Effect of Ultrasonic Treatment on the Microstructure and Properties of Nanostructured Nickel Processed by High Pressure Torsion

Nazarova, A. A.; Mulyukov, R. R.; Tsarenko, Yuriy; Рубаник, В. В.; Назаров, А. А.

doi:10.4028/www.scientific.net/msf.667-669.605

Cited by 8 publications

(7 citation statements)

References 7 publications

(6 reference statements)

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“…This work allowed one to predict many qualitative effects related to UST such as the relaxation of GBs, internal strains, and increase of the fraction of high-angles boundaries. All these predictions are confirmed by experimental data presented in [20,24,25].…”

Section: Relaxation Of Nonequilibrium Grain Boundaries Induced By Cycsupporting

confidence: 82%

“…In the first study [20] it was shown that oscillating tension-compression stresses with amplitudes in the range 40 ÷ 140 MPa resulted in a decrease of microhardness, rms microstrain, notable increase of the thermal stability of microstructure in nanostructured Ni processed by HPT. Structural studies showed that GBs changed their diffraction contrast as in the case of moderate annealing, i.e.…”

Section: Relaxation Of Nonequilibrium Grain Boundaries Induced By Cycmentioning

confidence: 99%

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Nonequilibrium grain boundaries in bulk nanostructured metals and their recovery under the influences of heating and cyclic deformation. Review

Назаров¹

2018

LoM

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Bulk nanostructured, or ultrafine-grained (UFG) metals and alloys produced by severe plastic deformation (SPD) methods have grain boundaries (GBs), which are in a specific, non-equilibrium state associated with extrinsic grain boundary dislocations (EGBDs) introduced into the boundaries during deformation. In the present review, the origin of this state is analyzed basing on the results of studies of large plastic deformations, according to which during straining the GBs accumulate mesodefects consisting of Rybin disclinations at triple junctions and tangential EGBD arrays and inherit them after removing the load. The main experimental evidences of the nonequilibrium character of GBs in as-prepared nanostructured materials are presented. Main ideas and results of the structural model of UFG metals based on the physics of dislocations and disclinations are overviewed. The latest works on molecular dynamics simulations carried out to explore the detailed atomic structure of disclinations and nonequilibrium GBs are considered and their results are compared to the predictions of the structural model. Mechanisms and kinetics of diffusion controlled recovery of nonequilirium GBs are described. An alternative mechanism of athermal relaxation of nonequilirium GB structure under the action of oscillating stresses has been most recently discovered and elucidated experimentally and by means of computer simulations. The main results of these studies are shortly reviewed too.

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Section: Relaxation Of Nonequilibrium Grain Boundaries Induced By Cycsupporting

confidence: 82%

Section: Relaxation Of Nonequilibrium Grain Boundaries Induced By Cycmentioning

confidence: 99%

Nonequilibrium grain boundaries in bulk nanostructured metals and their recovery under the influences of heating and cyclic deformation. Review

Назаров¹

2018

LoM

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“…The maximum USV action also results in a decrease in the CSR value and microdistortions level, which indicates that a more equilibrium structural state is produced under these conditions. A reduction in the density of free dislocations in the material, both during and after deformation, is very typical for the application of USV, as reported, for example, in the previous papers [5][6][7][8][9][10].…”

Section: Discussionmentioning

confidence: 75%

“…In the works dealing with the deformation of Ni with subsequent ultrasonic treatment, there is also observed a tendency for reduction of the microstresses of the matrix and for relaxation of the dislocation structure, and it is also important to note that the size of the fragments remains fixed [5,7]. In a comprehensive work studying the effect of USV in the process of deformation of aluminium, a decrease in the force parameters of the process is noted [22].…”

Section: Discussionmentioning

confidence: 99%

“…Numerous research works have revealed the effect of ultrasonic vibrations (USV) on the mechanical and physical properties of metals under different types of loading [1][2][3][4]. As shown in [5][6][7][8][9][10], USV have an effect primarily on dislocation motion and dislocation ensembles. Edge dislocations under the USV action climb to grain boundaries and the antinodal region of the forming standing wave [6].…”

Section: Introductionmentioning

confidence: 99%

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Ultrasound effect on structure and properties of Cu–0.5Cr under upsetting

Donic

Рааб

Аксенов

et al. 2020

Materials Science and Technology

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We studied the effect of the regimes of ultrasonic action on the structural transformation during free upsetting with 50% reduction of the copper alloy Cu–0.5Cr. In the process of deformation, the samples were subjected to intermittent and continuous ultrasonic actions. It can be noted that the application of ultrasonic vibrations in the process of deformation leads in both cases to a reduction in yield strength. Under a continuous ultrasonic action with a power of 640 W, the most developed structure is formed, with a fraction of high-angle boundaries equal to 32.4%, with the lowest values of coherent scattering regions, density of dislocations and microdistortions, while the decline in yield strength of the material under deformation is 40 MPa. This paper is part of a Thematic Issue on Copper and its Alloys.

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A double-gaussian waveguide for ultrasonic treatment of metals

Mukhametgalina

Назаров

2019

Lett. Mater.

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Ultrasonic treatment (UST) of metals is based on the exciting of resonant high-frequency vibrations to induce oscillating elastic stresses in the bulk of materials, which result in the generation, motion and rearrangement of crystal lattice defects. Normally, the resonant vibrations are obtained by using cylindrical samples or ultrasonic instruments having the length equal to the half-wavelength of ultrasound. In such waveguides, however, the distribution of the stress amplitude is not uniform along their axis. Accordingly, changes in the structure and properties due to the UST are different along the sample. Here, a new type of ultrasonic waveguide based on the Gaussian (ampulla) horn is proposed and called a double-Gaussian waveguide. It is composed of two identical high-amplitude parts of a Gaussian waveguide joined at a node that allows one to achieve a uniform distribution of the amplitude of normal stresses in a significant region with a length equal to that of a doubled Gaussian region. Analytic results obtained by Eisner are used to calculate geometrical characteristics of the waveguide and the latter are refined by finite element modeling. Characteristics of double-Gaussian waveguides made of steel 45 and titanium alloy VT6 (Russian grades) are calculated. This type of waveguide can be used in the bulk ultrasonic treatment of materials to expose the samples to oscillating stresses of an equal amplitude.

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Effect of Ultrasonic Treatment on the Microstructure and Properties of Nanostructured Nickel Processed by High Pressure Torsion

Cited by 8 publications

References 7 publications

Nonequilibrium grain boundaries in bulk nanostructured metals and their recovery under the influences of heating and cyclic deformation. Review

Nonequilibrium grain boundaries in bulk nanostructured metals and their recovery under the influences of heating and cyclic deformation. Review

Ultrasound effect on structure and properties of Cu–0.5Cr under upsetting

A double-gaussian waveguide for ultrasonic treatment of metals

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