Enhanced Strength and Ductility of Ultrafine‐Grained Ti Processed by Severe Plastic Deformation

Semenova, Irina P.; Salimgareeva, Gulnaz; Costa, G. Da; Lefebvre, W.; Valiev, Ruslan Z.

doi:10.1002/adem.201000059

Cited by 98 publications

(72 citation statements)

References 28 publications

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“…Cu [110] and Ti, [111,112] or after HPT for Ta [113] and an Al-1% Mg alloy. [114] The principle of this approach is to equilibrate the grain boundaries after SPD without incurring any significant grain growth and thereby to move dislocations from the grain interiors to the grain boundaries so that strain hardening is increased leading to higher ductility.…”

Section: Observations On the Paradox Of Strength And Ductilitymentioning

confidence: 99%

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Balasubramanian

Langdon

2016

Metall Mater Trans A

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Metals processed by severe plastic deformation [SPD] techniques, such as equal-channel angular pressing [ECAP] and high-pressure torsion [HPT], generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the HallPetch [H-P] relationship. Examples of this behavior are discussed using data on Ti, Al-Mg 1 and Ni. These materials typically have grain size above ~50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. High strength and ductility can be achieved simultaneously by imposing high strains to give both ultrafine grain sizes and a high fraction of high-angle grain boundaries. An example is presented for a cast Al-7% Si alloy processed by HPT. In some cases, SPD may produce a fine grain size but also lead to a weakening due to microstructural changes as in ECAP of an Al-7034 alloy and HPT of Zn-22% Al. In SPD-processed materials, grain boundary segregation and nanostructural features are present which may lead to higher strengths than those predicted by the H-P relationship in some alloys having nano grain sizes.

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Section: Observations On the Paradox Of Strength And Ductilitymentioning

confidence: 99%

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Balasubramanian

Langdon

2016

Metall Mater Trans A

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“…Estimates show that the contribution of the oxides to the flow stress of nanocrystalline Ti is marginal (~4.7 MPa). According to the work [10], the changes in the concentration of oxygen near boundaries can also considerably affect the strength and ductility of UFG Ti after annealing at 623 K. From this work, it appears that the changes in the concentration of alloying elements near grain boundaries and the accompanying grain boundary segregations with their influence on the plastic deformation response should be also investigated in more detail during further study.…”

Section: Resultsmentioning

confidence: 82%

“…For the past decade or so, the interest in the application of severe plastic deformation (SPD) techniques to manufacture nanostructured Ti has been motivated by several factors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. First, the reports on the formation of an ultrafine-grained structure from SPD processing and its influence on the mechanical behavior have led to interesting fundamental questions [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…First, the reports on the formation of an ultrafine-grained structure from SPD processing and its influence on the mechanical behavior have led to interesting fundamental questions [1][2][3][4][5][6][7][8][9][10][11][12][13]. Second, the published studies suggest that nanostructuring of Ti and its alloys can result in significant enhancements in strength, ductility and fatigue life [10,14], which provide a pathway to the structural and medical applications.…”

Section: Introductionmentioning

confidence: 99%

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Nanocrystalline Ti Produced by Cryomilling and Consolidation by Severe Plastic Deformation

Semenova

Timokhina

Исламгалиев

et al. 2015

Metals

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Abstract:We report on a study of the nanocrystalline structure in Ti, which was produced by cryogenic milling followed by subsequent consolidation via severe plastic deformation using high pressure torsion. The mechanisms that are believed to be responsible for the formation of grains smaller than 40 nm are discussed and the influence of structural characteristics, such as nanometric grains and oxide nanoparticles, on Ti hardening is established.

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“…One of the interesting solutions of the materials property enhancement lies in the concept of non-equilibrium grain boundaries (NEGB) [87]. Recently, several works appeared which show that the mechanical properties of nanomaterials can be potentially improved by using non-equilibrium state of the grain boundaries [87,[90][91].…”

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

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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Enhanced Strength and Ductility of Ultrafine‐Grained Ti Processed by Severe Plastic Deformation

Cited by 98 publications

References 28 publications

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Nanocrystalline Ti Produced by Cryomilling and Consolidation by Severe Plastic Deformation

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

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