The effect of grain size diversity on the flow stress of nanocrystalline metals by finite-element modelling

Dobosz, Romuald; Lewandowska, M.; Kurzydłowski, Krzysztof J.

doi:10.1016/j.scriptamat.2012.05.043

Cited by 19 publications

(15 citation statements)

References 26 publications

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“…There are several factors influencing the deviation from the Hall-Petch relationship. First, the Hall-Petch analysis only considers average grain size, while real grain structures exhibit various grain size distributions, which have been shown to affect the strength of metals [49]. Also, the populations of grain boundaries may differ significantly, which strongly affects the strength of metals [50,51].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

The influence of an ECAP-based deformation process on the microstructure and properties of electrolytic tough pitch copper

2017

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Samples of electrolytic tough pitch copper were deformed in equal channel angular pressing with enhanced productivity to quickly refine its initial coarsegrained microstructure at room temperature. The evolution in microstructure and changes in a broad range of properties were compared to a sample in the undeformed state. The microstructure evolution was evaluated using electron backscatter diffraction for both states and transmission electron microscopy for a detailed microstructure characterization of the deformed sample. The microstructure observations were correlated with the results of tensile tests, electrochemical tests in 3.5 wt% NaCl, electrical conductivity measurements and thermal stability up to 200°C. The ECAP process employed in this study caused a grain refinement from about 16 µm to about 600 nm. The microstructure refinement caused a 50% increase in both the YS and UTS. The elongation to failure, due to the high amount of LAGBs, maintained a high value of 13.3%. The corrosion and pitting potentials were higher for the deformed sample. Furthermore, the grain refinement caused a decrease in electrical conductivity from 100.2% IACS to 93.1% IACS, a drop of 7% IACS. The deformed sample displayed thermal stability up to a temperature of 175°C, where there was a drop in micro-hardness of more than 10%.

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Section: Mechanical Propertiesmentioning

confidence: 99%

The influence of an ECAP-based deformation process on the microstructure and properties of electrolytic tough pitch copper

2017

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“…Some groups of researchers used the quasireal (e.g., Voronoi tessellation based) representations of structures, with some real structure parameters, to represent realistic microstructures of nanometals [28][29][30][31] (see an example Figure 1c). So, Mercier et al [32] considered nanocrystalline material as an aggregate of spherical grains, with random grain sizes, distributed according to lognormal probability distribution.…”

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%

“…Using the approach developed in [29] (multigrain Voronoi based composite model), Dobosz et al [99] studied numerically the effect of second phase particles at grain boundaries. They concluded that the particles located at GBS may lead to the material strengthening, if the material is deformed by GBS mechanism; otherwise, their effect is negligible.…”

Section: Non-equilibrium Grain Boundaries and Gb Defects In Nanocrystmentioning

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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“…At an essential crystallite size, we could no longer utilize the approach of a pile-up mechanism in order to define the plastic flow. As the GI size decreased to the NC regime, the number of dislocations at the The material properties employed for the numerical investigation of the mechanical response of the nanocrystalline copper were established through the open literature review [21][22][23] of bilinear stress-strain curves, defined by values of yield stresses. The aforementioned material properties presumed in the simulations are presented in Table 1.…”

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confidence: 99%

Numerical Computation of Material Properties of Nanocrystalline Materials Utilizing Three-Dimensional Voronoi Models

Bazios

Τσερπές

Pantelakis

2019

Metals

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Nanocrystalline metals have been the cause of substantial intrigue over the past two decades due to their high strength, which is highly sensitive to their microstructure. The aim of the present project is to develop a finite element two-phase model that is able to predict the elastic moduli and the yield strength of nanostructured material as functions of their microstructure. The numerical methodology uses representative volume elements (RVEs) in which the material microstructure, i.e., the grains and grain boundaries, is presented utilizing the three-dimensional (3D) Voronoi algorithm. The implementation of the 3D Voronoi particles was performed on the nanostructure investigation of ultrafine materials by SEM and TEM. Proper material properties for the grain interiors (GI) and grain boundaries (GB) were computed using the Hall-Petch equation and a dislocation-based analytical approach, respectively. The numerical outcomes show that the Young’s Modulus of nanostructured copper increased by increasing the crystallite volume fraction, while the yield strength increased by decreasing the grain size. The numerical predictions were strongly confirmed in opposition to finite element outcomes, experimental results from the open literature, and predictions from the rule of mixtures and the Mori-Tanaka analytical models.

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The effect of grain size diversity on the flow stress of nanocrystalline metals by finite-element modelling

Cited by 19 publications

References 26 publications

The influence of an ECAP-based deformation process on the microstructure and properties of electrolytic tough pitch copper

The influence of an ECAP-based deformation process on the microstructure and properties of electrolytic tough pitch copper

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

Numerical Computation of Material Properties of Nanocrystalline Materials Utilizing Three-Dimensional Voronoi Models

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