Персона: Никитин, Александр Александрович
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Александр Александрович
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- ПубликацияТолько метаданныеStudy of Microscopic Origins of Radiation Hardening of Eurofer 97 in Simulation Experiment with Ion Irradiation(2019) Khomich, A. A.; Iskandarov, N. A.; Khoroshilov, V. V.; Lukyanchuk, A. A.; Rogozhkin, S. V.; Nikitin, A. A.; Bogachev, A. A.; Рогожкин, Сергей Васильевич; Никитин, Александр Александрович; Богачев, Алексей Александрович© 2019, Pleiades Publishing, Ltd.Abstract: Low-temperature radiation hardening of prospective structural steel Eurofer 97 as the material for the first wall of the DEMO fusion reactor is studied in this work. Specimens of Eurofer 97 steel were irradiated with Fe ions up to 10 dpa at temperatures of 250, 300 and 400°C. Irradiated samples were studied by transmission electron microscopy and atom probe tomography. TEM study of irradiated samples showed preferential formation of dislocation loops at all temperatures of irradiation. Pair-correlation function analysis detected the initial stage of matrix solid solution decomposition of Eurofer 97 steel only at the temperature of 400°C. Detected microscopic changes and calculated hardening in the framework of the DBH (dispersed barrier hardening) model have shown that formation of dislocation loops is the main origin of low temperature radiation hardening of Eurofer 97 under irradiation with Fe ions with fluence up to 10 dpa.
- ПубликацияТолько метаданныеThe influence of Fe-ion irradiation on the microstructure of reduced activation ferritic-martensitic steel Eurofer 97(2019) Khomich, A. A.; Lukyanchuk, A. A.; Raznitsyn, O. A.; Shutov, A. S.; Rogozhkin, S. V.; Nikitin, A. A.; Рогожкин, Сергей Васильевич; Никитин, Александр АлександровичReduced activation ferritic/martensitic steels for in-vessel components of a fusion reactor have shown a decrease in plasticity and radiation hardening at low irradiation temperatures. The formation of dislocation loops and embryos of alpha' phase is considered the main reason for these effects. In this work, Eurofer 97 steel was irradiated with 5.6 MeV Fe2+ ions up to 10(20) m(-2) at 250, 300 and 400 degrees C. Transmission electron microscopy study of ion irradiated samples revealed nucleation of dislocation loops. The pair-correlation analysis of atom probe tomography data detected an initial stage of solid solution decomposition. The hardening of ion-irradiated Eurofer 97 was calculated with the dispersed barrier hardening model, taking into account radiation-induced dislocation loops to compare it with the change of yield stress in neutron-irradiated Eurofer 97. According to the obtained results, it can be supposed that the formation of dislocation loops plays the main role in the low-temperature radiation hardening of Eurofer 97 at a dose level up to similar to 10 dpa.
- ПубликацияТолько метаданныеA Study of the Effect of Ion Irradiation on the Mechanical Properties of Eurofer 97 Steel(2019) Gladkikh, E. V.; Kravchuk, K. S.; Useinov, A. S.; Nikitin, A. A.; Rogozhkin, S. V.; Никитин, Александр Александрович; Рогожкин, Сергей ВасильевичThe hardness values of samples of ferritic-martensitic steel Eurofer 97 in the initial state and after irradiation with 5.6 MeV Fe2+ ions up to a fluence of 1 x 10(16) cm(-2) at a temperature of 300 degrees C are compared. The mechanical properties are tested by the method of instrumental indentation using the dynamic mechanical analysis technique. To correct the obtained hardness values, the geometry of the plastic imprints is measured by the method of atomic force microscopy. Irradiation with heavy ions gives rise to an increase in the hardness value in comparison with the initial sample. This indicates a radiation-induced decrease in the plasticity of steel Eurofer 97, which should be taken into account in the case of using it as a construction material for new-generation fusion reactors.
