Научная группа: Лаборатория ионно-плазменной и ионно-пучковой обработки материалов (Кафедра №9 ИЯФиТ)
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Microstructural evolution in ODS-EUROFER steel caused by high-dose He ion implantations with systematic variation of implantation parameters
(2023) Emelyanova, O. V.; Gentils, A.; Borodin, V. A.; Dzhumaev, P. S.; Емельянова, Ольга Владимировна; Бородин, Владимир Алексеевич; Джумаев, Павел Сергеевич
The paper presents a detailed analysis of helium (He) bubble development in ODS-EUROFER steel caused by helium ion implantation in different regimes, with a particular attention to the role of the oxide nanoparticles in promoting the growth of He bubbles, helium accumulation and gas-driven swelling. The Transmission Electron Microscopy (TEM) characterization of steel samples implanted applying systematic variation of experimental parameters has allowed clarifying the trends of the bubble microstructure evolution depending on the implantation dose, flux, and sample temperature. It was found that in all investigated implantation regimes He bubbles formed both in the grain bulk and on various structural defects (dislocations, grain boundaries, oxide particles and carbide precipitates), but the sizes and densities of bubbles in different bubble populations were sensitive to particular irradiation conditions. In the majority of cases the main traps for implanted helium and the main contributors to the estimated swelling were bubbles associated with grain boundaries, though in some cases (high implantation dose or lower temperature) the bubbles in the grain bulk were competitive with the grain boundary bubble population. Oxide particles in ODS-EUROFER were found to be excellent nucleation sites for He bubbles and practically each observed particle hosted a single relatively large bubble, sometimes as large as the particle itself. However, the contribution of oxide-associated bubbles to the estimated swelling and He inventory was found to be minor as compared to other bubble populations because of a relatively low number density of nano-oxides. Comparison of ODS-EUROFER and EUROFER 97 samples implanted with He ions in identical regimes has demonstrated lower efficiency of ODS-EUROFER for accumulating implanted helium in bubbles and noticeably higher share of helium atoms trapped in the vacancy defects invisible by TEM.
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Bubble-to-void transition promoted by oxide nanoparticles in ODS-EUROFER steel ion implanted to high He content
(2021) Gentils, A.; Vladimirov, P. V.; Golovchanskiy, I. A.; Lindau, R.; Emelyanova, O.; Borodin, V. A.; Ganchenkova, M. G.; Dzhumaev, P. S.; Емельянова, Ольга Владимировна; Бородин, Владимир Алексеевич; Джумаев, Павел Сергеевич
© 2020The paper deals with a detailed study of He-filled cavity ensemble development in ODS-EUROFER steel implanted with 10 keV helium ions to a high peak concentration of 8.5 × 103 appm both with and without simultaneous irradiation with 4 MeV gold ions, which allowed us to strongly vary the ratios of dpa/He introduction. The subsequent transmission electron microscopy examination reveals excellent radiation stability of He-implanted sample in the single-beam implantation mode. In contrast, after the simultaneous dual-beam irradiation a bubble-to-void transition was observed for bubbles that were associated with yttria nanoparticles. The relative importance of different He bubble families observed in the He-implanted samples for the swelling accumulation is quantitatively assessed, emphasizing the potential risks of abrupt swelling acceleration in the case of bubble-to-void transition launched by nanoparticles. A model of bubble-to-void transition for gas bubbles associated with spherical second-phase particles is developed and used to rationalize experimental observations.
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Regularities of Changes in the Structure of Different Phases of Deformed Zirconium Alloys as a Result of Raising the Annealing Temperature According to Texture Analysis Data
(2023) Isaenkova, M.; Krymskaya, O.; Klyukova, K.; Bogomolova, A.; Kozlov, I.; Dzhumaev, P.; Fesenko, V.; Исаенкова, Маргарита Геннадьевна; Крымская, Ольга Александровна; Богомолова, Анастасия Владимировна; Козлов, Илья Владимирович; Джумаев, Павел Сергеевич; Фесенко, Владимир Александрович
Based on the data of synchrotron and electron microscopic studies of deformed and annealed Russian zirconium alloys, the possibility of analyzing the structural-phase state and crystallographic texture of individual phases has been demonstrated. A qualitative and quantitative phase analysis of deformed and annealed tubes made of Zr-Nb-(Sn-Fe-O) alloys was carried out using diffraction patterns obtained with synchrotron radiation. The main α-Zr phase and the following additional phases: β-Nb, β-Zr, and the Laves phase (intermetallic compound Zr(Nb,Fe)2), were found in the alloys. According to the results of texture analysis of all phases present in the alloy, the mechanisms of plastic deformation, recrystallization, and phase transformations of the main and additional phases were established. It is shown that during plastic deformation of the Zr-1%Nb alloy, a dynamic phase transformation β-Nb→α-Zr→β-Zr is observed. It is established that during recrystallization, larger grains of α-Zr are misoriented relative to the deformed matrix by rotating the prismatic axes around the basal axes by 30°, while fine grains are improved by polygonization and maintain the orientation of the deformed matrix. Processes for changing the orientation of grains of additional phases as a result of high-temperature annealing are also considered.
