Transition of deformation mechanisms and its connection to grain size distribution in nanocrystalline metals

Zhu, B.; Asaro, R.J.; Krysl, Petr; Bailey, R.

doi:10.1016/j.actamat.2005.06.033

Cited by 129 publications

(82 citation statements)

References 20 publications

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“…The first experiment is on the NC Cu under uniaxial tension was reported in Sanders et al (1997), and the second experiment on NC Ni uniaxial tension was reported in Zhu et al (2005). Figure 11.…”

Section: Resultsmentioning

confidence: 99%

Overall mechanical behavior of nanocrystalline materials accompanied by damage evolution on grain boundaries

Chen

Wei

2013

International Journal of Damage Mechanics

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In the present research, overall mechanical behaviors of the nanocrystalline materials considering the grain boundary damage evolutions are investigated systematically. A mixed-mode cohesive interface model is used to describe the mixed deformation and fracture process of grain boundaries. Based on the mixed-mode cohesive interface model, the grain boundary damage and damage evolution are defined and characterized. In order to describe the size effect, the strain gradient plasticity theory is used for grain materials. In the present results, the overall stress-strain relations and the corresponding damage evolution curves are obtained as functions of several independent parameters, such as the mixed separation strength, the mixed critical energy release rate, grain size, Young's modulus as well as strain hardening exponent. The present results show that both the overall strength and ductility of the nanocrystalline materials are closely dependent on the grain boundary strength and the damage evolution behaviors. By means of the damage evolution relations, the features of the overall stress-strain curves can be clearly interpreted.

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Section: Resultsmentioning

confidence: 99%

Overall mechanical behavior of nanocrystalline materials accompanied by damage evolution on grain boundaries

Chen

Wei

2013

International Journal of Damage Mechanics

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“…The critical resolved shear stress for triggering the nucleation of partial dislocations is described by previous works. 103,201,202 The maximum strength occurs when both twinning and the inclined dislocation slip are active. In addition, it is found that the maximum strength gradually increases when the critical twin spacing for the strengthening to softening transition decreases along with the decrease of grain size.…”

Section: -151mentioning

confidence: 99%

Nanotwinned and hierarchical nanotwinned metals: a review of experimental, computational and theoretical efforts

Sun

2018

npj Comput Mater

122

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The recent studies on nanotwinned (NT) and hierarchical nanotwinned (HNT) face-centered cubic (FCC) metals are presented in this review. The HNT structures have been supposed as a kind of novel structure to bring about higher strength/ductility than NT counterparts in crystalline materials. We primarily focus on the recent developments of the experimental, atomistic and theoretical studies on the NT and HNT structures in the metallic materials. Some advanced bottom-up and top-down techniques for the fabrication of NT and HNT structures are introduced. The deformation induced HNT structures are available by virtue of severe plastic deformation (SPD) based techniques while the synthesis of growth HNT structures is so far almost unavailable. In addition, some representative molecular dynamics (MD) studies on the NT and HNT FCC metals unveil that the nanoscale effects such as twin spacing, grain size and plastic anisotropy greatly alter the performance of NT and HNT metals. The HNT structures may initiate unique phenomena in comparison with the NT ones. Furthermore, based on the phenomena and mechanisms revealed by experimental and MD simulation observations, a series of theoretical models have been proposed. They are effective to describe the mechanical behaviors of NT and HNT metals within the applicable scope. So far the development of manufacturing technologies of HNT structures, as well as the studies on the effects of HNT structures on the properties of metals are still in its infancy. Further exploration is required to promote the design of advanced materials.

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“…Wei and Gao [63] extended this model by Zhu et al [60] by including the deformation by grain boundary diffusion. Using the developed elastic-viscoplastic model, which incorporates all the main deformation mechanisms, grain-boundary sliding, grainboundary diffusion, grain-interior diffusion and grain-interior plasticity, they studied the deformation of nCu and showed that the relative contribution of different mechanisms depends on both grain size and the applied strain rate.…”

Section: Dislocation Mechanisms Of Deformation and Polycrystal Plastimentioning

confidence: 99%

“…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%

“…They determined fractions of plastic strain due to different mechanisms. Also, Zhu et al [60] modelled grain boundary sliding using the phenomenological kinetic relations by Conrad and Narayan and analyzed the transition between dislocations based deformation and GBS. They concluded that GBS starts to contribute to the deformation at the grain size below 15…”

Section: Grain Boundary Slidingmentioning

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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Transition of deformation mechanisms and its connection to grain size distribution in nanocrystalline metals

Cited by 129 publications

References 20 publications

Overall mechanical behavior of nanocrystalline materials accompanied by damage evolution on grain boundaries

Overall mechanical behavior of nanocrystalline materials accompanied by damage evolution on grain boundaries

Nanotwinned and hierarchical nanotwinned metals: a review of experimental, computational and theoretical efforts

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

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