Papers by Author: Vladimir Fesenko

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Authors: Yuriy Perlovich, M. Grekhov, Margarita Isaenkova, Vladimir Fesenko, B. Kalin, V. Yakushin
Abstract: Irradiation of metal materials with low-energy ions is accompanied by the long-range effect, consisting in distinct texture and structure changes at the depth, exceeding, at least, by 104 times the thickness of the layer of ion retardation. In order to ascertain mechanisms of this effect, a layer-by-layer X-ray study was carried out as applied to ion-plasma treated cladding tubes of Zr- 1%Nb alloy for nuclear reactors. Impacts of pulse treatments with helium plasma by two different regimes and the ion energy of ~ 1 keV were compared. It was found, that only by minimal surface melting the ion-plasma treatment causes unpredictable bulk texture changes, consisting in arising of the axial texture component. The melted surface layer suppresses shock waves, associated with braking of ions and supposedly responsible for stimulation of dislocation processes at long distances from the surface.
Authors: Margarita Isaenkova, Yuriy Perlovich, Vladimir Fesenko, Olga Krymskaya
Abstract: Possibilities of X-ray methods, using diffractometric measurements of X-ray line profiles and crystallographic texture, are compared as applied to study of SPD metal materials. The texture analysis gives the most direct data on the degree of grain fragmentation under conditions of deformation. The consideration is illustrated by results, obtained by X-ray studies of ECAP rods from Cu and Ti.
Authors: Yuriy Perlovich, Margarita Isaenkova, Vladimir Fesenko, Hans Joachim Bunge
Abstract: The substructure nonuniformity of metal materials with developed deformation texture was studied by use of the X-ray method of Generalized Pole Figures. Main regularities of substructure nonuniformity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct cross-wise system, consisting in alternation of quadrants with predominant microstrains of opposite signs.
Authors: Margarita Isaenkova, Yuriy Perlovich, Vladimir Fesenko, M. Grekhov
Abstract: By taking into account an interconnection between substructure non-uniformity and substructure anisotropy, a new approach to study the substructure non-uniformity is developed as applied to metal rods, subjected to Equal-Channel Angular Pressing (ECAP). The X-ray method of Generalized Pole Figures (GPF) was used for construction of distributions of substructure parameters. Some experimental data are presented, illustrating possibilities and efficiency of the used approach.
Authors: Yuriy Perlovich, Margarita Isaenkova, Vladimir Fesenko, Tatyana Dementyeva
Abstract: Typical modes of the microstress distribution were found by X-ray study of Ti-Ni rolled single crystals using the X-ray method of Generalized Pole Figures. The method consists in successive measurements of the peak position 2θ for the same X-ray line of B2 phase by all possible positions of the sample in the course of diffractometric study of its texture. In the case of one-component rolling texture maxima in pole figure break into halves with opposite signs of elastic deformation, whereas by two-component rolling textures the one-sign elastic strain dominates within different maxima.
Authors: Yuriy Perlovich, Margarita Isaenkova, Hans Joachim Bunge, Vladimir Fesenko
Authors: Yuriy Perlovich, Margarita Isaenkova, Olga Krymskaya, Vladimir Fesenko
Abstract: The method was developed for quantitative estimation of inputs to plastic deformation of crystallographic and non-crystallographic modes of slip by data of X-ray texture measurements. The texture analysis allows to split material into fractions, deformed by predominant operation of crystallographic and non-crystallographic mechanisms, differing in final orientations of grains. Whereas texture maxima in pole figures correspond to grains, deformed by means of crystallographic slip and having predictable final orientations, texture minima are formed by grains, whose deformation does not submit to crystallographic regularities and therefore their orientations are deflected from stable positions or even prove to be arbitrary. These effects are demonstrated as applied to semi-products from Zr-based alloys, subjected to the deformation treatment at temperatures of the (α+β)-region of Zr-Nb phase diagram.
Authors: Margarita Isaenkova, Yuriy Perlovich, Vladimir Fesenko, Olga Krymskaya, Alexander Zavodchikov
Abstract: The deformation behavior of commercial Zr alloys with 1% and 2,5%Nb under compression at temperatures of the (α+β)-region of Zr-Nb phase diagram is considered on the basis of experimental data obtained by X-ray texture study of deformed samples. Mechanisms, responsible for plastic deformation of alloys by different temperature-rate regimes were determined on the basis of resulting textures. Among these mechanisms there are crystallographic slip and mutual displacements of crystallites along interphase boundaries. The latter mechanism sharply intensifies by grain fragmentation down to nanostructuring under conditions of α«β phase transformations. Texture features of deformed samples testify about interaction of plastic deformation with phase transformations and indicate that due to this interaction compression by optimal regimes promotes the utmost refinement of structure elements.
Authors: Yuriy Perlovich, Margarita Isaenkova, Vladimir Fesenko, M. Grekhov, Seng Ho Yu, Sun Keun Hwang, Dong Hyuk Shin
Abstract: A detailed X-ray study of Zr rods, subjected to ECAP at 350oC by routes C and BC, was conducted by the new X-ray method of Generalized Pole Figures, combining texture measurement with registration of X-ray line profiles. The data analysis is based on conceptions of the texture formation theory, connecting features of grain reorientation with activated deformation mechanisms. A degree of reproduction of the same distinctive texture by successive ECAP passes with antecedent rotation of the rod reflects attendant structure changes in material.
Authors: Yuriy Perlovich, Margarita Isaenkova, M. Grekhov, Olga Krymskaya, Vladimir Fesenko, S. Zavodchikov, V. Kotrekhov
Abstract: Distinctive structure features of rods produced by hot and cold radial forging of a Zr- 2.5%Nb alloy were revealed. Most experimental data were obtained by X-ray methods. Among considered aspects, connected with the undulatory mechanism of energy transfer, there are the uniformity of bulk deformation, structure perfection under hot radial forging, the demolition of secondary phases and the oversaturation of α-Zr with Nb under cold radial forging, the role of phase transformations in deformation, and the suppression of recrystallization by annealing. Structure, texture and properties of products, produced by radial forging from Zr-based alloys, allow to consider this technology as an acceptable alternative to that usable nowadays.
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