The behavior of implanted deuterium in advanced lithium orthosilicate (Li4SiO4) pellets with addition of lithium metatitanate (Li2TiO3), and in reference Li4SiO4 pellets, has been investigated. Thermal desorption (TD) spectroscopy was used to study the deuterium interaction with radiation defects in materials. Computational evaluation of deuterium desorption within the framework of the diffusion-trapping model allowed to associate characteristics of experimental TD spectra with specific trapping sites in the material. It was found that deuterium desorption is limited mainly by intragranular diffusion of deuterium and its trapping by radiation defects associated with Li-vacancy traps. Deuterium gas release from both ceramics demonstrated similar trend indicating weak dependence of deuterium trapping behavior on phase composition. The change of the morphology and elemental composition of the pellets surface has been analyzed. SEM examination indicated that ion irradiation and subsequent thermal desorption annealing of two-phase ceramics leads to an increase in surface destruction processes.
The constantly growing consumption of electricity requires the development and implementation of more powerful and energy-intensive systems of the new generation. Fusion and fission reactors of the 4th generation (Gen-IV) will make it possible to cover the growing demand for electricity. Since Gen-IV reactors will operate at higher temperatures and radiation doses, the problem of selecting scientifically based structural materials arises, since conventional reactor materials are not suitable for use in such severe operating conditions. Among the structural materials under consideration for future generations of reactors, special attention is paid to 9…12% Cr ferritic-martensitic steels due to their higher radiation tolerance and excellent mechanical properties compared to traditionally used austenitic steels. This review presents the main ferritic-martensitic steels that will be used as structural materials, their structure, mechanical properties and various thermal and thermomechanical treatments applied to them.
The microstructure and radiation resistance of T91 martensitic steel were studied after thermomechanical treatment. The physical and technological foundations of the process of creating of a nanostructured state in T91 reactor steel have been developed. This structure was received by severe plastic deformation of T91 steel by the multiple “upsetting-extrusion” method (developed at the NSC KIPT) in two temperature ranges of deformation: in the region of austenite existing and with a successive decrease in the deformation temperature and an increase in cycles of “upsetting-extrusion” in the field of ferrite existence. For the further heat treatment the particular temperature range and deformation modes were chosen to obtain optimal structure. Also, the optimum temperature of tempering to receive the uniform structure was established. It was found that the average grain size of T91 steel decreases from 20 μm in the initial state to ~ 140 nm after 5 cycles of “upsetting-extrusion” in the ferrite interval and to ~ 100 nm after 3 cycles of deformation in the austenitic region. It was determined that with an increase in the number of cycles and a decrease in the deformation temperature, a rise in the degree of uniformity of grain size distribution occurs. In this case, the microhardness increases from 2090 MPa to 2850 MPa after 5 cycles of “upsetting-extrusion” in the ferritic interval. In the austenitic region, the microhardness values increase from 3400 to 3876 MPa. The swelling of T91 steel in two structural states, martensitic and ferritic, was determined. Thus, steel swelling at a high dose of irradiation with argon ions with an energy of 1.4 MeV (120 displacements per atom, irradiation temperature 460 ° C) is ΔV / V = 0.26% in the initial state (martensitic structure) and 0.65% for samples with a ferritic structure.
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