Vol 59, No 2 (2016)

The influence of thermal annealing within the temperature range 100–300°C on the structural-phase state of a Ni–Ti alloy with shape memory effect (SME) implanted with ₈₄Kr ions at the energies E = 280 keV and 1.75 MeV/nucl and the fluences within 5·10¹²–1·10²⁰ ion/m² is investigated. For the samples modified by ⁸⁴Kr ions at E = 1.75 MeV/nucl up to the fluences 1·10²⁰ and 5·10¹² ion/m², the formation of a martensitic NiTi phase with the B19^′ structure, responsible for the SME, is revealed at the annealing temperatures 100 and 300°C, respectively, in the near-surface region corresponding to the outrange area. This is accompanied by the formation of nanosized NiTi particles in the R-phase. As the implantation fluence increases, the probability of their formation decreases. It is shown that annealing of the implanted structures can increase the strength of the Ni–Ti alloy. The degree of hardening is determined by the value of annealing temperature, and an increase in strength is primarily due to ordering of the radiation-induced defect structures (phases). A correlation between the onset temperature of a forward martensitic transition and the structural-phase state of the thermally annealed Ni–Ti alloy is established.

A fluctuation hot-spot photoinitiation model is proposed for primary explosives. The model describes the explosion probability as a function of the initiation time. For the experimental verification of the model, an investigation of the dependence of an explosion on the initiation time, including the registration of the glow signal, is performed. It is found that the dependence of the characteristic time of the glow signal rise on the initiation time is of non-monotonic character. An evaluation of the model parameters is made.

Based on molecular-kinetic representations, theory of hydrogen absorption-desorption processes in binary Mg–Fe and Mg–Ni alloys is developed. Free energies of hydrides of these alloys are calculated. Equations of their thermodynamically equilibrium state determining the P–T–c diagrams are derived. A temperature dependence of the desorbed hydrogen concentration is established. A maximal desorption temperature is estimated. The state diagrams determining the concentration dependence of the maximal desorption temperature are constructed. Isopleths and isotherms of hydrogen solubility in the alloys are calculated. The possibility of manifestation of the hysteresis effect in hydrogen solubility isotherms is revealed and the decrease of the width and length of a hysteresis loop with increasing temperature is demonstrated together with the influence of the magnesium hydrate MgH₂ in Mg₂FeH₆ samples and running of chemical reactions on the behavior of the isotherms and the occurrence of bends and jumps in them. All established functional dependences of the sorption properties of the examined alloys are compared with experimental data available from the literature.

A solution of the Couette problem for a Fermi gas is constructed. The kinetic Bhatnagar–Gross–Krook (BGK) equation is used. Almost specular boundary conditions are considered. Formulas for the mass flux and the heat flux of the gas are obtained. These fluxes are proportional to the difference of the tangential momentum accommodation coefficients of the molecules. An expression for the viscous drag force acting on the walls of the channel is also found. An analysis of the macroparameters of the gas is performed. The limit to classical gases is taken. The obtained results are found to go over to the known results in this limit.

An Abelian group of three-dimensional Havrda–Charvat–Daroczy entropy vectors that depend on three distributions is defined, and the composition law of vectors with quadratic nonlinearity is determined. A geometric representation of the group in global four-dimensional Finsler space is considered. Properties of nonextensive entropy vectors that depend on three distributions are derived. An additive angular measure and a three-dimensional angular vector parameter are defined.

Polarization methods of measuring the roll angle of an object in motion with the help of radio beacon systems are considered. The polarization properties of the beacon signals received on board the object and amplitude-phase processing of their orthogonal polarized components are used to accomplish this goal.

Peculiarities of determining the concentration and distribution profile of dopant in the near-surface layer of a semiconductor by measuring the admittance of MIS structures based on p-Hg0.78Cd0.22Te grown by molecular beam epitaxy are studied. A technique is proposed for the determining the concentration of dopant based on the measurement of the admittance of MIS structures in the frequency range of 50 kHz – 1 MHz. It is shown that in this frequency range, the capacitance-voltage characteristics of MIS structures based on p-Hg_0.78Cd_0.22Te with a near-surface graded-gap layer have a high- frequency behavior with respect to the recharge time of surface states located near the Fermi level of intrinsic semiconductor. The distribution profile of dopant in the nearsurface layer of the semiconductor is calculated. It is shown that in p-Hg_0.78Cd_0.22Te with a near-surface graded-gap layer, the dopant concentration has the lowest value near the interface with the insulator.

Based on the Monte Carlo method, a model of growth of thin films prepared by oblique angle deposition of particles is constructed. The morphology of structures synthesized by simulation is analyzed. To study the character of distribution of microstructural elements (columns) in the film plane, the autocorrelation function of the microstructure and the fast Fourier transform are used. It is shown that with increasing angle of particle incidence, the film density monotonically decreases; in this case, anisotropy arises and monotonically increases in the cross sections of columns, and the anisotropy of distribution of columns in the substrate plane also increases.

An improved version of the equation of state model for two-component fluid mixtures whose molecules interact with the Exp-6 type potential has been proposed in previous works. The thermodynamic parameters of N₂, O₂, and CO₂ shock-wave compression are calculated using the equation of state model for two-component fluid mixtures based on perturbation theory. Products of compression of these substances are two-component mixtures. Analogous calculations are also performed using an effective one-fluid model. A comparison of the results obtained with the available experimental data and results of Monte Carlo simulation allows us to conclude that the proposed theoretical equation of state model is superior to effective one-fluid model in accuracy and reliably describes the thermodynamic properties of two-component fluid mixtures in a wide pressure and temperature ranges.

A (2+1)-dimensional gauge model is investigated. The presence of additional local U(1) symmetry, not associated with a physical gauge field, leads to the existence in the given model of two-dimensional non-vortex topological solitons carrying unquantized magnetic flux. Topological solitons of the given type were found numerically for fixed values of the model parameters. Analytical calculations of some properties of non-vortex topological solitons were performed. Universal dependences of the energy and magnetic flux of a non-vortex topological soliton on a dimensionless combination of parameters of the gauge model were obtained numerically. A comparative analysis of the properties of a non-vortex topological soliton and an Abrikosov–Nielsen–Olesen classical vortex is provided.

Dependences of the transmittance, absorbance, and reflectance of the composite based on a transparent matrix and copper spherical nanoparticles on the sample thickness and the mass fraction of particles are calculated for radiation of the first and second harmonics of a neodymium laser using the Mie theory and the stationary radiation transfer equation. Distributions of the luminance gain are calculated at different distances from the sample surface. It is shown that the luminance gain increases with nanoparticle radius and radiation wavelength due to multiple scattering. In the limit of a small sample thickness, the luminance gain has a threshold value due to the effect of the total internal reflection. Results obtained are needed for optimization of an optical detonator capsule based on a transparent explosive material and copper nanoparticles.

A method is proposed for determining the crystallographic directions in crystals of various point symmetry, along which the combination of physical properties of various ranks and Curie symmetry gets a predetermined value. The method is demonstrated for the combination of the second-rank tensors describing optical and thermal properties of crystals of the monoclinic system. The possibility of using the proposed method for the physical properties of high ranks is demonstrated.

Results of investigations of electromechanical systems with high-coercive permanent magnets from the standpoint of finding an optimal solution to reach the best energy characteristics and to ensure reliability of magnetic system design are presented.