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Josephson current mediated by ballistic topological states in Bi2Te2.3Se0.7 single nanocrystals
(2020) Stolyarov, V. S.; Yakovlev, D. S.; Kozlov, S. N.; Skryabina, O. V.; Emelyanova, O. V.; Dzhumaev, P. S.; Емельянова, Ольга Владимировна; Джумаев, Павел Сергеевич
© 2020, The Author(s).Superconducting proximity devices using low-dimensional semiconducting elements enable a ballistic regime in the proximity transport. The use of topological insulators in such devices is considered promising owing to the peculiar transport properties these materials offer, as well the hope of inducing topological superconductivity and Majorana phenomena via proximity effects. Here we demonstrate the fabrication and superconducting properties of proximity Josephson devices integrating nanocrystals single of Bi2Te2.3Se0.7 with a thickness of a few unit cells. Single junctions display typical characteristics of planar Josephson devices; junctions integrating two nanocrystals behave as nanodimensional superconducting quantum interference devices. A peculiar temperature and magnetic field evolution of the Josephson current along with the observed excess current effect point towards the ballistic proximity regime of topological channels. This suggests the proposed devices are promising for testing topological superconducting phenomena in two-dimensions.
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Joining tungsten with steel for DEMO: Simultaneous brazing by Cu-Ti amorphous foils and heat treatment
(2021) Svetogorov, R.; Bachurina, D.; Suchkov, A.; Gurova, J.; Savelyev, M.; Dzhumaev, P.; Kozlov, I.; Leont'eva-Smirnova, M.; Sevryukov, O.; Сучков, Алексей Николаевич; Гурова, Юлия Александровна; Савельев, Максим Дмитриевич; Джумаев, Павел Сергеевич; Козлов, Илья Владимирович; Леонтьева-Смирнова, Мария Владимировна; Севрюков, Олег Николаевич
© 2020Development of a reliable technology to join tungsten with steel is essential for DEMO application; however, it is difficult due to large differences in their physical properties. To solve this problem, high-temperature brazing was carried out. Cu-Ti brazing alloys, which were rapidly solidified into foil, were used together with a compensating vanadium interlayer, so the EK-181 steel/Cu-28Ti/V/Cu-50Ti/W and EK-181/Cu-50Ti/V/Cu-50Ti/W brazed joints were obtained. The microstructures of the seams were investigated by optical microscopy, SEM (EDX, EBSD) and synchrotron XRD. Thermocycling and shear strength tests showed that Cu-28Ti wt. % brazing alloy ensures a firmer joint compared to Cu-50Ti wt. %. The Cu-28Ti wt. % brazing alloy was used to perform high-temperature brazing in the brazing mode equivalent to traditional EK-181 steel heat treatment. It showed that every step of the heat treatment affected the microstructures and the shear strength.
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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.
Описание
Направления исследований:
- Разработка новых методов
Разработка методов и методик модифицирования наружной и внутренней поверхности твэльных труб для тепловыделяющих сборок реакторов на тепловых и быстрых нейтронах
-- Разработка хромосодержащих покрытий
Создание и исследование хромосодержащих покрытий на оболочках твэлов из сплава Э110о.ч., обеспечивающих повышение стойкости в условиях высокотемпературного окисления
- Исследования структурно-фазового состояния конструкционных материалов
Электронно-микроскопические исследования структурно-фазового состояния конструкционных материалов, включая сплавы на основе циркония, аморфные и наноструктурные материалы, высокоэнтропийные сплавы, коррозионностойкие стали систем Fe-Cr-Ni, Fe-Cr и другие сплавы
- Разработка передовых керамических покрытий
Разработка и нанесение керамических защитных покрытий, включая высокоэнтропийные карбидные керамики и MAX-фазы, для конструкционных материалов ядерной и аэрокосмической техники