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.

2022, Bobyr, N., Kulikova, E., Gasparyan, Y., Bachurina, D., Efimov, V., Gurova, J., Podolyako, F., Sergeev, N. S., Sorokin, I. A., Suchkov, A., Kozlov, I., Spitsyn, A. V., Гаспарян, Юрий Микаэлович, Ефимов, Виталий Сергеевич, Гурова, Юлия Александровна, Подоляко, Федор Сергеевич, Сергеев, Никита Сергеевич, Сорокин, Иван Александрович, Сучков, Алексей Николаевич, Козлов, Илья Владимирович

© 2022 Elsevier B.V.The fully reduced activation brazing alloy TiZr4Be and a tantalum intermediate layer are considered to be used for joining tungsten (W) to reduced-activation ferritic-martensitic steel (RAFM) for future DEMO reactor application. Deuterium retention in the W-Rusfer joints and separate elements was investigated with the focus on the intermediate brazing layer. The samples were exposed in deuterium gas (p = 1–104 Pa, T = 300–600°C) and plasma discharge (T = 600°C). An acceptable deuterium concentration was observed after gas exposure at the pressure of 1 Pa, that is relevant to operating conditions of future fusion devices, however the brazing alloy and tantalum accumulate a large amount of deuterium in the case of the pressure above 100 Pa that leads to failure of the joint. The D retention after D plasma irradiation was substantial, but nearly independent on the fluence and the thickness of the W layer due to absorption from surrounding D2 gas.

2021, Sliva, A., Svetogorov, R., Fedotov, I., Suchkov, A., Dzhumaev, P., Kozlov, I., Sevryukov, O., Федотов, Иван Владимирович, Сучков, Алексей Николаевич, Джумаев, Павел Сергеевич, Козлов, Илья Владимирович, Севрюков, Олег Николаевич

© 2021 The Society of Manufacturing EngineersIn this work, two molybdenum-graphite X-ray targets for computed tomography/angiography devices were manufactured with usage of Ti-40Zr-8.5Nb-1.5Be filler metal and 1400 °C – 20 min brazing mode. To confirm the efficiency of the proposed brazing method, a mechanical test and simulated heating of the anodes were carried out, as well as a study of the evolution of the brazed joint under operating conditions. The brazed joint of the anodes showed stability and maintained integrity after tests. However, it is revealed that the long-term heat treatment of the brazed Mo/graphite joint leads to an increase in the amount of carbides in the seam, and also converts the seam into a refractory state by suppressing the formation of beryllium eutectic, while the cyclic heating mainly affects the recrystallization of the seam phases, leading to phase fragmentation. Shear strength tests after simulated heating show that the failure of the Mo/graphite joint occurs in the graphite element with cracking due to the infiltration of the filler metal into graphite through the open porosity. Infiltrates could provoke the occurrence of stresses during cyclic heating/cooling because of the difference in the CTE of graphite and carbide phases. Nevertheless, the joints remained integrity and showed a minimal strength of 23.4 ± 2.5 MPa (after 20 heating cycles of 350 ↔ 1400 °C) and 26.1 ± 6.4 MPa (after vacuum annealing of 1400 °C – 8 h).

2021, Sliva, A., Svetogorov, R., Fedotov, I., Suchkov, A., Dzhumaev, P., Kozlov, I., Bachurina, D., Sevryukov, O., Федотов, Иван Владимирович, Сучков, Алексей Николаевич, Джумаев, Павел Сергеевич, Козлов, Илья Владимирович, Севрюков, Олег Николаевич

© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.The aim of this work was to braze molybdenum and graphite with Ti–40Zr–8.5Nb–1.5Be filler metal in order to demonstrate the possibility of its application for X-ray tube target brazing, further to investigate the joint microstructure using energy-dispersive X-ray spectroscopy (EDS), electron backscattered diffraction (EBSD), X-ray diffraction (XRD), and electron microscopy as well as to conduct shear and unbrazing tests. It is shown that the brazed joint consists of matrix from β-(Ti, Mo) solid solution, mixed ZrC and TiC carbide layers at the braze/graphite interface, and beryllides TiBe2 and MoBe2 located at the grain boundaries of β-(Ti, Mo). The presented data made it possible to propose a brazed joint formation mechanism and explain the concentration of beryllides at the grain boundaries during brazing, as well as the mixed carbide layer formation from the side of the graphite. The mechanical tests showed that Mo/graphite brazed joints have a shear strength of at least 28.0 ± 0.9 MPa. However, sample failure occurred through the graphite due to the graphite surface mechanical treatment and the presence of a ductile β-Ti phase in the joint. The evaluation of joint thermal properties was performed using unbrazing tests. The unbrazing temperature was 1882 °C, which was caused by formation of refractory phases during brazing. The microstructure study shows that unbrazing occurs through the β-(Ti, Mo) phase with grain boundaries and beryllides eutectic melting.

2023, Gurova, J., Bachurina, D., Kozlov, I., Efimov, V., Krutikova, O., Suchkov, A., Spitsyn, A., Gasparyan, Y., Гурова, Юлия Александровна, Козлов, Илья Владимирович, Ефимов, Виталий Сергеевич, Крутикова, Ольга Михайловна, Сучков, Алексей Николаевич, Гаспарян, Юрий Микаэлович

2022, БАЧУРИНА, Д. М., СУЧКОВ, А. Н., КОЗЛОВ, И. В., БОБЫРЬ, Н. П., ГУРОВА, Ю. А., ЕФИМОВ, В. С., КУЛИКОВА, Е. С., СПИЦИН, А. В., ГАСПАРЯН, Ю. М., Козлов, Илья Владимирович, Сучков, Алексей Николаевич, Гаспарян, Юрий Микаэлович

Существующие концептуальные проекты первой стенки и дивертора реактора ДЕМО подразумевают наличие неразъемного соединения вольфрама с малоактивируемой ферритно-мартенситной сталью [1,2]. Из-за разницы коэффициентов теплового расширения (КТР) W и стали их прямое соединение затруднено [3]. Перспективным методом получения такого соединения является высокотемпературная пайка быстрозакаленными ленточными сплавами припоями. Для компенсации различий КТР предлагается использование различных промежуточных слоев (V, Та и др.). К настоящему моменту предложено несколько компенсирующих проставок и припоев для соединения вольфрама со сталью. В подавляющем большинстве работ представлена пайка припоями на основе меди или никеля [4], которые, не удовлетворяют требованию малоактивируемости .

2023, Popov, N., Bachurina, D., Bogdanov, R., Kozlov, I., Dzhumaev, P., Sevryukov, O., Suchkov, A., Krutikova, O., Попов, Никита Сергеевич, Козлов, Илья Владимирович, Джумаев, Павел Сергеевич, Севрюков, Олег Николаевич, Сучков, Алексей Николаевич, Крутикова, Ольга Михайловна