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Information × Registration Number 0215U006256, 0112U000725 , R & D reports Title Diffusive phase transformayions in open systems - kinetics and thermodynamics. popup.stage_title Head Gusak Andriy, Доктор фізико-математичних наук Registration Date 09-02-2015 Organization B. Khmelnitsky state university in Cherkasy popup.description2 Aim - development of the set of the analytical and computer models of the phase formation in open nano-sized systems with solid-phase reactions. . Object of study - nanoscale systems of the following types: contact zone of two metals at the start of the reactive diffusion, nanowires having a "point" contact with other nanowires or nanoparticles, composite systems such as core-shell multilayers with nanoscale period in which the Self-sustained High-temperature Synthesis (SHS) can propagate. Main results: 1. For the first time, the criterion is obtained and verified for suppression of harmful ?- Cu3Sn phase in reaction between copper and liquid tin. 2. The possibility of different spreading transitions for crystallization of solder on rough scallop-like surfaces of intermetallic Cu6Sn5 is discovered: depending on misorirntation between grains the two-dimensional spreading over the surface of scallops or the one-dimensional spreading along the junction of two scallop surfaces can be observed. 3. Using the method of phenomenological modeling and molecular dynamics, the first phase to form was predicted for the diffusive reaction between nickel and aluminum nanofilms. When pure nickel and pure aluminum are in contact and nucleation of crystalline intermetallics is kinetically suppressed, the first intermediate phase to form must be liquid solution. If deposition of films was carried at sufficiently high temperature of substrate, then the ordered intermediate phase appears in the contact zone, preventing the contact melting . 4. The analytical evaluation of temperature and speed for the front propagation along the nanoscale multilayer was made and tested in phenomenological models. The critical thickness of multilayer at which reaction is suppressed, is proportional to the efficiency of contact with ambient, demonstrates power dependence on the thermodynamic driving force and exponentially - on the activation energy of diffusion parameters. 5. Among various regimes of SHS reactions the following modes can be distiunguished: stationary, oscillating, pulsating modes and mode of quenching. 6. Generalization of Martin-Beke model was applied to simulate diffusion processes in binary alloys. Diffusion asymmetry makes a significant impact on the incubation period and the rate of growth phases. 7. The new model of the grain boundary solute drag was developed. 8. New analytical theory of decomposition and segregation in binary nanoparticles was developed - The criteria of collapse, the new size dependence of the decomposition cupola. 9. New model of the nucleation and growth of nickel silicide during point contact of nickel and silicon nanowires was developed and partially confirmed experimentally. Product Description popup.authors Запорожець Тетяна Василівна Ляшенко Олексій Юрійович Ляшенко Юрій Олексійович Пасічний Микола Олександрович Сторожук(Тютюнник) Надія Вікторівна popup.nrat_date 2020-04-02 Close