Plastic flow in polycrystal states in a binary mixture

Hamanaka, Toshihiko; Shiba, Hayato; Ōnuki, Akira

doi:10.1103/physreve.77.042501

Cited by 12 publications

(25 citation statements)

References 29 publications

(46 reference statements)

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“…In this paper, we will present MD simulations extending those in our previous papers [14,58]. We will examine the crossover among crystal, polycrystal, and glass with varying the composition c in a model 2D binary mixture with shear.…”

Section: Introductionmentioning

confidence: 98%

Plastic deformations in crystal, polycrystal, and glass in binary mixtures under shear: Collective yielding

Shiba

Ōnuki

2010

Phys. Rev. E

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Using molecular dynamics simulation, we examine the dynamics of crystal, polycrystal, and glass in a Lennard-Jones binary mixture composed of small and large particles in two dimensions. The crossovers occur among these states as the composition c is varied at fixed size ratio. Shear is applied to a system of 9000 particles in contact with moving boundary layers composed of 1800 particles. The particle configurations are visualized with a sixfold orientation angle αj(t) and a disorder variable Dj(t) defined for particle j, where the latter represents the deviation from hexagonal order. Fundamental plastic elements are classified into dislocation gliding and grain boundary sliding. At any c, large-scale yielding events occur on the acoustic time scale. Moreover, they multiply occur in narrow fragile areas, forming shear bands. The dynamics of plastic flow is highly hierarchical with a wide range of time scales for slow shearing. We also clarify the relationship between the shear stress averaged in the bulk region and the wall stress applied at the boundaries.

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Section: Introductionmentioning

confidence: 98%

Plastic deformations in crystal, polycrystal, and glass in binary mixtures under shear: Collective yielding

Shiba

Ōnuki

2010

Phys. Rev. E

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“…To this end, we divided the system into three regions. 31), 56) In the bulk region −0.5L < x, y < 0.5L, we initially placed particles with N = 9000. We added two boundary layers in the region −0.6L < y < −0.5L at the bottom and in the region 0.5L < y < 0.6L at the top.…”

Section: Averaged Velocitymentioning

confidence: 99%

“…45)-47) Plastic deformations in crystal and polycrystal are extremely complex and are still poorly understood despite their extensive research. 48)- 56) In crystal with lowdensity defects, dislocation motions play a major role in plasticity, where they yield slip planes with various sizes as observed in acoustic emission experiments 49) and…”

Section: §1 Introductionmentioning

confidence: 99%

“…50) In polycrystal, the particles in the vicinity of grain boundaries are relatively mobile compared to those within the grains, so their collective motions give rise to sliding of the grain boundaries under applied stress. 54)- 56) In these systems, plastic events take place as bursts or avalanches spanning wide ranges of space and time scales. In this manner, they intermittently release the elastic energy stored in the crystalline regions at high strain.…”

Section: §1 Introductionmentioning

confidence: 99%

“…6), 14), 56) We are interested in the relationship between the dynamic heterogeneity on long time scales and the structural heterogeneity in the particle configurations. In a separate paper we have examined rheology and plastic deformations on various time scales.…”

Section: §1 Introductionmentioning

confidence: 99%

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Jammed Particle Configurations and Dynamics in High-Density Lennard-Jones Binary Mixtures in Two Dimensions

Shiba¹,

Ōnuki²

2010

Prog. Theor. Phys. Suppl.

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We examine the changeover in the particle configurations and the dynamics in dense Lennard-Jones binary mixtures composed of small and large particles. By varying the composition at a low temperature, we realize crystal with defects, polycrystal with small grains, and glass with various degrees of disorder. In particular, we show configurations where small crystalline regions composed of the majority species are enclosed by percolated amorphous layers composed of the two species. We visualize the dynamics of configuration changes using the method of bond breakage and following the particle displacements. In quiescent jammed states, the dynamics is severely slowed down and is highly heterogeneous at any compositions. We apply shear flow by relative motions of boundary layers. Then plastic deformations multiply occur in relatively fragile regions, growing into large-scale shear bands where the strain is highly localized. Such bands appear on short time scales and evolve on long time scales with finite lifetimes.

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2D Stokesian Approach to Modeling Flow Induced Deformation of Particle Laden Interfaces

2017

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A Stokesian dynamics simulation of the effect of surface Couette flow on the microstructure of particles irreversibly adsorbed to an interface is presented. Rather than modeling both bulk phases, the interface, and particles in a full 3D simulation, known interfacial interactions between adsorbed particles are used to create a 2D model from a top down perspective. This novel methodology is easy to implement and computationally inexpensive, which makes it favorable to simulate behavior of particles under applied flow at fluid-fluid interfaces. The methodology is used to examine microstructure deformation of monodisperse, rigid spherical colloids with repulsive interactions when a surface Couette flow is imposed. Simulation results compare favorably to experimental results taken from literature, showing that interparticle forces must be 1 order of magnitude greater than viscous drag for microstructure to transition from aligned particle strings to rotation of local hexagonal domains. Additionally, it is demonstrated that hydrodynamic interactions between particles play a significant role in the magnitude of these microstructure deformations.

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Plastic flow in polycrystal states in a binary mixture

Cited by 12 publications

References 29 publications

Plastic deformations in crystal, polycrystal, and glass in binary mixtures under shear: Collective yielding

Plastic deformations in crystal, polycrystal, and glass in binary mixtures under shear: Collective yielding

Jammed Particle Configurations and Dynamics in High-Density Lennard-Jones Binary Mixtures in Two Dimensions

2D Stokesian Approach to Modeling Flow Induced Deformation of Particle Laden Interfaces

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