, due to the lack of long-range order, the three-dimensional (3D) atomic structure of amorphous solids have thus far defied any direct experimental determination without model fitting. Here, using a multi-component metallic glass as a proof-of-principle, we advance atomic electron tomography to determine the 3D atomic positions in an amorphous solid for the first time. We quantitatively characterize the short-range order (SRO) and medium-range order (MRO) of the 3D atomic arrangement. We find that although the 3D atomic packing of the SRO is geometrically disordered, some SRO connect with each other to form crystal-like networks and give rise to MRO. We identify four crystal-like MRO networks - face-centred cubic, hexagonal close-packed, body-centered cubic and simple cubic - coexisting in the sample, which show translational but no orientational order. These observations confirm that the 3D atomic structure in some parts of the sample is consistent with the efficient cluster packing model. Looking forward, we anticipate this experiment will open the door to determining the 3D atomic coordinates of various amorphous solids, whose impact on non-crystalline solids may be comparable to the first 3D crystal structure solved by x-ray crystallography over a century ago.
Glasses are featured with a disordered amorphous structure, being opposite to crystals that are constituted by periodic lattices. In this study we report that the exceptional thermodynamic and kinetic stability of an ultra-stable binary ZrCu metallic glass, fabricated by high-temperature physical vapor deposition, originates from ubiquitous crystal-like medium range order (MRO) constituted by Voronoi polyhedron ordering with well-defined local translational symmetry beyond nearest atomic neighbors. The crystal-like MRO significantly improves the thermodynamic and kinetic stability of the glass…
Metallic glasses exhibit fast mechanical relaxations at temperatures well below the glass transition, one of which shows little variation with temperature known as nearly constant loss (NCL). Despite the important implications of this phenomenon to in aging and deformation, the origin of the relaxation is unclear. Through molecular dynamics simulations of a model metallic glass, Cu_64.5Zr_35.5, we implement dynamic mechanical analysis with system stress decomposed into atomic-level stresses to identify the group of atoms responsible for NCL. This work demonstrates that NCL relaxation is due to…
In the present investigation the glass forming ability of Ce65Al25Co10 metallic glass has been reported. It was successfully synthesised using melt spinning techniques. The existence of amorphous phase in Ce65Al25Co10 alloy have been proved using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The thermal analysis of the synthesised sample using differential scanning calorimetry (DSC) shows a glass transition around 371 K, thus confirms existence of glassy phase at room temperature. The hardness of the synthesised sample at different load have been demonstrated…
The Fractal Dimension of Interfaces in Edwards-Anderson and Long-range Ising Spin Glasses: Determining the Applicability of Different Theoretical Descriptions
Crystallization of metallic glass as a grain-boundary nucleated process: experimental and theoretical evidence for the grain structure of metallic glasses
Cycling of a metallic glass between ambient and cryogenic temperatures can induce higher-energy states characteristic of glass formation on faster cooling. This rejuvenation, unexpected because it occurs at small macroscopic strains and well below the temperatures of thermally induced structural change, is important, for example, in improving plasticity. Molecular-dynamics simulations elucidate the mechanisms by which thermal cycling can induce relaxation (reaching lower energy) as well as rejuvenation. Thermal cycling, over tens of cycles, drives local atomic rearrangements progressively eras…
The low-temperature quasi-universal behavior of amorphous solids has been attributed to the existence of spatially-localized tunneling defects found in the low-energy regions of the potential energy landscape. Computational models of glasses can be studied to elucidate the microscopic nature of these defects. Recent simulation work has demonstrated the means of generating stable glassy configurations for models that mimic metallic glasses using the swap Monte Carlo algorithm. Building on these studies, we present an extensive exploration of the glassy metabasins of the potential energy landsca…
