Персона: Исаенкова, Маргарита Геннадьевна
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Руководитель научной группы "Лаборатория рентгеновского текстурного анализа"
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Исаенкова
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Маргарита Геннадьевна
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- ПубликацияОткрытый доступТермическая стойкость сталей с повышенными характеристиками прочности для корпусов перспективных реакторов ВВЭР различных проекто(2023) Мальцев, Д. А.; Крымская, Ольга Александровна; Исаенкова, Маргарита Геннадьевна; Кулешова, Евгения Анатольевна; Федотов, Иван Владимирович; Минушкин, Роман АлександровичРассмотрены результаты структурных исследований и механических испытаний после длительного теплового воздействия лабораторных плавок металлургически усовершенствованной стали 15Х2НМФА и стали с повышенным содержанием никеля, рассматриваемых в качестве материалов корпусов перспективных реакторов ВВЭР различных проектов. Показано, что как для усовершенствованной стали 15Х2НМФА, так и для высоконикелевой стали отсутствуют признаки зернограничного охрупчивания после проведения термообработки, провоцирующей охрупчивание, что связано с очень низкой зернограничной сегрегацией фосфора в исходном состоянии, обусловленной повышенной дисперсностью структуры, а также достаточно низким содержанием примесей. Кроме того, для усовершенствованной стали 15Х2НМФА не выявлено изменения предела текучести, что согласуется с результатами структурных исследований. Для высоконикелевой стали в результате длительного теплового воздействия выявлена тенденция к небольшому снижению предела текучести на 5 – 10% и закономерному снижению критической температуры хрупкости. Снижение механических характеристик связано с относительно низкой температурой высокого отпуска высоконикелевой стали и, соответственно, возможным протеканием процессов доотпуска структуры при длительном тепловом воздействии, о чем свидетельствуют результаты рентгеноструктурных исследований. Несмотря на протекание процессов доотпуска в высоконикелевой стали при длительном тепловом воздействии сохраняется стабильность основных упрочняющих карбидных фаз, за счет чего предел текучести остается на достаточно высоком уровне, превышающем значения для используемых сталей корпусов реакторов ВВЭР даже при тепловом воздействии с параметрами, значительно превосходящими предполагаемые условия эксплуатации корпусов перспективных ВВЭР. При этом снижение критической температуры хрупкости при тепловом воздействии лишь способствует повышению стойкости стали против хрупкого разрушения при эксплуатации.
- ПубликацияОткрытый доступThermal resistance of steels with increased strength properties for pressure vessels of advanced VVER reactors of various designs(2023) Maltsev, D. A.; Исаенкова, Маргарита Геннадьевна; Крымская, Ольга Александровна; Федотов, Иван Владимирович; Кулешова, Евгения Анатольевна; Минушкин, Роман Александрович; Kuleshova, E. A.; Fedotov, I. V.; Isaenkova, M. G.; Krymskaya, O. A.; Minushkin, R. A.The paper considers the results of structural studies and mechanical tests after a long-term thermal exposure of laboratory heats of the metallurgically improved 15Kh2NMFA steel and steel with an increased content of nickel considered as materials for the pressure vessels of advanced VVER-type reactors of various designs. It has been shown that, both for the improved 15Kh2NMFA steel and the high-nickel steel, there are no signs of grain boundary embrittlement after an segregation provoking embrittlement heat treatment. This is explained by the extremely low grain boundary segregation of phosphorus in the initial state caused by a high degree of the structure dispersity as well as by rather a low content of impurities. Besides, no changes have been found in the yield strength value for the improved 15Kh2NMFA steel, which agrees with the structure investigation results. For the high-nickel steel, a tendency towards a minor yield strength decrease by 5 to 10% and a regular reduction of the critical brittleness temperature has been revealed. A decrease in the mechanical properties has been caused by a relatively low temperature of tempering for the high-nickel steel and, accordingly, by the potential occurrence of the structure recovery during long-term thermal exposure, as evidenced by the results of an X-ray diffraction analysis. Despite the structure recovery in the high-nickel steel under the long-term thermal exposure, the main strengthening carbide phases remain stable. Due to this, the yield strength value remains at a relatively high level that exceeds the values for the modern VVER-type vessel steels, even in the case of a thermal exposure much in excess of the expected operating conditions for advanced VVER reactors. The observed decrease of critical brittleness temperature during the long-term thermal exposure contributes to an increase in the steel resistance to brittle fracture.
