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Kolobov, Yu. R.; Grabovetskaya, G. P.; Ivanov, K. V.; Иванов, М. Б.

doi:10.1023/a:1015128928158

Cited by 74 publications

(41 citation statements)

References 7 publications

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“…First direct measurements of grain boundary diffusion in severely deformed materials yielded ambiguous results -both similar [113] and enhanced [114][115][116] rates of atomic transport were deduced with respect to the grain boundary diffusivities in reference coarse-grained materials.…”

Section: Diffusion Along Grain Boundaries In Ultrafine Grained Materialsmentioning

confidence: 99%

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

Sauvage

Wilde

Divinski

et al. 2012

Materials Science and Engineering: A

476

219

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Grain boundaries in ultrafine grained (UFG) materials processed by severe plastic deformation (SPD) are often called "non-equilibrium" grain boundaries. Such boundaries are characterized by excess grain boundary energy, presence of long range elastic stresses and enhanced free volumes. These features and related phenomena (diffusion, segregation, etc.) have been the object of intense studies and the obtained results provide convincing evidence of the importance of a non-equilibrium state of high angle grain boundaries for UFG materials with unusual properties. The aims of the present paper are first to give a short overview of this research field and then to consider tangled, yet unclear issues and outline the ways of oncoming studies. A special emphasis is given on the specific structure of grain boundaries in ultrafine grained materials processed by SPD, on grain boundary segregation, on interfacial mixing linked to heterophase boundaries and on grain boundary diffusion. The connection between these unique features and the mechanical properties or the thermal stability of the ultrafine grained alloys is also discussed.

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Section: Diffusion Along Grain Boundaries In Ultrafine Grained Materialsmentioning

confidence: 99%

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

Sauvage

Wilde

Divinski

et al. 2012

Materials Science and Engineering: A

476

219

View full text Add to dashboard Cite

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“…First direct measurements of grain boundary diffusion in severely deformed materials yielded ambiguous resultsboth similar [23] and enhanced [24] rates of atomic transport were estimated with respect to the grain boundary diffusivities in reference coarse-grained material. Recent measurements by the radiotracer technique discovered a hierarchic nature of internal interfaces which are developing as a result of strong dislocation activity during SPD processing.…”

Section: Diffusion Characterizationmentioning

confidence: 99%

Plasticity and Grain Boundary Diffusion at Small Grain Sizes

et al. 2010

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Severe plastic deformation (SPD) processes have attracted considerable attention due to their potential for fabricating large quantities of material with an overall small grain size. [1,2] In the last decade, various SPD processes have been proposed for ultragrain refinement, such as high pressure torsion (HPT), [1] equal channel angular pressing (ECAP) [3] accumulative roll bonding (ARB) [4] or-for achieving the smallest grain sizes for pure metals through SPD-repeated cold rolling (RCR) [5,6] as attractive routes for fabricating bulk nanoand submicron-grained materials. With these approaches, high densities of lattice defects are introduced into the material, which, according to the general view, can then rearrange to attain a minimum energy configuration by forming a submicron cell/sub-grain structure that can evolve to a fine grained microstructure with large fractions of high angle grain boundaries (HAGBs) upon continued straining. It has been observed that materials with fine grain sizes that had been synthesized by such a severe deformation route, exhibit spectacular properties and property combinations, such as, e.g., a very high yield strength and high ductility at the same time, enhanced hydrogen storage capacity and enhanced hydrogen permeation velocity or combinations of high mechanical strength and high electrical conductivity, see, e.g., the recent overview in ref. [7] Along with the modification of the grain structure towards finer grains, the high number of lattice defects that are created led to the postulation of modifications of the grain boundary structure to explain the unusual (mechanical) properties that were observed. In the simplest description, high numberBulk nanostructured-or ultrafine-grained materials are often fabricated by severe plastic deformation to break down the grain size by dislocation accumulation. Underlying the often spectacular property enhancement that forms the basis for a wide range of potential applications is a modification of the volume fraction of the grain boundaries. Yet, along with the property enhancements, several important questions arise concerning the accommodation of external stresses if dislocation-based processes are not longer dominant at small grain sizes. One question concerns so-called ''non-equilibrium'' grain boundaries that have been postulated to form during severe deformation and that might be of importance not only for the property enhancement known already today, but also for spectacular applications in the context of, e.g., gas permeation or fast matter transport for self-repairing structures. This contribution addresses the underlying issues by combining quantitative microstructure analysis at high resolution with grain boundary diffusion measurements.758

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“…4 there was an alternation of growth and reduction of the microhardness. The maximum value of microhardness in the samples obtained by drawing at room temperature was lower than after drawing at 77 K, and it was obtained at higher values of e f .…”

Section: Mechanical and Electrical Propertiesmentioning

confidence: 95%

“…Consequently, a great interest in recent years has been caused by a new approach to improvement of the properties of titanium and other metals, associated with the creation of nanostructured state by severe plastic deformation (SPD) [1]. Formation of nanostructure in titanium leads to an increase of the tensile strength and fatigue limit under cyclic loading [4]. Furthermore, the creation of nanostructured state in titanium implants leads to acceleration of osteointegration processes [1].…”

Section: Introductionmentioning

confidence: 99%

Obtaining of pure nanostructured titanium for medicine by severe deformation at cryogenic temperatures

Kutniy¹,

Volchok

Kislyak

et al. 2011

Materialwissenschaft Werkst

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The purpose of this study was to obtain pure nanostructured titanium by drawing at cryogenic temperatures and to investigate its structural and mechanical properties. Titanium rods were obtained by severe plastic deformation under the scheme of upsetting-extrusion-drawing. Upsetting and extrusion were performed at 800 K, obtained rod was initially drawn at 300 K to diameter of 3.7 mm (degree of true strain e = 3.2). Further deformation of the finish drawing was performed at 77 K (liquid nitrogen) and at 300 K.Keywords: titanium / medical implants / plastic deformation / nanostructure / mechanical properties / Das Ziel dieser Arbeit war die Herstellung von reinem nanostrukturiertem Titan durch die Tiefzieh-Verformung bei kryogenen Temperaturen und die Untersuchung seiner strukturellen und mechanischen Eigenschaften. Titanproben (Stäbe) wurden durch die starke plastische Verformung beim Pressen-Extrusions-Tiefziehen hergestellt. Das Pressen und die Extrusion wurden bei 800 K durchgeführt, der erhaltene Stab wurde zuerst bei 300 K zu einem Durchmesser von 3,7 mm gezogen (wahre Dehnung e = 3,2%). Eine weitere endgültige Verformung wurde durch Tiefziehen bei 77 K (flüssiger Stickstoff) und bei 300 K durchgeführt.

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Cited by 74 publications

References 7 publications

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

Plasticity and Grain Boundary Diffusion at Small Grain Sizes

Obtaining of pure nanostructured titanium for medicine by severe deformation at cryogenic temperatures

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