Effects of grain size distribution on the mechanical response of nanocrystalline metals: Part II

Zhu, B.; Asaro, R.J.; Krysl, Petr; Zhang, K.; Weertman, J.

doi:10.1016/j.actamat.2006.03.022

Cited by 88 publications

(49 citation statements)

References 18 publications

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“…Zhang and Tong [17] presented the numerical computation of 3D as a general investigation tool that featured an aggregate computation including element type and geometrical representation of grain boundary. Based on voronoi tessellation, lognormal and gamma distribution were used to describe the distribution of grain size in polycrystalline by Zhu et al [18] and Dalla et al [19].…”

Section: Introductionmentioning

confidence: 99%

Modelling of size effects in microforming process with consideration of grained heterogeneity

Wei

Jiang

et al. 2013

Computational Materials Science

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Size effect is a special phenomenon in metal micro-forming process. As the deformation process is scale down to micro/mesoscale, the characteristics of single grain involved in the deformed region play a significant role on the material mechanical behaviours resulting in the invalidation of classical theories in microforming. This paper presents a newly developed material model in microscale on the basis of the grained heterogeneity (e.g. grain size, shape and deformability) and specimen dimension. Voronoi tessellation has been employed to describe the polycrystalline aggregate. The grain shape is controlled by the centroidal-voronoi algorithm to drive grains into steady state. Hardness of the grains obtained from Nano-indentation is used to identify the scatter of the grained deformability. Applying the new material model, the micro-compression test of pure copper is numerically simulated by finite element method (FEM). The influences of grain size and feature size on the deformation behaviours are discussed. The numerical simulation results are in good agreement with the experimental results in terms of the flow stress curves and profile of deformed parts. Based on the novel material model, a FE model of microcross wedge rolling is established and the obtained results show the strain of specimen core region increases with the magnification of grain size. © 2013 Elsevier B.V. All rights reserved. AbstractSize effect is a special phenomenon in metal micro-forming process. As the deformation process is scale down to micro/meso scale, the characteristics of single grain involved in the deformed region play a significant role on the material mechanical behaviours resulting in the invalidation of classical theories in microforming. This paper presents a newly developed material model in micro scale on the basis of the grained heterogeneity (e.g. grain size, shape and deformability) and specimen dimension. Voronoi tessellation has been employed to describe the polycrystalline aggregate. The grain shape is controlled by the centroidal-voronoi algorithm to drive grains into steady state. Hardness of the grains obtained from Nano-indentation is used to identify the scatter of the grained deformability. Applying the new material model, the micro-compression test of pure copper is numerically simulated by finite element method (FEM). The influences of grain size and feature size on the deformation behaviours are discussed. The numerical simulation results are in good agreement with the experimental results in terms of the flow stress curves and profile of deformed parts. Based on the novel material model, a FE model of micro cross wedge rolling is established and the obtained results show the strain of specimen core region increases with the magnification of grain size.

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Section: Introductionmentioning

confidence: 99%

Modelling of size effects in microforming process with consideration of grained heterogeneity

Wei

Jiang

et al. 2013

Computational Materials Science

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“…As mentioned in the introduction, both grain size and grain size distribution could play important roles in determining the responses of NC metals [47]. In this part, we will present a modified EVPSC method with considering grain size distribution to bridge the gap between the microscopic mechanical behaviour of individual grains and macroscopic mechanical behaviour of NC.…”

Section: Elasto-viscoplastic Self-consistent Methods With Grain Size Dmentioning

confidence: 99%

“…First, based on the classical self-consistent theory, a representative element volume (RVE) is chosen as shown in figure 1a, which contains N GIs with different grain sizes and between them are the GBs [53]. The grain size distribution follows the log-normal distribution as represented by Zhu et al [47], i.e.…”

Section: Elasto-viscoplastic Self-consistent Methods With Grain Size Dmentioning

confidence: 99%

“…However, in this EVPSC method, the volume fraction of each individual grain is assumed to be the same without considering the grain size distribution. While, it should be noted that as the size effect becomes important at nanoscale, the grain size distribution of NC materials may have a significant influence on the macroscopic mechanical behaviours [46,47]. Therefore, in this work, a modified EVPSC method considering grain size distribution for different volume fractions of individual grains will be proposed for the scale transition.…”

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confidence: 99%

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Mechanical properties for irradiated face-centred cubic nanocrystalline metals

et al. 2015

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“…Using this approach, Zhu, Asaro and colleagues [60,61] developed a polycrystalline constitutive model of nanocrystalline materials (electrodeposited Ni), and studied the effect of the grain size distribution (taken as lognormal probability distribution) on the mechanical behaviour of nanonickel. The model takes into account the simultaneous contributions of deformation mechanisms including grain boundary emission of dislocations and/or stacking faults, as well as for grain boundary sliding.…”

Section: Dislocation Mechanisms Of Deformation and Polycrystal Plastimentioning

confidence: 99%

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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Effects of grain size distribution on the mechanical response of nanocrystalline metals: Part II

Cited by 88 publications

References 18 publications

Modelling of size effects in microforming process with consideration of grained heterogeneity

Modelling of size effects in microforming process with consideration of grained heterogeneity

Mechanical properties for irradiated face-centred cubic nanocrystalline metals

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

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