An atomistic understanding of annealing embrittlement is a longstanding issue for metallic glasses, which is still lacking due to the insurmountable gap between the thermal history of atomic models and laboratory-made samples. Here, based on a thermal-cycling annealing method that can vary the effective quenching rate over ten orders of magnitude, we perform an atomistic study of the ductile-brittle transition in a ternary model metallic glass, which can be keyed to the annealing embrittlement in bulk metallic glasses. We reveal that thermal annealing can effectively obliterate thermally activ…
Transmutation-accelerated sampling method for multi-component ZrCu(Al) metallic glasses
NOMATEN Centre of Excellence, National Center for Nuclear Research(NOMATEN卓越中心,国家核研究中心);Univ. Lyon, INSA-Lyon, CNRS, LaMCoS, UMR 5259(里昂大学,里昂国立应用科学学院,法国国家科学研究中心,LaMCoS实验室);Laboratoire de Mécanique des Solides, CNRS, Ecole Polytechnique(固体力学实验室,法国国家科学研究中心,巴黎综合理工学院);Aalto University(阿尔托大学)
Using inelastic neutron scattering and molecular dynamics simulations on a model Zr-Cu-Al metallic glass, we show that transverse phonons persist well into the high-frequency regime, and can be detected at large momentum transfer. Furthermore, the apparent peak width of the transverse phonons was found to follow the static structure factor. The one-to-one correspondence, which was demonstrated for both Zr-Cu-Al metallic glass and a 3-dimensional Lennard-Jones model glass, suggests a universal correlation between the phonon dynamics and the underlying disordered structure. This remarkable corre…
Compressed correlation functions and fast aging dynamics in metallic glasses
我们提出的X射线光子相关光谱测量的原子动力学在Zr 67 Ni 33金属玻璃,远低于其玻璃化转变温度。我们发现密度涨落的衰减可以用压缩的、比指数快的关联函数来描述,这种关联函数可以用著名的Kohlrausch-Williams-Watts函数来模拟,其形状指数β大于1。这个参数还被发现是独立的等待时间和波矢量,导致的可能性,重新调整所有的关联函数到一个单一的主曲线。在玻璃态的动力学的特征还在于不同的老化制度,坚持在深玻璃态。这些功能似乎是普遍的金属玻璃,并建议一个非扩散性质的动态。这种普遍性是支持的可能性,描述的结构弛豫时间与等待时间的快速增加,使用一个独特的模型函数,独立的系统的微观细节。
NOMATEN Centre of Excellence, National Center for Nuclear Research(国家核研究中心 NOMATEN 卓越中心);Center for Complexity and Biosystems, Department of Physics "Aldo Pontremoli", University of Milan(米兰大学物理学院复杂性与生物系统中心);Saarland University, Chair of Metallic Materials(萨尔兰大学金属材料讲席);Glass and Time , IMFUFA, Department of Science and Environment, Roskilde University(罗斯基勒大学科学与环境学院 IMFUFA 玻璃与时间);Department of Materials Science, Montanuniversität Leoben(莱奥本矿业大学材料科学系);Erich Schmid Institute of Materials Science, Austrian Academy of Sciences(奥地利科学院埃里希·施密德材料科学研究所);Department of Materials Science and Engineering, Johns Hopkins University(约翰斯·霍普金斯大学材料科学与工程系);Department of Mechanical Engineering, Johns Hopkins University(约翰斯·霍普金斯大学机械工程系);Department of Physics and Astronomy, Johns Hopkins University(约翰斯·霍普金斯大学物理与天文学系);Hopkins Extreme Materials Institute, Johns Hopkins University(约翰斯·霍普金斯大学霍普金斯极端材料研究所);Technical University of Berlin, Chair of Metallic Materials(柏林工业大学金属材料讲席)
We theoretically investigate high-pressure effects on the atomic dynamics of metallic glasses. The theory predicts compression-induced rejuvenation and the resulting strain hardening that have been recently observed in metallic glasses. Structural relaxation under pressure is mainly governed by local cage dynamics. The external pressure restricts the dynamical constraints and slows down the atomic mobility. In addition, the compression induces a rejuvenated metastable state (local minimum) at a higher energy in the free energy landscape. Thus, compressed metallic glasses can rejuvenate and the…
The first report of phase separation in metallic glass has attracted significant attention due to their unique micro-structural variations of amorphous phases at different domain size. In the continuation of this the view is to understanding the genesis of phase separation in Ce based metallic glass. In this paper, we present extensive investigations with particular reference to low concentration of Ga in Ce-Al-Ga metallic glass. Micro-structural characteristics and indentation behavior of melt spun Ce75Al25-xGax metallic glass has been investigated by X-ray diffraction (XRD) and Transmission …
The first metallic glass of Au-Si alloy has been discovered for over half a century, but its atomic structure is still puzzling. Herein, Au 8 Si dodecahedrons with local five-fold symmetry are revealed as building blocks in Au-Si metallic glass, and the interconnection modes of Au 8 Si dodecahedrons determine the medium-range order. With dimensionality reduction, the surface ordering is attributed to the motif transformation of Au 8 Si dodecahedrons into planar Au 5 Si pyramids with five-fold symmetry, and thus the self-assembly of Au 5 Si pyramids leads to the formation of the ordered Au 2 Si…
What renders bulk metallic glass ductile/brittle? -- new insight from the medium-range order
要理解整体大块金属玻璃(BMG)的延展性或脆性,需要对非晶结构有详细的了解。在缺口三点弯曲试验之前和之后,使用可变分辨率功能电子显微镜表征了延性Pd $_{40}$ Ni $_{40}$ P $_{20}$和脆性Zr $_{52.5}$ Cu $_{17.9}$ Ni $_{14.6}$ Al $_{10}$ Ti $_5$(Vit 105)的中程有序(MRO)。在这里,我们表明存在的第二个较大的MRO相关长度的韧性材料,这是不存在于脆性材料。与文献的比较表明,较大的相关长度占较大的剪切转换区(STZ),增加了非均质性。这使得更容易形成剪切带,从而解释了变形能力的差异。