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Information × Registration Number 0224U033447, (0124U000551) , R & D reports Title Statistical theory of micro- and nanostructural evolution in alloys and fuel cells under neutron irradiation popup.stage_title Моделювання динаміки випадіння преципітатів та сегрегації точкових дефектів у сплавах на основі заліза. Head Dvornichenko Alina V., Кандидат фізико-математичних наук Registration Date 27-12-2024 Organization Sumy State University popup.description1 The goal of this project is a self-consistent description of the processes of microstructural transformations in the structural materials of nuclear reactors and fuel cells under neutron irradiation by taking into account the radiation-induced processes of ballistic mixing and the dynamics of non-equilibrium point defects. In order to achieve the goal, the following tasks are planned to be solved in this project. Development of a generalized theoretical approach and phase-field model for studying the dynamics of precipitation/dissolution of precipitates of secondary phases and mechanisms of segregation/clustering of point defects in alloys based on iron and zirconium. Generalization of the phase field model of the evolution of gas-filled pores in uranium silicide. Establishing the conditions for precipitation of new phases enriched by chromium (for reactor covers) and niobium (for power-shell elements) during solid solution annealing and microstructural transformations during construction material irradiation. Modeling of precipitation processes of secondary phases during annealing of solid solutions. Modeling of the processes of dissolution of existing precipitates and radiation-stimulated precipitation of new precipitates for different values of the irradiation temperature, dose rate, and characteristics of ballistic mixing of atoms in irradiated materials. Modeling of growth processes of gas-filled pores in fuel cells under different irradiation conditions. Establishing the effect of irradiation conditions on the statistical properties of precipitates of new phases in irradiated materials and gas-filled pores in fuel cells. Analysis of the impact of irradiation on the physical and mechanical properties of structural materials and swelling of fuel cells popup.description2  A generalized phase field model has been developed to simulate the dynamics of microstructural transformations during solid solution heat treatment and irradiation in an iron-based Fe-Cr-Al alloy, taking into account thermodynamic potentials from the CALPHAD database and point defect dynamics. It has been established that an increase in the aluminum concentration in the alloy leads to an increase in the critical annealing temperature and induces phase segregation processes in the alloy. It has been found that an increase in the chromium and aluminum concentrations initiates phase segregation processes and leads to an increase in the linear size of precipitates and their volume fraction. It has been established that annealing at elevated temperatures leads to a decrease in the number of precipitates and an increase in their size. It has been found that an increase in the irradiation temperature supports phase segregation processes in alloys, when existing chromium precipitates in the unirradiated alloy remain stable. It is shown that an increase in the rate of defect generation leads to homogenization of the alloy microstructure due to the dissolution of existing precipitates and limitation of the irradiation temperature range for the implementation of phase separation processes. It is shown that during phase separation under the action of irradiation, the initially disordered system undergoes phase separation with the formation and growth of chromium precipitates up to 3.5 nm in size at doses of 3 a.d.a. with a decrease in their density. It is shown that the irradiation-supported phase separation processes lead to the formation of larger precipitates (up to 4.5 nm in size) compared to those initially formed during annealing Product Description popup.authors Borysiuk Vadym M. Dvornichenko Alina V. Lysenko Borys O. Liutyi Taras V. Nenia Anna V. Poluliakh Mari V. Rozghon Yuliia V. Kharlam Maksym І. Kharchenko Vasyl O. Kharchenko Dmytro O. Shvets Uliana S. popup.nrat_date 2024-12-27 Close