Micro-plasticity and intermittent dislocation activity in a simplified micro-structural model

Derlet, P. M.; Maaß, R.

doi:10.1088/0965-0393/21/3/035007

Cited by 31 publications

(39 citation statements)

References 58 publications

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“…The model has been solved analytically in the mean-field theory (MFT) approximation, which assumes that the interactions have infinite range, i.e., they do not decay with distance [22,23]. MFT exactly predicts the scaling behavior of the slip statistics in three dimensions as described below, and agrees well with discrete dislocation-dynamics simulations [24][25][26] and experiments [27]. In the following, we compute the slip statistics for sufficiently slow driving in the quasistatic limit.…”

Section: Model Assumptions and Experimental Detailssupporting

confidence: 53%

Slip statistics of dislocation avalanches under different loading modes

et al. 2015

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Slowly compressed microcrystals deform via intermittent slip events, observed as displacement jumps or stress drops. Experiments often use one of two loading modes: an increasing applied stress (stress driven, soft), or a constant strain rate (strain driven, hard). In this work we experimentally test the influence of the deformation loading conditions on the scaling behavior of slip events. It is found that these common deformation modes strongly affect time series properties, but not the scaling behavior of the slip statistics when analyzed with a mean-field model. With increasing plastic strain, the slip events are found to be smaller and more frequent when strain driven, and the slip-size distributions obtained for both drives collapse onto the same scaling function with the same exponents. The experimental results agree with the predictions of the used mean-field model, linking the slip behavior under different loading modes.

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Section: Model Assumptions and Experimental Detailssupporting

confidence: 53%

Slip statistics of dislocation avalanches under different loading modes

et al. 2015

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“…Currently there are two main variants of the universality class associated with the plastic deformation of crystalline materials, those for which the system is in a state of criticality irrespective of the applied external stress [46,58,59] and those for which the system is only in a state of criticality at (or close to) a critical depinning stress [60,61].…”

Section: Statistical Analysis Of Stress Dropsmentioning

confidence: 99%

In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated 〈1 1 1〉 Ni microspecimens

et al. 2015

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We report on the use of quantitative in situ microcompression experiments in a scanning electron microscope to systematically investigate the effect of self-ion irradiation damage on the full plastic response of h1 11i Ni. In addition to the well-known irradiation-induced increases in the yield and flow strengths with increasing dose, we measure substantial changes in plastic flow intermittency behavior, manifested as stress drops accompanying energy releases as the driven material transits critical states. At low irradiation doses, the magnitude of stress drops reduces relative to the unirradiated material and plastic slip proceeds on multiple slip systems, leading to quasi-homogeneous plastic flow. In contrast, highly irradiated specimens exhibit pronounced shear localization on parallel slip planes, which we ascribe to the onset of defect free channels normally seen in bulk irradiated materials. Our in situ testing system and approach allows for a quantitative study of the energy release and dynamics associated with defect free channel formation and subsequent localization. This study provides fundamental insight into the nature of interactions between mobile dislocations and irradiation-mediated and damage-dependent defect structures.

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“…On the other hand, other researchers (Dahmen et al, 2009;Derlet and Maaß, 2013;Friedman et al, 2012;Ng and Ngan, 2008c) pointed out that s 0 is not only related to sample size but also related to the current stress τ ( )…”

Section: The Cut-off Strain Smentioning

confidence: 99%

“…Self-organized criticality (SOC) model (Csikor et al, 2007;Zapperi et al, 1995) assumed that the cutoff size s max of the largest observed avalanche exclusively depends on the system size and not on the other experimental parameters. Meanwhile, mean-field theory (MFT) (Dahmen et al, 2009;Derlet and Maaß, 2013;Friedman et al, 2012;Ng and Ngan, 2008c) predicted that the cut-off size s max can also depend on stress. With two statistics gathered from experiments as input, Ng and Ngan (Ng and Ngan, 2008a) developed a Monte Carlo model to account for the jerky deformation during loading.…”

Section: Molecular Dynamics (Md) and Discrete Dislocation Dynamics (Dmentioning

confidence: 99%

A stochastic crystal plasticity model with size-dependent and intermittent strain bursts characteristics at micron scale

Lin

Liu

Cui

et al. 2015

International Journal of Solids and Structures

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Please cite this article as: Lin, P., Liu, Z., Cui, Y., Zhuang, Z., A stochastic crystal plasticity model with sizedependent and intermittent strain bursts characteristics at micron scale, International Journal of Solids and Structures (2015), doi: http://dx.Abstract: Size effect and strain bursts are widely observed in the plastic deformation of micron-sized single crystals. In this paper, a stochastic crystal plasticity model is established by importing these two dislocation-source-controlled characteristics into the conventional crystal plasticity theory. The plastic strain is composed of a series of strain bursts instead of formulated as a continuous function. The size of each strain burst follows a power-law distribution function and the rate of strain bursts is determined by a constitutive equation. On the other hand, size effect is accounted for by dislocation-source-controlled slip resistance. The effective dislocation source length is derived as a function of sample size by a statistical analysis and experimental data. Uniaxial compression of single crystal Ni micron-sized pillars, with diameters ranging from 5 to 40 µm, are investigated by the model. The results show that this model well captures the significant features of plastic deformation at micron scale: 1) Strain bursts are strongly affected by sample size. For large pillars (e.g. 40 µm), the stress-strain curves are almost continuous and predictable. But as sample size decreases, strain bursts become more and more evident and the stress-strain curves are unpredictable. 2)The yield strength increases significantly as sample size decreases. For diameter larger than 40 µm, the strengthening effect still exists but is not evident anymore. All these results match well with the experimental observations.

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Micro-plasticity and intermittent dislocation activity in a simplified micro-structural model

Cited by 31 publications

References 58 publications

Slip statistics of dislocation avalanches under different loading modes

Slip statistics of dislocation avalanches under different loading modes

In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated 〈1 1 1〉 Ni microspecimens

A stochastic crystal plasticity model with size-dependent and intermittent strain bursts characteristics at micron scale

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