Chelyabinsk, Russia

Chelyabinsk State University
Chelyabinsk, Russia

Chelyabinsk State University is a university in Chelyabinsk, Russia. It was established in 1976 and is considered one of the leading academic institutions in the south Urals. Wikipedia.

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Kuzmin D.A.,Chelyabinsk State University | Bychkov I.V.,Chelyabinsk State University | Shavrov V.G.,RAS Institute of Radio Engineering and Electronics
Optics Letters | Year: 2015

In the present work, change in speckle-pattern of linearly polarized light passed through graphene-covered optical fiber placed in external magnetic field is investigated. The possibility of magnetic speckle-pattern rotation suppression and inverse speckle-pattern rotation effect is shown. This effect can be controlled by a chemical potential of graphene layer, which can be changed easily by a gate voltage, for example. For quartz optical fiber at wavelength 0.633 μm, core diameter 9 μm, and fiber length 5 cm, an inverse rotation value of 17° is reached at chemical potential of graphene layer about 1 eV and magnetic field strength 30 kOe. Results of the work may be useful for different magneto-optics, opto-electronics, and photonics applications. © 2015 Optical Society of America.

Buchelnikov V.D.,Chelyabinsk State University | Sokolovskiy V.V.,Chelyabinsk State University
Physics of Metals and Metallography | Year: 2011

A review is given of experimental and theoretical works concerning the investigation of magnetic and structural phase transitions and of the magnetocaloric effect in Ni-Mn-X (X = Ga, In, Sn, Sb) Heusler alloys possessing unique properties, such as the existence of coupled magnetostructural and metamagneto-structural phase transitions, giant magnetocaloric effect, shape-memory effect in the ferromagnetic state, giant magnetodeformation and magnetoresistance, exchange anisotropy. A conclusion is made that the Heusler alloys, because of their unique properties, are promising for the application in various engineering devices, including technology of magnetic refrigeration. © Pleiades Publishing, Ltd., 2011.

Belenkov E.A.,Chelyabinsk State University | Greshnyakov V.A.,Chelyabinsk State University
Xinxing Tan Cailiao/New Carbon Materials | Year: 2013

New schemes of structural classification for carbon phases and nanostructures have been proposed, which are based on the types of chemical bonds formed and the numbers of the nearest neighbors with which each atom forms covalent bonds. The classification schemes can describe not only the known phases, but also new phases and nanostructures. New phases can be derived by linking, superpositioning or cutting precursor structures. The classification scheme has been used to predict diamond polymorphs, yielding thirty diamond-like phases that consist of atoms in equivalent crystallographic positions and eighteen of which were predicted for the first time.

Krasnikov V.S.,South Ural State University | Mayer A.E.,Chelyabinsk State University
Surface and Coatings Technology | Year: 2012

The effect of the Low Energy High Current Pulsed Electron Beam (LEHCPEB) and High Power Pulsed Ion Beam (HPPIB) surface treatment on the dislocation density in iron target has been numerically investigated. At typical technological irradiation parameters the major factors for modification of dislocation density are the thermo-stresses in the heat affected zone. Irradiation regimes, within the process of which there is no melting, generate one maximum of dislocation density, at the same time the regimes resulting in melting produce two maximums of dislocation density: one of them is localized inside the layer which has crystallized from melt, and the other one at the melt-solid interface. The increase of enclosed energy density and the reduction of pulse duration make the excited stress wave even more significant for the dislocation modification. This wave causes hardening of the material in deeper layers which may eventually result in the influence on the whole volume of the target. © 2012 Elsevier B.V.

Mayer A.E.,Chelyabinsk State University | Krasnikov V.S.,South Ural State University
Engineering Fracture Mechanics | Year: 2011

Ultra-short powerful electron beam is a suitable tool for producing of high rate deformation in substance. In paper we present a new model of high rate fracture and use this model for numerical investigation of fracture of copper target at irradiation by sub-nanosecond electron beam. In this model, fracture is considered as a time-dependent process of nucleation and growth of opening mode cracks. The nucleation and growth rates are controlled by specific free energy of crack surface which is sole fitted parameter. Plastic deformations, both in cracks vicinity and total in substance, are described in frames of dislocation theory. For verification of the model, we performed simulations of spall fracture at plate impact and at irradiation by high-current electron beam with pulse duration of tens of nanoseconds, and reasonable agreement with experimental data has been demonstrated. Simulations of the sub-nanosecond electron beam action on target indicate that spall fracture of the irradiated target surface is possible. This fracture takes place at the enclosed energy density slightly below the value, which is sufficient for melting of irradiated substance. Fracture threshold energy density does not depend on the origin dislocation density and it increases with the increase of pulse duration. As a result, at long pulse durations (more than ten nanoseconds) the substance melts before fracture. © 2011 Elsevier Ltd.

