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Дан краткий обзор основных представлений и достижений динамической теории сверхзвукового роста мартенситных кристаллов. Показано, что рассмотрение предельного случая высокой скорости роста позволяет добиться физической прозрачности и математической простоты описания. Акцентируется внимание на ряде актуальных задач нового этапа исследований. Ключевые слова: мартенситные превращения, начальное возбужденное состояние, сверхзвуковая скорость. A brief review of basic concepts and main achievements of the dynamic theory of supersonic growth of martensitic crystals is given. It is shown that consideration of the limiting case of high growth speed allows to achieve a physical transparency and mathematical simplicity of the description. The attention is focused on a number of open problems of a new the stage of research.

Investigation of the thermoelastic martensitic transformation is of high interest nowadays because of the numerous applications of the materials with such structural peculiarities. Thermodynamics, kinetics, structure, morphology of martensitic transformation still remain unclear in many respects. From this point of view, the effective way to study various properties of metallic crystals on atomistic level is molecular dynamics simulation, for which good qualitative agreement with the experiment can be achieved even with simple Morse or Lennard-Jones interatomic potentials. In this paper, the effect of dislocations on the direct and reverse martensitic transformation is studied by molecular dynamics simulation in a two-dimensional model of the ordered alloy with the AB stoichiometry. The three dimensional analog to this structure is B2 superstructure based on bcc lattice, which is characteristic for intermetallic NiTi alloy. It is found, that the dislocations can be considered as the nucleation centers for martensite phase, increasing the temperature of the direct martensitic transformation in comparison with the homogeneous martensitic transformation. The martensite domains found in the structure after transformation and the reverse martensitic transformation takes place in the presence of the domain boundaries, meaning that the austenite nucleates heterogeneously. At the reverse transformation, splitting of perfect dislocations into partials dislocations took place. Thus, it was established in the present study that, on the one hand, dislocations affect the direct martensitic transformation as the nucleation centers, and from the other hand, reverse martensitic transformation changes the dislocation structure of the modeled alloy.

The canonic reaction of helium synthesis as a result of deuterium and tritium interaction can take place both in hightemperature and low-temperature variants. In both cases, the nuclei draw together so closely that Coulomb's barrier becomes enough transparent for tunneling. In the case of high-temperature synthesis the energy of chaotic thermal motion is needed to overcome the energy of electrostatic repulsion of «bare» nuclei. As a contrary, in the low-temperature variant, when deuterium and tritium nuclei replace protons in partially ionized hydrogen molecule, and negatively charged μ-meson replaces the only electron, electromagnetic interaction of nuclei with μ-meson provides nuclei approach each other to the critical distance of R с ≈ 5 • 10 -13 m. A hypothesis on appearance of intermedium quasi-molecular states (IQS) when negatively charged ions collide is formulated. It is supposed that in such states the nuclei can draw together due to effective attraction to the group of negatively charged electrons having higher mass and charge as compared with individual electron. The value R с ≈ 5 • 10 -13 m guarantees the tunneling only for light nuclei; therefore, the focus is made on ions' collision with α-clustered nuclei (having compositions divisible to α-particles compositions). It is expected that the new nuclei synthesis will take place in the presence of oncoming tunneling of relatively weakly connected α-particles from α-clustered nuclei. For IQS formation, the energy acquired by colliding ions in external fields has to be comparable with the energy of their entire ionization. It was shown that the energies (not exceeding 1 keV) of oxygen ions in experiments with electrolysis of water, were accompanied by appearance of mainly carbon, silicon and iron, which meet this condition. These facts testify for the existence of IQS that have to be considered as one of the necessary conditions of low-energy nuclear reactions. In the Conclusion the program of further research is briefly stated.