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Information × Registration Number 0218U003183, 0115U001160 , R & D reports Title Investigation of regularities and mechanisms of low-temperature deformation of modern structurally modified materials popup.stage_title Head Pal-Val Pavlo Pavlovych, Registration Date 25-01-2018 Organization B.Verkin Institute for Low Temperature Physics and Engineering NAS of Ukraine popup.description2 The work is devoted to establishing physical mechanisms of plastic deformation, fracture, internal friction and microhardness of 2D crystals, nanostructured (NS), nanocrystalline (NC), ultrafine-grained (UFG) metals, high-entropy alloys (HEA) and polyimides under deep cooling conditions. When modeling the atomic structure of 2D crystalline nanoclusters, the existence and nonuniform distribution of atomic dilatations in clusters has been established. Analytical expressions for the interaction forces between pairs of point defects in a 2D crystal with arbitrary anisotropy are derived and their dependence on the topological charges of defects is established. The interaction of dislocations and crowdions with bending deformations of 2D crystals is investigated. It is shown that the action of transverse forces on the crystal determines the motion of dislocations and crowdions in a crystal plane. A high strength was revealed with a considerable reserve of ductility in the HEA in the range 4.2-350 K due to the creation of the NS state in them by the methods of severe plastic deformation (SPD). The three-stage process of the formation of the NC state of Ti is established. The grain refinement limit (~ 35 nm) was found for the formation of the NC state of HCP metals by the method of cryomechanical fragmentation. A morphological anisotropy of NC Ti crystallites has been detected, which determines the anisotropy of the yield point in the range 4.2-300 K. Anisotropy of the texture of the samples with respect to the rolling direction has been detected by the microindentation method. It has been established that the microhardness of HC Ti does not depend on deformation, which indicates the stability of its microstructure to mechanical loads. It is shown that the parameters of plastic flow instability of UFG copper are determined by grain size and dislocation density. It is established that after direct and equal-channel angular hydroextrusion, the samples of UFG copper differ in texture and in the fraction of large-angle boundaries. It is shown that the optimal combination of high strength and ductility is achieved in the Zr samples with low-energy boundaries. It was found that a significant increase in the dislocation density and a decrease in the average grain size during the Zr SPD fragmentation significantly affects the activation parameters of the thermally activated breakaway of dislocations. An appreciable thermal instability of the Zr samples is observed. Product Description popup.authors Іванченко Л.Г. Ісаєв М.В. Абраімов В.В. Алексенко Є.М. Безкорсий О.П. Брауде І.С. Ватажук О.М. Величко М.І. Волобуєв Ф.І. Гейдаров В.Г. Григорова Т.В. Забродін П.А. Заріцький І.П. Кіслов О.М. Казаров Ю.Г. Кириченко Г.І. Лебідь В.О. Лотоцька В.О. Лубенець С.В. Москаленко В.А. Нацик В.Д. Паль-Валь Л.М. Паль-Валь П.П. Погрібна Ю.М. Подольський О.В. Псарук І.А. Русакова Г.В. Сальтевський Г.І. Семеренко Ю.О. Смірнов А.Р. Смірнов С.М. Смолянець Р.В. Табачнікова О.Д. Федорко В.І. Фоменко В.С. Фоменко Л.С. Церковний О.І. Шаповалов Ю.О. Шляхов В.В. Шумілін С.Е. Яковенко Л.Ф. popup.nrat_date 2020-04-02 Close