Length scale effects on the shear localization process in metallic glasses: A theoretical and computational study

Thamburaja, T Prakash G.

doi:10.1016/j.jmps.2011.04.018

Cited by 70 publications

(37 citation statements)

References 48 publications

(113 reference statements)

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“…For example, intuitively derived law between shear strain and local dilatation has been used in constitutive modelings of MGs [29]. Shear is not necessarily the only deformation mode accommodating the local atomic rearrangement.…”

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Direct atomic-scale evidence for shear–dilatation correlation in metallic glasses

et al. 2016

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Direct atomic-scale evidence is presented for the shear-dilatation correlation in metallic glasses via molecular dynamics and first-principles calculations. A quantitative parabolic relationship is established between the atomic local shear and hydrostatic volumetric strains by carrying out statistical analysis on a deformed glass model. The correction is further verified by density functional theory. Our atomistic demonstration of shear-dilatation correlation collaborates with the experimentally observed a few percent volume change in shear bands. It brings quantitative insights into the unique correlation between shear transformation and cavitation in metallic glasses.© 2015 Elsevier Ltd. All rights reserved.Metallic glasses (MGs) are a category of promising high strength structural materials with many other superior physical and chemical properties [1]. The deformation mechanisms of such amorphous solid state are in sharp contrast with their crystalline counterparts since there are no long-range atoms packing pattern in MGs [2,3]. No conventional mechanisms, such as ordinary dislocation plasticity or deformation twinning in crystals, exist in MGs which can carry plastic deformation. Therefore MGs usually suffer from the notorious catastrophic failure with a strong strain localization (shear banding) phenomenon [4,5].Several models have been proposed to rationalize the inelastic deformation of MGs, which include free volume [6], shear transformation zone (STZ) [7][8][9], cooperative shear model (CSM) [10,11], flow unit [12], vibrational soft spot [13], shear-diffusive transformation [14,15], and our recently proposed tensile transformation zone (TTZ) [16][17][18]. All of these models are based on the local structural rearrangement of atoms via the interplay of atomic-scale shear and dilation/contraction in MGs [19][20][21][22][23][24]. Among them, Argon's STZ model involves local rearrangement of a cluster of atoms undergoing a stress-driven, and thermally activated shear distortion [25,23,24]. Whereas Spaepen's free volume model is based on a dynamic equilibrium between the stress-assisted creation and annihilation of free volume [6]. The free volume behaviors can be regarded as dilation and contraction of local atomic environments. Since both models have been successfully adopted to describe the homogeneous and inhomogeneous flows in MGs, there should be some intrinsic correlation between shear and dilatation/compaction during deformation of glasses [21,26].Generally, shear-dilatation correlation is an intrinsic nature of deformation in amorphous alloys although local compaction is also allowed [27,28]. For example, intuitively derived law between shear strain and local dilatation has been used in constitutive modelings of MGs [29]. Shear is not necessarily the only deformation mode accommodating the local atomic rearrangement. The microscopic scenario is that the STZ operations redistribute stress spatially which usually leads to the creation of free volume via atomic-scale dilatation [21,1]. So that local ...

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Direct atomic-scale evidence for shear–dilatation correlation in metallic glasses

et al. 2016

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“…In the same line, Lapovok et al [80] proposed a physical definition of the length scale on the basis of the current dislocation cell size which is modified according to the deformation history. In the context of gradient models for metallic glasses, the length scale parameter is related to the fracture process zone size [81][82][83]. For an extensive overview of the identification and quantification of the length scale in gradient models the interested reader is referred to [84] where it is stated that a current trend is to relate the length scale parameters to the heterogeneity of the material.…”

Section: Choice Of Length Scale Based On the Grain Sizementioning

confidence: 99%

Fourth-order strain-gradient phase mixture model for nanocrystalline fcc materials

Klusemann

Bargmann

Estrin

2016

Modelling Simul. Mater. Sci. Eng.

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The proposed modeling approach for nanocrystalline materials is an extension of the local phase mixture model introduced by Kim et al (2000 Acta Mater. 48 493–504). Local models cannot account for any non-uniformities or strain patterns, i.e. such models describe the behavior correctly only as long as it is homogeneous. In order to capture heterogeneities, the phase mixture model is augmented with gradient terms of higher order, namely second and fourth order. Different deformation mechanisms are assumed to operate in grain interior and grain boundaries concurrently. The deformation mechanism in grain boundaries is associated with diffusional mass transport along the boundaries, while in the grain interior dislocation glide as well as diffusion controlled mechanisms are considered. In particular, the mechanical response of nanostructured polycrystals is investigated. The model is capable of correctly predicting the transition of flow stress from Hall–Petch behavior in conventional grain size range to an inverse Hall–Petch relation in the nanocrystalline grain size range. The consideration of second- and fourth-order strain gradients allows non-uniformities within the strain field to represent strain patterns in combination with a regularization effect. Details of the numerical implementation are provided.

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“…21,22 Therefore, we obtain the following pressure-sensitive von Mises (or Drucker-Prager) plastic yield criterion by taking the rate-dependent plastic shear strain kinetic equation of Thamburaja 23 and Bargmann et al 24 in the rate-independent limit…”

Section: Figurementioning

confidence: 99%

The plastic yield and flow behavior in metallic glasses

Thamburaja

Klusemann

Adibi

et al. 2015

Applied Physics Letters

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Metallic glasses have vast potential applications as components in microelectronics- and nanoelectronics-type devices. The design of such components through computer simulations requires the input of a faithful set of continuum-based constitutive equations. However, one long-standing controversial issue in modeling the plastic behavior of metallic glasses at the continuum level is the use of the most appropriate plastic yield criterion and flow rule. Guided by a series of molecular dynamics simulations conducted at low-homologous temperatures under homogeneous deformations, we quantitatively prove that the continuum plastic behavior in metallic glasses is most accurately described by a von Mises-type plastic yield criterion and flow rule.

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Length scale effects on the shear localization process in metallic glasses: A theoretical and computational study

Cited by 70 publications

References 48 publications

Direct atomic-scale evidence for shear–dilatation correlation in metallic glasses

Direct atomic-scale evidence for shear–dilatation correlation in metallic glasses

Fourth-order strain-gradient phase mixture model for nanocrystalline fcc materials

The plastic yield and flow behavior in metallic glasses

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