East European Journal of Physics

5

Authors: A. V. Levenets, I. V. Kolodiy, N. V. Berezhnaya, Y. S. Lipovskaya

The structure and mechanical properties of high-entropy CoCrFeMnNi (equiatomic) and Co20Cr26Fe20Mn20Ni14 alloys, which differ significantly in the stacking-fault energy, are studied. The structure of the alloys was investigated in three states – as-cast, after homogenizing annealing at T = 1000 °C for 24h and after annealing at T = 850 °C. It was found that in the cast state and after homogenizing annealing at 1000 °C both alloys are single-phase solid solutions with a FCC lattice. Annealing at 850 °C preserves the single-phase state in the equiatomic CoCrFeMnNi alloy, but leads to the appearance of a σ-phase in the Co20Cr26Fe20Mn20Ni14 alloy. The mechanical properties of these alloys were studied in a single-phase state by uniaxial compression tests and hardness measurements. It was discovered, that both alloys in a single-phase state had high plasticity and tendency to force strain hardening. The behavior of hardening coefficients in the area of true strains e = 0.05 – 0.17 vary considerably. This may be due to a significant difference in the stacking-fault energy of the investigated alloys. As a result, in Co20Cr26Fe20Mn20Ni14 alloy along with dislocation deformation mechanism there is a high probability of implementation the twinning mechanism.

8

Authors: V. N. Bondarenko, A. V. Goncharov, V. I. Sukhostavets, T. Kh. Salikhov, A. A. Abdurahmonov

A technique for infrared thermometry remote monitoring of temperature of area of a polymer film under ion irradiation is described. Calculation part of the technique takes into account the case when the irradiated area is significantly smaller than the instrument field of view. Temperature measurements were carried out with 20 μm polyimide films irradiated by 1000 to 1600 keV protons, with 1…5 μA/cm2 current density. A model for calculation of temperature depth distribution in the irradiated film is developed. The model is also applicable for the case of ion irradiation in gaseous atmosphere, and takes into account temperature dependence of the polymer substance thermal conductivity, of the emissivity coefficient, and of the convective heat transfer coefficient. The calculated data are compared with the temperature measurements.

10

Authors: V. M. Kuklin, D. N. Litvinov, S. M. Sevidov, A. E. Sporov

In this paper, the self-consistent model was considered, consisting of a system of oscillators, the coupling between them was assumed to be integral (due to the fields formed as a result of their co-radiation). With the help of this model, the features of synchronization by waves of finite amplitude of a system of oscillators were refined, the initial phase values of which are random. The effect of nonlinearity, in particular, due to the change in the mass of the oscillator due to relativistic effects, was taken into account. It was shown that the nonlinearity does not violate the nature of the energy exchange between the wave and the oscillator system, leading only to a slight decrease in the efficiency of such an exchange.

24

Authors: M. I. Kopp, A. V. Tur, V. V. Yanovsky

We found a new large-scale instability, which arises in the rotating conductive fluid with small-scale turbulence. Turbulence is generated by small-scale external force with a low Reynolds number. The theory is built simply by the method of multiscale asymptotic expansions. Nonlinear equations for vortex and magnetic perturbations obtained in the third order for small Reynolds number. It is shown that the combined effects of the Coriolis force and the small external forces in a rotating conducting fluid possible large-scale instability. The large-scale increments of the instability, correspond to generation as the vortex and magnetic disturbances. This type of instability is classified as hydrodynamic and MHD alpha-effect. We studied the stationary regimes of nonlinear equations of magneto-vortex dynamo. In the limit of weakly conducting fluid found stationary solutions in the form of helical kinks. In the limit of high conductivity fluid was obtained stationary solutions in the form of nonlinear periodic waves and kinks.