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Information × Registration Number 0221U102847, 0118U003109 , R & D reports Title Physical mechanisms of inelastic deformation of nanostructural crystalline materials, high-entropy alloys and polymer compositions under conditions of moderate and deep cooling. popup.stage_title Head Pal-Val Pavel P., Доктор фізико-математичних наук Registration Date 10-02-2021 Organization B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine popup.description2 It was found that in the nanostructured alloy AZ31, subjected to equal-channel angular pression (ECAP), plastic deformation develops abruptly. It is established that this is a consequence of avalanche-like dynamics of dislocations in conditions of low temperatures and high flow voltages. The scale of the avalanche (amplitude of voltage spikes) depends on the density of dislocations, which increases significantly due to the ECAP. As the density of dislocations decreases, the amplitude of the jumps decreases, but their variance increases. For a new class of high-strength Ti30Zr25Hf15Nb20Ta10 and CoCrFeNiMn weights with BCC and fcc lattices, an improvement in the ratio of strength and ductility at low temperatures was found. It is established that in the range of 4.2-350 K the microscopic mechanisms of plastic deformation in wind farms and traditional alloys are identical. These results can be used to predict the behavior of new materials in extreme conditions of their operation in the design of cryogenic and space technology. A study of the acoustic properties of Cu-Fe nanostructured fibrous composites with different iron fiber contents at T <100 K in the temperature range of 5-310 K revealed acoustic relaxation peaks due to thermoactivated motion of dislocations in the primary and secondary reliefs of Peierls. In experiments on microindentation of polystyrene (linear amorphous thermoplastic) in liquid nitrogen, signs of formation of fibrillar-porous nanostructures (crazes) with a much lower glass transition temperature than in the block material and significantly different parameters of forced mold under the indenter of the local zone were revealed. The theory of tunneling-jump diffusion of point defects in quantum crystals is compared with the results of experimental studies of the vacancy creep of 3He and 4He crystals. Empirical estimates for the energy and tunnel parameters of vacancies as localized quantum excitations in these crystals are obtained.   Product Description popup.authors popup.nrat_date 2021-02-10 Close