On the effect of grain size on yield stress: extension into nanocrystalline domain

Benson, David J.; Fu, Hsueh-Hung; Meyers, Marc A.

doi:10.1016/s0921-5093(00)02029-3

Cited by 80 publications

(43 citation statements)

References 23 publications

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“…The nanocrystalline materials have been considered as a three-component composite consisting of grains, grain boundaries and triple junctions, where three-grain boundaries meet [30], or a four-component composite consisting of crystallite (grain interior), grain boundaries, triple lines and quadruple nodes [31]. For the sake of simplicity, the nanocrystalline materials could be approximated as a composite with two phases onlygrain interior and grain boundary [32][33][34][35], since all plastic deformation was observed to be accommodated in the grain boundary and no intra-grain deformation occurred [22,23]. The grain phase then represents the grain cores while the matrix phase represents a blend of grain boundaries, triple junctions and/or quadruple nodes.…”

Section: Introductionmentioning

confidence: 99%

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Bhole

Chen

2008

Science and Technology of Advanced Materials

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A model was developed to describe the grain size dependence of hardness (or strength) in nanocrystalline materials by combining the Hall-Petch relationship for larger grains with a coherent polycrystal model for nanoscale grains and introducing a log-normal distribution of grain sizes. The transition from the Hall-Petch relationship to the coherent polycrystal mechanism was shown to be a gradual process. The hardness in the nanoscale regime was observed to increase with decreasing grain boundary affected zone (or effective grain boundary thickness, ) in the form of −1/2 . The critical grain size increased linearly with increasing . The variation of the calculated hardness value with the grain size was observed to be in agreement with the experimental data reported in the literature.

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Section: Introductionmentioning

confidence: 99%

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Bhole

Chen

2008

Science and Technology of Advanced Materials

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“…Fu et al [33,34] and Benson et al [35] proposed a mantle-core model of nanocrystalline materials, in which a monocrystalline core is surrounded by a grainboundary region mantle with a high work hardening rate. They calculated plastic flow as a function of grain size taking into account the dislocation accumulation rates in grainboundary regions and grain interiors.…”

Section: Multi-element Composite Models and Homogenizationmentioning

confidence: 99%

“…A series of homogenization based models of nanocrystalline materials taking into account various deformation mechanisms has been developed by Capolungo, Cherkaoui and their colleagues [33][34][35][36][37][38][39][40]. In [33], the authors employed the homogenization method to evaluate the grain size effect on the deformation of nanocrystalline materials, assuming elastic-perfect plastic behaviour of grain boundaryphase and elastic-viscoplastic behaviour of grain core phase.…”

Section: Multi-element Composite Models and Homogenizationmentioning

confidence: 99%

“…Also, the homogenization methods have been improved, from easiest rule-of-mixture [22], to more complex composite models, like Christensen and Lo self-consistent scheme [43], Mori-Tanaka and hierarchical models [33][34][35][36][37][38][39][40] or real structure models with experimentally determined lognormal grain size distribution [28,29].…”

Section: Multi-element Composite Models and Homogenizationmentioning

confidence: 99%

“…Among the constitutive laws used in some models, one can list the grain size dependent plasticity (for grain interior/GI) and amorphous glass model (GB) [21], anisotropic elasto-plastic models with different orientations (GI) and Voce-hardening law with high work hardening rate. Depending on the distance from the closest grain boundary (GB) [33,35], isotropic, linear hardening behaviour (GI) and isotropic power-law type rate dependent constitutive response (GB) [27], dislocation glide model (GI) and diffusional (Coble creep and Nabarro-Herring creep) deformation [22][23][24][25], unified viscoplastic constitutive law [6], elastic-viscoplastic behaviour and dislocation glide (GI) and elastic perfect plastic behaviour incorporating the model of grain boundary dislocation emission and penetration (GB) [33][34][35][36][37][38][39][40], crystal viscoplasticity with Hall Petch grain size dependence (GI) and isotropic viscoplasticity and Mohr-Coulomb pressure dependence (GB) [47] .…”

Section: Dislocation Mechanisms Of Deformation and Polycrystal Plastimentioning

confidence: 99%

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Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Mishnaevsky

Левашов

2015

Computational Materials Science

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Abstract:An overview of micromechanical models of strength and deformation behaviour of nanostructured and ultrafine grained metallic materials is presented. Composite models of nanomaterials, polycrystal plasticity based models, grain boundary sliding, the effect of nonequilibrium grain boundaries and nanoscale properties are discussed and compared. The examples of incorporation of peculiar nanocrystalline effects (like large content of amorphous or semi-amorphous grain boundary phase, partial dislocation GB emission/glide/GB absorption based deformation mechanism, diffusion deformation, etc.) into continuum mechanical approach are given. The possibilities of using micromechanical models to explore the ways of the improving the properties of nanocrystalline materials by modifying their structures (e.g., dispersion strengthening, creating non-equilibrium grain boundaries, varying the grain size distributions and gradients) are discussed.Keywords: Micromechanics; Finite element modelling; Nanomaterials; Nanocrystalline materials IntroductionDuring recent decades, growing interest of scientific community has been attracted to the nanostructured materials. The expectations on nanostructuring as a way to enhance material performances and to improve competing materials properties are very high, and some of them have been delivered, indeed.The extraordinary properties of nanocrystalline and ultrafine grained metallic materials (i.e., materials with the grain sizes of the order of several to several hundred nanometers) include superductility at room temperature, high hardness and high strength 2 to hardness value (which might be 2…7 times higher than in coarse grained materials), lower elastic modulus, negative Hall-Petch slope, enhanced strain rate sensitivity and difference between tensile and compression response [1][2][3][4][5]. The yield strength of nanocrystalline materials can be up to 5…10 times higher than of coarse-grained materials [6]. Other peculiar effect of nanocrystalline materials are the deviation fromHall-Petch relation at ultrafine and nanoscale grain sizes (below 100 nm), which goes into negative Hall Petch slope at about 10 nm, as well as asymmetry of tensile and compressive behaviour and enhanced diffusion properties [7].In order to predict the service properties of the materials and to explore the potential and reserves of their improvement, computational models linking the macroscale (service) In this paper, we present an overview of micromechanical models of nanocrystalline and ultrafine grained materials, their mechanical behaviour, deformation and strength.Composite models, crystal plasticity based models, grain boundary sliding, the effect of non-equilibrium grain boundaries, etc. are reviewed. The main constraints and challenges in the considered models are discussed. Composite models of nanocrystalline metallic materialsThe main structural feature of nanocrystalline and ultrafine grained materials, apart from the small grain sizes, is the high relative volume of grain boundary surface pha...

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Grain Size Dependence of the Work Hardening Process in Al99.99

Kovács

Chinh

Kovács-Csetényi

2002

phys. stat. sol. (a)

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The work hardening properties of 99.99% purity aluminum were investigated by tensile tests at RT on samples with average grain sizes between 40 and 300 μm. It is shown that the stress–strain curves can only be described by two different functions valid at moderate and at higher strains, respectively. New constitutive equations due to these two different stages are derived on the basis of a new phenomenological model, and their validity is proved by experimental results. It is shown that the work hardening parameters depend strongly on the grain size in the first stage, while the rate of hardening in the second stage is independent of the grain size. The constitutive equations derived are used to analyze the grain size dependence of the flow stress as a function of the strain.

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On the effect of grain size on yield stress: extension into nanocrystalline domain

Cited by 80 publications

References 23 publications

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Grain Size Dependence of the Work Hardening Process in Al99.99

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