Krasnikov V.S.,South Ural State University | Mayer A.E.,Chelyabinsk State University | Yalovets A.P.,South Ural State University
International Journal of Plasticity | Year: 2011

This paper focuses on the development of a plasticity model to describe high rate deformations of metals. Modeling of target mechanical response is performed in frames of continuum mechanics. Plastic flow is described as the result of an over barrier dislocation sliding in specific slip planes. Computations of shock wave propagation in fcc, bcc and hcp metals modeling in comparison with shock wave experiments are performed to verify the model. The model predicts yield strength increase on elastic precursor in aluminum monocrystal and titanium of high purity at high temperatures. The action on a copper target of the electron beams with energy density (the total energy incident on an unit area during an irradiation pulse) 8.6 J cm-2 and varied pulse duration has been investigated. At the considered irradiation regime the target remains in a solid state (maximal temperature is 710 K) and shear stresses can reach values of about 0.72 GPa. Depth distribution of dislocation density after irradiation has a maximum that is localized on a distance of 10 μm from the irradiated surface and the maximum dislocation density is about 6 × 109 cm-2 in the target. The shortening of the exposure time to 1 ns leads to the increase of the dislocation density. Further reduction of exposure time has a weak effect on the dislocation density because the shear stresses reach a limit. © 2011 Elsevier Ltd. All rights reserved.

Mayer A.E.,Chelyabinsk State University | Borodin E.N.,Chelyabinsk State University | Mayer P.N.,Chelyabinsk State University
International Journal of Plasticity | Year: 2013

This study numerically investigates the influence of the initial perturbations of temperature or dislocation density in metals and of the stress concentrators on the plastic flow localization. The high-rate simple shear of micro-sample is simulated in two-dimensional formulation with use of the continuum mechanics and the dislocation plasticity model. The calculations are performed for the pure aluminum and the aluminum alloy, which differ by the yield stress values and by its temperature dependences. The considered perturbations of temperature or dislocation density lead to restricted localization of the plastic deformation, but they cannot initiate instability of the plastic flow as a self-sustained and increasing process. The more effective reason of the localization is the stress concentration, caused, for example, by boundary conditions. The plastic deformation rate is maximal in the shear stress localization areas and it can be close to zero outside these areas. Analytical estimation of the localization degree is constructed, which is in qualitative agreement with the numerical data; this estimation reveals that the localization degree grows linearly with time at the constant strain rate. © 2013 Elsevier Ltd. All rights reserved.

Belenkov E.A.,Chelyabinsk State University | Greshnyakov V.A.,Chelyabinsk State University
Journal of Experimental and Theoretical Physics | Year: 2014

The structural characteristics and properties of three new carbon phases (LA9, LA10, CA12), which have a diamond-like structure and atoms located in crystallographically equivalent positions, are described. The model mechanism of LA9 and LA10 formation is the linking of L6 and L4-8 graphene layers, respectively, and phase CA12 can be formed by linking C 4 tetrahedral clusters. Phases LA9, LA10, and CA12 can also be formed as a result of the polymorphic transformations of three-dimensional graphite phases, when all atoms transform from a three-coordinated into a four-coordinated state. LDA-DFT calculations of the LA9, LA10, and CA12 phases are used to find their geometrically optimized structures and properties (density, total energy, density of states). In addition, powder X-ray diffraction patterns are calculated for these phases and possible methods of their synthesis are analyzed. © 2014 Pleiades Publishing, Inc.

Belenkov E.A.,Chelyabinsk State University | Greshnyakov V.A.,Chelyabinsk State University
Physics of the Solid State | Year: 2013

New schemes have been proposed for the structural classification of carbon phases and nanostructures. These schemes are based on the types of chemical bonds formed in materials and on the number of nearest neighbors with which each atom forms covalent bonds. The classification schemes allow one to describe the already known phases and form the methodological basis for the prediction of new phases and nanostructures. © 2013 Pleiades Publishing, Ltd.

Nikolaychuk P.A.,Chelyabinsk State University
Journal of Chemical Education | Year: 2014

Clarification is provided regarding the third axis in E-pH-M diagram. The other variants of three-dimensional Pourbaix diagram are proposed. © 2014 The American Chemical Society and Division of Chemical Education, Inc.

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