Papers by Author: Margarita Isaenkova

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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: Olga Krymskaya, Margarita Isaenkova, Yuriy Perlovich
Abstract: The method for grain size determination by statistical fluctuations of X-ray intensity, registered during measurement of texture pole figures, was developed. Niobium and bronze rods as well as tubes from Zr-1%Nb alloy, subjected to annealing at different temperatures, were studied. Description of the method, pole figures (PF), X-ray intensity distribution within PF circular sections, grain size values and their errors are presented.
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: Margarita Isaenkova, Yuriy Perlovich
Abstract: As applied to tubes from Zr-based alloys, the X-ray method was developed to determine the dislocation density distribution in a-Zr depending on the orientation of Burgers vector. The method consists in registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in generalized pole figures. Obtained data testify that the dislocation density varies within very wide intervals of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the constructed dislocation distributions are closely related to the crystallographic texture of studied tubes.
Authors: Yuriy Perlovich, Margarita Isaenkova, Evgeniy Zharikov, Olga Krymskaya
Abstract: The X-ray method of Generalized Pole Figures was used by study of residual deformation effects in steel shell tubes for high-temperature atomic reactor. Ferritic-martensitic steel contained disperse strengthening oxide particles and their behavior under technological treatment was of essential practical interest. The used procedure estimates residual deformation effects in grains with different orientations and depicts distributions of elastic lattice distortion and interplanar spacings. Invisible oxide particles redistribute within the tube wall and strain hardening at its outer side is higher.
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
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