- ПубликацияТолько метаданныеEvolution of structure, crystallographic texture and mechanical properties in innovative titanium alloys during plastic deformation and heat treatment(2020) Medvedev, P. N.; Isaenkova, M. G.; Perlovich, Y. A.; Babich, Y. A.; Исаенкова, Маргарита Геннадьевна© 2020, "Ore and Metals" Publishing house. All rights reserved.Titanium alloys, in spite of their low density, are characterized by high mechanical strength, corrosion resistance, creep resistance at elevated temperatures, heat resistance and manufacturability. A further increase in operational characteristics necessitates the development of new alloys. The presence in alloys of alpha-titanium, that is their low-temperature modification, characterizing by anisotropy of a crystalline hexagonal close-packed structure, pre-determines the interest to predominant crystallographic orientations of grains in products. This work is devoted to the analysis of plastic deformation and heat treatment influence on the structure, crystallographic texture and mechanical properties of promising titanium alloys VT18U, VT41 and VT25U. The studied alloys belong to their different types: the first two ones are pseudo-α-alloys, and the last one — (α+β)-alloy. Sheet samples were subjected to hot rolling and subsequent heat treatment in order to identify the influence of technological parameters on the formation of phase state and crystallographic texture of the alloys. The structure and texture of materials were studied by metallographic and X-ray methods. The phase composition of alloys was determined and their texture was analyzed by constructing direct pole figures and restoring orientation distribution functions of grains. The measurement of mechanical properties was carried out using continuous indentation curves. As a result of the study, the basic regularities of crystallographic texture formation during hot rolling and subsequent phase transformations as applied to alloys of various types have been revealed. It was found that the main texture components of hot rolled sheets are {0001}15–20o ND-RD<112– L>, {110}<100> and {110}<0001>, the ratios between which depend on the type of alloy. The mechanisms that determine the formation of texture during hot rolling were established. The limits of variation of the integral texture parameters for hot-rolled titanium pseudo- and (α+β)-alloys have been revealed, and the an-isotropy coefficients of yield strengths for alloys with textures of different types have been calculated. The research was conducted under financial support of the State Program for elevation of competitiveness in the National Research Nuclear University "MEPHI" (Agreement No. 02.a03.21.0005).
- ПубликацияТолько метаданныеRegularities of Formation of Lattice Structures Fabricated by Selective Laser Melting of Powdered 03Kh16N15M3 Steel(2020) Dub, A. V.; Isaenkova, M. G.; Perlovich, Y. A.; Yudin, A. V.; Rubanov, A. E.; Zhuravlev, N. Y.; Saveliev, M. D.; Исаенкова, Маргарита Геннадьевна; Савельев, Максим Дмитриевич© 2020, Pleiades Publishing, Ltd.Abstract: This article discusses adjustment of processing modes of selective laser melting of powdered 03Kh16N15M3 steel allowing fabrication of lattice structures with steady parameters. On the basis of statistical analysis of sizes of cells, ribs, and nodes in cross section parallel to the growth direction of lattice structures of two sizes of ribs and voids (400 × 1000 and 300 × 600 μm), the process variables providing fabrication of items with the most stable sizes along the height of the structure have been determined. The sizes of the main elements of the lattice structure have been determined using a scanning electron microscope; the crystallographic texture and material structure have been determined using X-ray structural analysis. It has been determined that increase in laser power leads to increase in distortions in crystalline structure and decrease in the lattice constant of the material of lattice structures. The highest distortions of the structure have been detected in ribs of lattice structures as well as in items with smaller sizes of ribs and voids. The material of the considered lattice structures is characterized by axial texture, for which crystallographic axes <100> are oriented parallel to the growth direction. The degree of manifestation of the axial texture component depends on the laser power used for growing of lattice structures. The samples obtained by minimum radiation power are characterized by a scattered axial texture, which is dictated by an increase in the number of chaotically oriented grains with a simultaneous decrease in the bulk of strictly oriented columnar crystals, located mainly in the vicinity of the axis of the ribs of the lattice structure. The texture sharpness in lattice samples with voids of small size is higher than that in samples with voids of large size.
