Modeling and simulation on ultrafine-graining based on multiscale crystal plasticity considering dislocation patterning

Aoyagi, Yoshiteru; Kobayashi, Ryotaro; Kaji, Yoshiyuki; Shizawa, Kazuyuki

doi:10.1016/j.ijplas.2012.12.007

Cited by 35 publications

(8 citation statements)

References 38 publications

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“…Ultrafine grained (UFG, 100 nm < grain size d < 1 m) or nanocrystalline (NC, d < 100 nm) metals fabricated by severe plastic deformation (SPD) processes have been extensively investigated due to their high strength compared to coarse-grained (CG) metals; see e.g., [1][2][3][4][5][6][7][8][9][10][11]. Much attention has been paid to the UFG/NC face-centered cubic (FCC) materials, which demonstrate unique mechanical behaviors such as high strength, reduced or even no strain hardening, high strain rate sensitivity, etc.…”

Section: Introductionmentioning

confidence: 99%

Hardening by Annealing and Implementation of High Ductility of Ultra-Fine Grained Aluminum: Experiment and Theory

Orlova

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Mavlyutov

et al. 2018

Reviews on Advanced Materials Science

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The influence of low temperature annealing and subsequent deformation on microstructure, strength and ductility was investigated for the first time for high pressure torsion (HPT) processed commercially pure Al. Extremely high increases in the conventional yield stress (up to 50%) and ultimate tensile strength (up to 30%) were obtained by annealing of the ultrafine grained (UFG) samples in the range 90-200 °C for 1 h. Such increases were accompanied by a sharp drop in ductility up to 1%. Implementation of high ductility at the level of coarse-grained Al, while maintaining high strength of the HPT-processed sample was demonstrated for the first time and achieved by repeating the low temperature annealing followed by subsequent additional HPT deformation. The key role of relaxation of non-equilibrium high-angle grain boundaries (GBs) in the strengthening effect of UFG-Al by annealing is shown. Two theoretical models are suggested to explain the hardening by annealing and the implementation of high ductility in UFG structures. Within the models, plastic deformation occurs through emission of lattice dislocations from triple junctions of GBs containing pile-ups of grain-boundary dislocations, glide of the lattice dislocations across neighboring grains, their accumulation at and climb along the opposite GBs. The energy characteristics and the critical stresses of dislocation emission are determined in two different cases, for UFG Al subjected to annealing only and to annealing with subsequent additional HPT deformation. The calculated theoretical dependences of the flow stress on the plastic deformation value well fit qualitatively and quantitatively to our experimental data.

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Section: Introductionmentioning

confidence: 99%

Hardening by Annealing and Implementation of High Ductility of Ultra-Fine Grained Aluminum: Experiment and Theory

Orlova

Скиба

Mavlyutov

et al. 2018

Reviews on Advanced Materials Science

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“…12for strain invariant and in the expression of acoustic resistance of the medium, which enters into Eq. (13). It is also shown above that the coefficient from Eq.…”

Section: Plastic and Acoustic Characteristics Of The Deforming Mediummentioning

confidence: 69%

“…Naturally, we can do no more than mention a few experimental and theoretical studies related to dislocation physics and solids mechanics, e.g. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. We have recently made a significant discovery that the deforming medium is a self-organizing system, which is in a state far from thermodynamic equilibrium; such media are addressed by [15][16][17][18][19][20][21][22][23][24].…”

Section: Introduction General Considerationmentioning

confidence: 99%

Autowave Mechanics of Plastic Flow

Зуев

2020

Springer Tracts in Mechanical Engineering

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The notions of plastic flow localization are reviewed here. It have been shown that each type of localized plasticity pattern corresponds to a given stage of deformation hardening. In the course of plastic flow development a changeover in the types of localization patterns occurs. The types of localization patterns are limited to a total of four pattern types. A correspondence has been set up between the emergent localization pattern and the respective flow stage. It is found that the localization patterns are manifestations of the autowave nature of plastic flow localization process, with each pattern type corresponding to a definite type of autowave. Propagation velocity, dispersion and grain size dependence of wavelength have been determined experimentally for the phase autowave. An elastic-plastic strain invariant has also been introduced to relate the elastic and plastic properties of the deforming medium. It is found that the autowave’s characteristics follow directly from the latter invariant. A hypothetic quasi-particle has been introduced which correlates with the localized plasticity autowave; the probable properties of the quasi-particle have been estimated. Taking the quasi-particle approach, the characteristics of the plastic flow localization process are considered herein.

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“…For many metallic devices, the length scale ranges typically from below hundred nanometers up to tens of micrometers. For plasticity in micrometer-size specimens, modelling such deformation becomes amendable to continuum approaches [1][2][3][4][5][6] that consider the dislocation microstructure in an averaged sense by densities. For polycrystals the crystal plasticity finite element method was used to study strain rate effects on aluminum single crystals [7].…”

Section: Introductionmentioning

confidence: 99%

Predicting the flow stress and dominant yielding mechanisms: analytical models based on discrete dislocation plasticity

Song

Liu

et al. 2019

Sci Rep

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Dislocations are the carriers of plasticity in crystalline materials. Their collective interaction behavior is dependent on the strain rate and sample size. In small specimens, details of the nucleation process are of particular importance. In the present work, discrete dislocation dynamics (DDD) simulations are performed to investigate the dominant yielding mechanisms in single crystalline copper pillars with diameters ranging from 100 to 800 nm. Based on our simulations with different strain rates and sample size, we observe a transition of the relevant nucleation mechanism from “dislocation multiplication” to “surface nucleation”. Two physics-based analytical models are established to quantitatively predict this transition, showing a good agreement for different strain rates with our DDD simulation data and with available experimental data. Therefore, the proposed analytical models help to understand the interplay between different physical parameters and nucleation mechanisms and are well suitable to estimate the material strength for different material properties and under given loading conditions.

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Modeling and simulation on ultrafine-graining based on multiscale crystal plasticity considering dislocation patterning

Cited by 35 publications

References 38 publications

Hardening by Annealing and Implementation of High Ductility of Ultra-Fine Grained Aluminum: Experiment and Theory

Hardening by Annealing and Implementation of High Ductility of Ultra-Fine Grained Aluminum: Experiment and Theory

Autowave Mechanics of Plastic Flow

Predicting the flow stress and dominant yielding mechanisms: analytical models based on discrete dislocation plasticity

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