- ПубликацияТолько метаданныеEmulation of Radiation Damage of Structural Materials for Fission and Fusion Power Plants Using Heavy Ion Beams(2019) Khomich, A. A.; Iskandarov, N. A.; Khoroshilov, V. V.; Lukyanchuk, A. A.; Rogozhkin, S. V.; Nikitin, A.; Bogachev, A. А.; Рогожкин, Сергей Васильевич; Никитин, Александр Александрович; Богачев, Алексей Александрович© 2019, Pleiades Publishing, Ltd.The study is devoted to the methodology of simulation experiments for the analysis of radiation damage of structural materials of nuclear power plants by irradiation with heavy ions and subsequent analysis with use of the ultramicroscopy and nanoindentation methods. Details of the irradiation experiments in the TIPr accelerator (Institute for Theoretical and Experimental Physics) with ion energy of 101 keV/nucleon are given. Current approaches to the analysis of radiation-induced changes in the structural phase state of samples irradiated with ions with use of transmission electron microscopy and atom probe tomography are demonstrated. Models for the evaluation of radiation hardening based on microscopic changes, as well as the capabilities of the nanoindentation method for direct measurement of the hardening of a specimen layer irradiated by ions, are considered.
- ПубликацияТолько метаданныеNanoindentation Study of the Effect of Low-Temperature Ion Irradiation on the Hardness of a Ferritic–Martensitic EK-181 Steel(2019) Kulevoi, T. V.; Fedin, P. A.; Iskandarov, N. A.; Kravchuk, K. S.; Nikitin, A. A.; Rogozhkin, S. V.; Никитин, Александр Александрович; Рогожкин, Сергей Васильевич© 2019, Pleiades Publishing, Ltd.Abstract: The hardness of a ferritic–martensitic steel EK-181 after ion irradiation to a maximum damaging dose of ~50 dpa in the temperature range 250–400°C is investigated. Nanoindentation is used to measure the mechanical properties. The hardnesses of the layer damaged by ions and that of the undamaged bulk material are found. At temperatures below 300°C, softening at a dose below 10 dpa and hardening at high doses of ~50 dpa are observed. Hardening is detected over the entire dose range at 400°C. The maximum hardness of the sample irradiated to ~50 dpa at 400°C is 1.7 GPa.
- ПубликацияТолько метаданныеSimulation of Ion Paths in the Target Material for the Injection Complex of the BELA Facility(2019) Ziiatdinova, A. V.; Fedin, P. A.; Nikitin, A. A.; Rogozhkin, S. V.; Kulevoy, T. V.; Федин, Петр Алексеевич; Никитин, Александр Александрович; Рогожкин, Сергей Васильевич; Кулевой, Тимур Вячеславович© 2019, Pleiades Publishing, Ltd.To realize the simulation experiments with the use of two ion beams at the injection complex of the BELA accelerator (Based on ECR ion source Linear Accelerator), it is necessary to determine the energy and irradiation angle of the beam of light ions which will be implanted into the region of radiation damage induced by heavy-ion beam. The depth of light-ion implantation is determined by the energy and kind of particles initiating the damage, as well as by their incidence angle. It is supposed that the incidence direction of heavy ions will coincide with the normal to the specimen surface. In our work, the necessary implantation zone for the iron ion beam with an energy of 3.2 MeV is located at depths of 300–800 nm. The simulation of the hydrogen and helium ion paths in the material of the iron target in the energy range from 150 to 600 keV at the angle to the normal from 0° to 65° is performed. The range of energies and irradiation angles for the hydrogen and helium ions are determined for the implantation into the radiation-induced defect-formation zone.
- ПубликацияТолько метаданныеQuantitative Analysis of Carbide Phases in Medium-Carbon Steel After Low-Temperature Tempering(2019) Ryabov, V. V.; Khlusova, E. I.; Zisman, A. A.; Luk'yanchuk, A. A.; Rogozhkin, S. V.; Nikitin, A. A.; Рогожкин, Сергей Васильевич; Никитин, Александр Александрович© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Structural features of high-strength wear-resistant steel formed after tempering at different temperatures are investigated. Temperature dependences are determined for steel hardness and impact strength. Temperature ranges are recorded for intermediate carbide formation, cementite particle formation, and residual austenite decomposition. The lath structure and carbide particle distribution are analyzed using transmission electron microscopy. Neutron diffraction is used to study the dependence of the proportion of retained austenite on temperature. Atom probe tomography is used to analyze micro-inhomogeneity in carbon and alloying element distribution.