Plasticity of Ductile Metallic Glasses: A Self-Organized Critical State

Sun, Baoan; Yu, Hai Bin; Jiao, Wei; Bai, H. Y.; Zhao, Dongdong; Wang, W. H.

doi:10.1103/physrevlett.105.035501

Cited by 260 publications

(135 citation statements)

References 27 publications

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“…Avalanche behavior is observed across decades of length scale in small volumes of crystalline materials, metallic glasses, granular media, and earthquakes, to name a few systems of interest. [1][2][3][4][5][6][7][8][9][10][11][12] Metallic glasses, by virtue of their amorphous structure, have spatial variations in the amount of free volume. Regions of excess free volume nucleate shear transformation zones when the metallic glass is subjected to stress, and the collective propagation of shear transformation zones leads to shear banding/avalanche behavior.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Wright

Liu

et al. 2016

Journal of Applied Physics

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Two distinct types of slip events occur during serrated plastic flow of bulk metallic glasses. These events are distinguished not only by their size but also by distinct stress drop rate profiles. Small stress drop serrations have fluctuating stress drop rates (with maximum stress drop rates ranging from 0.3–1 GPa/s), indicating progressive or intermittent propagation of a shear band. The large stress drop serrations are characterized by sharply peaked stress drop rate profiles (with maximum stress drop rates of 1–100 GPa/s). The propagation of a large slip is preceded by a slowly rising stress drop rate that is presumably due to the percolation of slipping weak spots prior to the initiation of shear over the entire shear plane. The onset of the rapid shear event is accompanied by a burst of acoustic emission. These large slips correspond to simultaneous shear with uniform sliding as confirmed by direct high-speed imaging and image correlation. Both small and large slip events occur throughout plastic deformation. The significant differences between these two types require that they be carefully distinguished in both modeling and experimental efforts.

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Section: Introductionmentioning

confidence: 99%

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Wright

Liu

et al. 2016

Journal of Applied Physics

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“…They have been shown to occur either with a Gaussian size distribution, showing chaotic behaviour, or to obey a power-law-type size distribution, indicating self-organized criticality 12,13 . The arrest and reactivation of so-called shear bands, planar regions of highly-localized shear deformation with a thickness of about 10-200 nm (ref.…”

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confidence: 99%

Crossover from random three-dimensional avalanches to correlated nano shear bands in metallic glasses

et al. 2014

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When applying mechanical stress to a bulk metallic glass it responds with elastic and/or plastic deformations. A comprehensive microscopic theory for the plasticity of amorphous solids remains an open task. Shear transformation zones consisting of dozens of atoms have been identified as smallest units of deformation. The connexion between local formation of shear transformations zones and the creation of macroscopic shear bands can be made using statistical analysis of stress/energy drops or strain slips during mechanical loading. Numerical work has proposed a power law dependence of those energy drops. Here we present an approach to circumvent the experimental resolution problem using a waiting time analysis. We report on the power law-distributed deformation behaviour and the observation of a crossover in the waiting times statistics. This crossover indicates a transition in the plastic deformation behaviour from three-dimensional random activity to a two-dimensional nano shear band sliding.

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“…MGs have heterogeneous structure at the nanoscale [41,42], consisting of solidlike atomic clusters and liquidlike regions [42][43][44]. As strain increases, the distribution of atomic rearrangements reflect the dynamical response of the heterogeneous structures to the external stress [15,25,41].…”

Section: Discussionmentioning

confidence: 99%

Evolution of atomic rearrangements in deformation in metallic glasses

Shang

Yao

et al. 2014

Phys. Rev. E

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Atomic rearrangements induced by shear stress are fundamental for understanding deformation mechanisms in metallic glasses (MGs). Using molecular dynamic simulation, the atomic rearrangements characterized by nonaffine displacements (NADs) and their spatial distribution and evolution with tensile stress in Cu 50 Zr 50 MG were investigated. It was found that in the elastic regime the atomic rearrangements with the largest NADs are relatively homogeneous in space, but exhibit strong spatial correlation, become localized and inhomogeneous, and form large clusters as strain increases, which may facilitate the so-called shear transformation zones. Furthermore, initially they prefer to take place around Cu atoms which have more nonicosahedral configurations. As strain increases, the preference decays and disappears in the plastic regime. The atomic rearrangements with the smallest NADs are preferentially located around Cu atoms, too, but with more icosahedral or icosahedral-like atomic configurations. The preference is maintained in the whole deformation process. In contrast, the atomic rearrangements with moderate NADs distribute homogeneously, and do not show explicit preference or spatial correlation, acting as matrix during deformation. Among the atomic rearrangements with different NADs, those with largest and smallest NADs are nearest neighbors initially, but separating with increasing strain, while those with largest and moderate NADs always avoid to each other. The correlations in the fluctuations of the NADs confirm the long-range strain correlation and the scale-free characteristic of NADs in both elastic and plastic deformation, which suggests a universality of the scaling in the plastic flow in MGs.

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Plasticity of Ductile Metallic Glasses: A Self-Organized Critical State

Cited by 260 publications

References 27 publications

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Crossover from random three-dimensional avalanches to correlated nano shear bands in metallic glasses

Evolution of atomic rearrangements in deformation in metallic glasses

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