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Information × Registration Number 0223U004981, 0121U108687 , R & D reports Title A theory of phase transformations, kinetic and diffusion phenomena in condensed media popup.stage_title Head Bakai Oleksandr S., Registration Date 12-12-2023 Organization National Science Center "Kharkiv Institute of Physics and Technology" popup.description2 Fractional Brownian motion, a Gaussian non-Markov self-similar process with stationary long-correlated increments, has been found to induce anomalous diffusive behavior in a wide variety of physical systems. The correlation and diffusion properties of this random motion are fully characterized by its self-similarity index or Hurst exponent. However, recent experiments on the tracking of individual particles in biological cells have revealed very complex phenomena of anomalous diffusion, which cannot be attributed to the class of self-similar random processes. The process that preserves the properties of fractional Brownian motion at the level of one trajectory is studied; however, the Hurst index varies randomly from trajectory to trajectory. A general mathematical framework for the analytical, numerical, and statistical analysis of fractional Brownian motion with a random Hurst exponent is provided. Explicit formulas for the probability density function, rms increment, and increment autocovariance function are presented for three general Hurst exponent distributions, namely the two-point, uniform, and beta distributions. Molecular dynamics simulation of martensitic transformations in ordered alloys Ni5Al3 and Ni7Al5 depending on the dose of radiation damage was performed. The level of compositional disorder is related to the radiation dose by the substitution coefficient, i.e., the relative fraction of permutations of atoms at the crystal lattice sites. Compositional mixing together with the generation of Frenkel pairs are important characteristics of radiation damage in ordered alloys. It is shown that an increase in the level of disorder favors the high-temperature austenitic bcc phase. The temperature decrease of the martensitic transition reaches 300 °C. The research is focused on local compositional rearrangements observed during electron irradiation. It is expected that high-energy neutron irradiation may lead to an even greater effect. Product Description popup.authors Abyzov Olexander S Alekseiechkin Mykola Bakai Oleksandr Stepanovych Bezugly Oleksii I Borysenko Oleksandr O. Davydov Leonid M. Kotliar Volodymyr V. Lavrova Galyna M. Lazarev Mykola P. Mchedlov-Petrosian Petro O. Poluektov Yuri M. Soroka Oleksii O. Stepanovskii Yurii P. Turkin Anatoliy A. Chechkin Oleksiy V. popup.nrat_date 2023-12-12 Close