- ПубликацияТолько метаданныеAccounting for twinning when modelling plastic deformation of-zirconium(2020) Isaenkova, M. G.; Perlovich, Y. A.; Krymskaya, O. A.; Zhuk, D. I.; Исаенкова, Маргарита Геннадьевна; Крымская, Ольга Александровна© 2020, "Ore and Metals" Publishing house. All rights reserved.In this work, the process of deformation of zirconium, which is widely used in nuclear power plants, was investigated using crystal plasticity modeling. This approach allows analyzing of the reorientation of grains and studying the process of material structure changing: Splitting of grains due to the development of twinning and the formation of high-angle boundaries. DAMASK code was used for the numerical solution of problems. It is based on a mathematical method for solving systems of partial differential equations using fast Fourier transformation. The program has been developed for processing simulation data and reorientation of crystallite twins in which stresses exceed a certain critical level corresponding to this material. For verification of the created method, the data of rolling zirconium single crystal plates was used. These plates were cut using the spark method from a cylindrical single crystal of pure Zr obtained by solid-phase recrystallization. The qualitative correspondence of the modeled pole figures to the experimental ones was found. The efficiency of the created model of plastic deformation in the case of simultaneous activation of slip and twinning systems is demonstrated. The dependences of the distribution of contributions to the deformation of various slip and twinning systems on the degree of deformation during rolling are constructed. According to the simulation data, the share of twinning in texture reorientation is 87%. Moreover, 66% is the share of twinning systems of the type. At further stages, the influence of twins on the texture is rather small, in total for all systems ~ 5%.
- ПубликацияТолько метаданныеInfluence of technology of obtaining chromium coating on cladding tubes from zr – 1% Nb – (O, Fe) alloy on change of its structure during air oxidation at temperatures 400–1150°c(2020) Berlin, E. V.; Isaenkova, M. G.; Perlovich, Y. A.; Stolbov, S. D.; Klyukova, K. E.; Fesenko, V. A.; Исаенкова, Маргарита Геннадьевна; Фесенко, Владимир Александрович© 2020, "Ore and Metals" Publishing house. All rights reserved.This paper compares the corrosion behavior of two chromium coatings obtained by different technological conditions. Depending on the process characteristics of creating coatings, a different structure was formed, which characterized by different orientations and grain sizes. The main differences of the investigated coatings were as follows: coating No. 1 was 9–10 μm thick, characterized by 0.2 μm columnar crystals and {111} <112> strict orientation throughout its thickness; coating No. 2 had a thickness of 12–14 μm, the size of the columnar crystals was 0.5 μm and their orientation was {111} <112> and {100} <001>. The coatings also differed in the level of compressive tangential macrostresses on the outer surface: in the first one, 1000 MPa, and in the second, only 490 MPa, which indicated the possibility of cracks presence in it. The presence of cracks was confirmed by metallographic images. Oxidation of cladding tubes with chromium coatings was carried out by their annealing in air in the temperature range of 400–1150oC for 1 hour. As a result of electron microscopic study of over the cross section elements distribution of oxidized samples, the main differences in the coatings oxidation kinetics obtained in different modes were established. In the initial state, both coatings interact with the substrate without the formation of intermediate phases, the chromium layer is replaced by a layer of zirconium alloy. In both cases, the transition zone is 2–3 microns. After annealing in air at a temperature of 1100oC for 1 h, an intermetallic layer (Zr, Nb)Cr2 with a thickness of 2–3 μm is formed between the coating and the substrate. Intermetallide identified by synchrotron diffraction coating study. The first coating changes its thickness to 5–6 microns, while on the surface it is not possible to detect the oxide phase. In the case of the second coating oxidation, a 3–4 μm layer of the oxide phase is observed, easily identified by X-ray and electron microscopic methods, which leads to a reduction in the thickness of the chrome coating. The pore distribution is also interesting: in the case of the first coating, the pores are located at the boundary of the intermetallic and chrome layers, and in the case of the second coating, the pores are distributed over the cross section of the chromium layer and in the oxide layers. The oxide layer thickness from the inner surface of the cladding tube is about 250 microns. The chrome coating, in the absence of cracks in it, reliably protects the cladding tube from oxygen. In the absence of cracks in the chrome coating, it reliably protects the cladding tube from oxygen. The presence of pores is due to differences in the temperature expansion of layers consisting of different metals. The present work was carried out under Governmental Support of Competitive Growth Program of NRNU MEPhI (agreement No. 02.a03.21.0005).
