Том 8, № 3 (2017)

In the framework of the model of radiation-enhanced diffusion in the systems with impurities, effects of the formation of “vacancy–impurity atom” complexes on accumulation and annealing of radiation defects, rate of the growth of vacancy voids, and radiation creep in Fe-based austenite alloys are investigated. The temperature dependences of the steady-state concentration of radiation point defects, the concentration of vacancy complexes, and the effective coefficient of mutual recombination of radiation defects in materials with impurity complexes with a different bonding energy are calculated. The possibility of the suppression of the vacancy swelling and radiation creep effects due to formation of “vacancy–impurity atom” complexes having a high bonding energy is shown.

The method of modification of the outer surface of the cladding of fuel elements from E110 Zr alloy by means of irradiation with a radial beam of Ar⁺ ions with a broad energy spectrum is proposed. It is shown that the use of ion beam treatment at the final stage of the cladding production can improve the surface quality owing to removal of a large part of surface defects after mechanical polishing. The kinetics of the growth of oxide films on ion-beam-treated (cleaning or polishing by Ar⁺ ions) tubular Zr alloy specimens in a steam environment (350, 375, and 400°C up to 3000 h) was investigated. Monoclinic zirconia layer formation is found to occur on the specimen surface oxidized at 350°C in water and steam environments. Oxidation of the fragments of the alloy fuel-element cladding in steam under pressure contributes to the formation of a thicker and more friable oxide film in comparison with the oxidation in water.

The X-ray diffraction method is used to study radiation-induced changes in the structure and phase state of a model Fe–5% Mo alloy after electron irradiation at room temperature and 400°C. The observed radiation-induced softening of the alloy is explained by a decrease in the Mo concentration in solid solution and an increase in the number of lattice defects. This conclusion is confirmed by the shift of the 200 diffraction maximum toward larger angles and its broadening. Irradiation leads to the oxidation of the alloy, and additional annealing at 400°C causes the formation of spinel Fe₂MoO₄ and alloy strengthening.

The texture formed in the surface layer of a recrystallized VT6 titanium alloy irradiated by highcurrent pulsed electron beams (HEBs) in a melting mode is studied. It was ascertained that irradiation in the melting mode leads to the formation of compression texture and fine globular-lamellar structure in the surface layer with thickness of 20 μm with preferred orientation of α, α′, and α″ lamellae parallel or nearly parallel to the surface. Structural changes observed in the surface layer are the cause of improvement of fatigue strength of titanium alloy induced by HEB treatment.

The effects of mechanical, electrochemical, laser, and electrolytic plasma treatment on the morphology and grade of finish of the outside and face surfaces of stator rings made of electrical steel are investigated with the use of X-ray diffraction analysis.

By metallography and optical interferometry methods, the structure of 09G2S steel cutting seams fabricated with the use of narrow jet plasma technology is analyzed. The high quality of the seams allows welding without the removal of the heat-affected zones. The application of the new narrow jet plasma cutting technology provides high-quality welding seams, high efficiency of the process, and low energy consumption.

The effect of a high-power pulsed flow of deuterium ions and deuterium plasma generated in a plasma focus setup on the surface structure of a Ti plate was investigated. It was established that, depending on the radiation-thermal conditions on the surface, three zones with different surface morphology, structure, and defects were formed in the surface layer irradiated. The peculiarities of the surface damage in the center of the irradiated region of the Ti target exposed to the most severe radiation (power density of the ion and plasma flows of q_i ≈ 10¹¹–10¹² and q_p ≈ 10⁹–10¹⁰ W/cm², respectively) were studied, as well as those for the peripheral region exposed to softer radiation.

The elemental and phase composition of the surface layer of Hardox 450 steel with a composite TiB₂–Mo coating sprayed by an electro-explosive method are investigated after pulsed irradiation with an intense electron beam of submillisecond duration. Electron-beam treatment conditions leading to formation of a dense surface layer with high luster with a submicrograin structure on the basis of titanium diboride and nickel are ascertained. It is shown that an electron-beam treatment under melting rate leads to formation of a surface layer with homogeneous structure and uniform concentration distribution.

By X-ray diffraction and transmission diffraction electron microscopy methods, the phase composition, macro- and microstresses, and microstructure in a Ti_1–xAl_xN coating and a substrate were investigated. The coatings were deposited by magnetron sputtering of a Ti–Al target in an Ar + N gas reaction mixture on a substrate of austenitic steel 12Kh18N10T preliminarily bombarded with a titanium ion beam. It was found that the increase in the duration of the preliminary ion treatment of the substrate leads to increasing compression macrostresses and refining of a nanocrystalline columnar microstructure in the Ti_1–xAl_xN coating.

The method of production of group IV powders for additive manufacturing is presented. Powders are produced in the hydrogenation-dehydrogenation process followed by plasma spheroidization of prepared polygonal powders. The dependence of composition of hydrides on amount of absorbed hydrogen is established for the group IV metals; it allows optimizing the technological parameters of processes for hydrogenation and grinding. It is shown that spherical powders of titanium, Ti–6Al–4V, and Zr–10% Ti of mass fractions of 40–70 μm and not less than 40 μm with calculated spheroidization level achieving 96% may be produced in Ar + 8 vol % H₂ thermal plasma flow generated by an arc-jet plasma generator. The average roundness factor is 1.01.

Magnetically hard Fe–Cr–Co alloys doped with molybdenum and tungsten are prepared using powder metallurgy technology. It is found that chromium evaporation from the specimen surface occurs during sintering, which results in mass losses and nonuniform chemical composition and has a negative impact on the functional properties of the sintered material. A mathematical model describing the diffusional mass transfer and evaporation of chromium in a sample being sintered is presented. The modeled chromium concentration profiles are in qualitative agreement with the corresponding experimental profiles of the sintered specimens obtained via energy-dispersive X-ray analysis, performed using an electron microprobe. The evaporation of chromium is found to be the most intense in the first few minutes of sintering.

This article discusses the patterns of deagglomeration of aluminum oxyhydroxide nanosheets upon electrohydraulic discharge. The dispersion efficiency by electrohydraulic discharge is higher than that of ultrasound impact. The highest influence on destruction efficiency is exerted by the time of energy release, which determines the intensity of cavitation processes in water. No disintegration of initial nanostructures is observed under the selected parameters of electric pulses.

The thermal analysis technique of estimating the ability of a melt to overcool is used to determine the optimum technological regimes of melt preparation in all the production stages of amorphous wires. The temperature range of high-temperature melt homogenization and the regimes of precursor extraction and melting are defined for the model Co₆₉Fe₄Cr₄Si₁₂B₁₁ alloy. With use of the established regimes of heat treatment, the precursor melting is conducted and the samples of high-ductile amorphous microwires with a diameter 200 μm are produced by the Ulitovsky–Taylor method.