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Information × Registration Number 0212U005169, 0107U000943 , R & D reports Title New peculiarities and mechanisms of anelastic deformation of solids under the condition of moderate and deep cooling. popup.stage_title Head Pal-Val Pavel Pavlovich, Registration Date 28-03-2012 Organization B.Verkin Institute for Low Temperature Physics and Engineering of National Academy of Science of Ukraine popup.description2 In the wide range of low and extremely low temperatures (0,5 - 340 K), new peculiarities of the plastic deformation, internal friction and fracture of nanostructured (NS) and ultrafine-grained (UFG) metals and alloys and metallic glasses are discovered. It is shown that plastic deformation of ultrafine-grained UFG and NS metals and alloys at low temperatures has, to a great extent, the dislocation nature but mechanisms of nucleation, slip and annihilation of dislocations have a number peculiarities. They are caused by significant number of boundaries that play role of sources, sinks and obstacles for dislocation motion. It is established that for all the UFG and NS materials the yield points increases essentially with grain size decrease (for nanocrystalline (NC) Ti up to 10 times). High strength parameters of materials studied is combined with high enough plasticity that make these materials perspective for technological use at cryogenic temperatures. Along with this, it was found that presence in the UFG metals of significant number of deformation lattice defects favours low-temperature jump-like plastic deformation (LTJPD), i.e. localization of the plastic deformation in UFG and NS materials is more pronounced than in their coarse-grained analogs. It is established that LTJPD develops in metals and alloys due to dynamic dislocation processes and is not caused only by the local overheating and thermomechanic instability. Cryomechanic techniques is suggested for obtaining pure bulk NC Ti with average grain size 30 nm. High mechanical characteristics of NC Ti along with excellent corrosion resistivity and biocompatibility make this material rather attractive for use as bone implant in medicine. When studying stability of the NS copper by the low-temperature acoustic spectroscopy method, it was shown that natural ageing and annealing at elevated temperatures lead to substantial changes of the defect structure parameters. The temperatures boundaries of a static recrystallization are determined. In the temperature range 2 - 20 K, experimental evidences of tunneling and thermoactivated relaxation of quasilocal excitations in disordered medium are obtained. A decrease of the excitation density due to natural ageing and high-temperature annealing is found. The results obtained might be used in textbooks for students and reference books for aerospace, cryogenic and nuclear engineering and industry. Product Description popup.authors Ісаєв М.В. Бенгус В.З. Брауде І.С. Лубенець С.В. Москаленко В.А. Пустовалов В.В. Табачникова О.Д. Фоменко Л.С. popup.nrat_date 2020-04-02 Close