- ПубликацияОткрытый доступALUMINIUM OXIDATION IN PLASMA OF ABNORMAL GLOW DISCHARGE(НИЯУ МИФИ, 2023) Pisarev, A. A.; Tarasyuk, G. M.; Borisyuk, P. V.; Isaenkova, M. G.; Lebedinskii, Yu. Yu.; Zaripova, M. M.; Исаенкова, Маргарита Геннадьевна; Писарев, Александр Александрович; Тарасюк, Григорий Михайлович; Борисюк, Петр Викторович; Лебединский, Юрий ЮрьевичAluminum oxide layers in all its various forms have become widespread due to the unique combination of properties that can be modified by varying the conditions of their growth. The alumina layer can either be applied to the substrate by chemical and physical methods or grown by oxidation. For practical purposes, layers of various thicknesses and structures are needed. The standard method for obtaining thick (of the order of 100-1000 nm) porous layer is electric arc anodization in weak electrolytes. The standard method for obtaining thin (about 10 nm) layers is thermal oxidation. Dense layers of intermediate thickness are difficult to obtain by such methods. There are few papers in the literature that investigate the possibility of obtaining oxide layers with a thickness of tens of nanometers by oxidizing aluminum in oxygen plasma [1-5]. The description of the kinetics of the oxidation process in those works was given on the basis of the assumption of the diffusion character of oxygen transfer from the surface into the interior of the metal. This approach is absolutely unsuitable for description the transport of oxygen and aluminum through the oxide layer, since both oxygen and aluminum in the oxide are in the form of ions, and an electric charge is formed on the surface of the dielectric facing the plasma, so that the transport of oxygen coming from the plasma must occur under by the action of an electric field in the oxide dielectric layer. In this work, experiments on plasma enhanced oxidation (PEO) were carried out on the oxidation of aluminum in the anomalous glow discharge oxygen plasma, which provides uniform treatment over the entire surface of samples of arbitrary shape. Also, a simple model was proposed for description of the oxidation kinetics, taking into account oxygen transport in the electric field.
- ПубликацияТолько метаданныеEffect of biaxial cyclic severe deformation on structure and properties of Ti-Ni alloys(2019) Komarov, V.; Khmelevskaya, I.; Karelin, R.; Prokoshkin, S.; Zaripova, M.; Isaenkova, M.; Исаенкова, Маргарита Геннадьевна© 2019 Elsevier B.V. In this work, biaxial cyclic severe deformation of Ti-50.0 at.% Ni shape memory alloy was performed using MaxStrain module of Gleeble system at 250 °C with ultimately high accumulated true strain of e = 11. The martensitic transformations, structure and crystallographic texture features were studied using DSC, X-ray diffractometry, and TEM from three mutually perpendicular sides. The maximum completely recoverable strain was determined by a thermomechanical method, and the hardness was measured. A true nanocrystalline structure with grain/subgrain size of 50 nm has been formed in bulk Ti-Ni samples for the first time. The resulting structure is crystallographically isotropic and provides the completely recoverable strain of 9.6% that exceeds the best result attained for bulk equiatomic Ti-Ni alloys. The texture factor in a combination with the structure factor contribute to the completely recoverable strain only until accumulated strain reaches e = 9.5 at higher deformation temperatures.
- ПубликацияТолько метаданныеFormation of Residual Stresses in the Surface Layers of Titanium Alloy Targets Irradiated with High-Current Pulsed Electron Beams(2019) Shulov, V. A.; Steshenko, I. G.; Teryaev, D. A.; Fesenko, V. A.; Perlovich, Y. A.; Isaenkova, M. G.; Исаенкова, Маргарита Геннадьевна© 2019, Pleiades Publishing, Ltd.Abstract: X-ray diffraction analysis, optical metallography, and transmission electron microscopy demonstrated that irradiation with high-current pulsed electron beams in the melting mode leads to formation of residual compressive stresses and a finely dispersed globular-lamellar microstructure (the α, α', and α'' plates being oriented parallel or nearly parallel to the surface) in the near-surface layer of samples of VT6 and VT8 alloys up to 20 μm thick. These phenomena are expected to increase the fatigue strength of the material during bending tests. Meanwhile, residual tensile stresses are formed on the surface of samples of VT9 alloy at any energy density of electron beams; vacuum annealing is required to remove these stresses.
- ПубликацияТолько метаданныеFeatures of nanostructure and functional properties formation in Ti-Ni shape memory alloys subjected to quasi-continuous equal channel angular pressing(2019) Khmelevskaya, I. Yu.; Karelin, R. D.; Prokoshkin, S. D.; Komarov, V. S.; Isaenkova, M. G.; Perlovich, Yu. A.; Fesenko, V. A.; Zaripova, M. M.; Исаенкова, Маргарита Геннадьевна; Фесенко, Владимир Александрович© Published under licence by IOP Publishing Ltd. Influence of various deformation regimes, included severe plastic deformation by multi-pass rolling, rotary forging and equal channel angular pressing (ECaP) in the normal and quasi-continuous modes, on the structure and properties of Ti-Ni shape memory alloys was studied and compared. Features of structure formation providing a combination of high functional properties were analyzed. Investigation of the texture development, depending on the ECAP regimes and post-deformation annealing, was made.