[en] The phase transformation caused by high pressure torsion (HPT) of a cold rolled AISI 304L stainless steel was investigated. After cold rolling the steel has a microstructure of martensite α' (bcc) with a magnetization saturation of 136.0 A m^-2 kg^-1. The HPT processing with pressures of 2 and 5 GPa promoted the α' (bcc)→ε (hcp) partial transformation, as observed by X-ray diffraction. The magnetization saturation decreased by the increase of true deformation by HPT, which is in agreement to the α' decrease

[en] The deformation behavior under tension and pulse current in course-grained, nanostructured and amorphous titanium based alloys is investigated. The influence of grain size, structure state and current mode on shape memory effect and electroplastic effect has been shown. Structure refinement up to nanosize area, occurrence of interphase boundaries, and amorphous state in alloys suppress the electroplastic effect. In TiNi alloys with phase thermoelastic transformation induced by deformation or temperature, current pulses decreases stress jumps downwards induced by manifestation of the electroplastic effect and increases stress jumps upwards connected with the shape memory effect. (paper)

[en] The modification of polymer surfaces with fluorine–oxygen mixtures has been studied with wide variations in the process duration and percentage ratio between these gases in the mixture. The modification increases the hydrophilicity of the polymer surface, and, the higher the fraction of oxygen in the gas mixture and the longer the oxyfluorination time, the greater the increase in the hydrophilicity. The physicochemical properties of polymers, such as wettability, surface energy, and adhesion, may be regulated within rather wide ranges by varying oxyfluorination conditions. For example, in the case of polyolefins, the water contact angle changes from 78°‒87° for initial polymers to 49°‒60° for modified ones. For heterochain polymers, this range may be even wider and is for, e.g., poly(ethylene terephthalate) from 67° to 4°; i.e. almost complete water spreading over the polymer surface is achieved. The contribution of the polymer surface roughness to the observed values of the water contact angle has been determined before and after the chemical treatment. It has been shown that an increase in the wettability of the polymer surface as a result of oxyfluorination may be used to obtain polymer films capable of altering their wettability under subsequent tensile deformation.

[en] The influence of severe plastic torsion straining under pressure on the structure and magnetic properties of the alloy Pr20 Fe 73.5 N 5 Cu 1.5 at % is considered in the present work. Deformation results in the formation of an ultrafine-gained structure and subsequent annealing leads to an increase in coercivity to 1500 kA/m. (authors)

[en] The development of the digital transformation of the gas industry in the Russian Federation is mainly aimed at unique and giant fields. These fields provide the leading position of Russia in the world gas market and about 85 % of the total volume of gas production. The regulatory and technical base, the composition of the existing standards allows us to move to the practice of introducing digital gas technologies. The creation of a unified integrated model is being completed at the Bovanenkovo field. The creation of a digital twin of a unique gas field represents the transfer of a real field into virtual space through the use of Big data analytics and supercomputer technologies. (paper)

[en] Transport measurements at liquid helium temperatures were done on a number of Bi_2Te_2Se samples with thicknesses ranging from 30 to 200 μm in order to detect surface states. In each sample we observed Shubnikov–de Haas (SdH) oscillations and sublinear dependence of off-diagonal component of magnetoresistance tensor on magnetic field. The periods of SdH oscillations in inverse magnetic field were found to be the same within 15%. The positions of SdH oscillations are determined by the normal to surface component of magnetic field. We found that the measured conductivity can be well described by a model with two groups of electrons, 2D and 3D. The conductivity of 2D electrons was found to be relatively weakly varying from sample to sample and not depending on thickness in a systematic manner. This behavior can be explained only by their localization on the surface. Comparison of the results of magnetotransport measurements with our scanning tunneling spectroscopy results on atomically smooth Bi_2Te_2Se surface in ultrahigh vacuum led us to conclude that the surface electrons are separated from the bulk electrons by a depletion layer approximately 100 nm thick. This effect could provide the dominant contribution of surface electrons to conductivity in samples with thicknesses less than 200 nm

[en] The article considers problems and prospects of reducing the risks of occurrence of emergency situations of natural and technogenic character in the coastal river areas, as well as the usage for operational informing of the population of a comprehensive system that includes Federal, regional and local information centres. It is shown that the solution of the problem is based on the formation of information about emergency situations, their consequences, the state of radiation, chemical, medical, biological, explosive, fire and environmental safety in these areas, taking into account the coastal and transboundary situation to ensure their sustainable development. The authors defined the indicators and presented a strategy for collecting information and proposed a comprehensive system of support for management decisions aimed at preventing natural and man-made emergencies for the river coastal territory (RCT) of the Far East regions. (paper)

[en] Plasma driven permeation of hydrogen through 25 μm Nb foils was investigated under low-energy hydrogen ion irradiation in the range of membrane temperature 450-800 K and at different surface conditions. The interaction of hydrogen at molecular, atomic and ionizated states with niobium was under experimental research. The maximum value of low-temperature steady state permeation efficiency (SPE) was observed at Ar plasma cleaned inlet surface and with insignificant influence of outlet surface conditions. Such result is unusual and contradicts the developed classical representations and other published data for high-temperature range plasma-driven permeation. We explain this phenomenon by influence of defect structure of the polycrystalline membrane. The defects lead to the enhanced diffusion of hydrogen atoms along the crystallite sides. Such diffusion can essentially increase SPE of hydrogen through metal at low temperatures. The validity of this explanation was proved by the comparison of molecular hydrogen sorption and desorption measurements in poly- and mono-crystal Nb samples. The weighing method was used in that case. The phase transition β'→α in the Nb-H system is important for an explanation of SPE temperature dependencies in low-temperature range. The defects initiate phase transitions. The short-time enhanced hydrogen permeation was observed after irradiation of a membrane surface by Ar ions. The surface dissociation of the molecular ions, excited molecules and partially ordinary unexcited molecules of hydrogen can explain these observations

[en] This article examines the effect of ion implantation on the change in the mechanical characteristics of the Ti-Ni shape memory alloy. A comparison of the characteristics was carried out in the coarse-grained and nanostructured state on the initial alloy samples and on the samples after ion implantation. The implantation mode was chosen as the most optimal on the basis of previous studies. Irradiation mode parameters: dose - 2.3·10¹⁷ ion/cm², energy - 40 keV, ions -nickel, temperature - did not exceed 200 °C. The characteristics were studied by the nanoindentation method on a NanoHardnessTester, (CSM Instr.) At a load of 2 mN using a Berkovich-type diamond indenter. According to the data of nanoindentation by the Oliver-Pharr method, the value of hardness and Young’s modulus of elasticity were determined. Research results show that ion implantation leads to an increase in hardness. (paper)

[en] We report the effect of graphene (G) allotropic carbon modification in a content range of 0.5–2.0 wt % on the tribological, strength, and structural characteristics of an Al₂O₃/G nanocomposite produced by a 10-min plasma spark sintering (at a pressure of 50 MPa and a temperature of 1550°C) of a nanopowder mixture, previously subjected to ultrasonic dispersion in organic solvent. Its lubricant free friction and wear are tested at room temperature on a tribometer under a load of 20 N, at a roundabout motion of a ruby ball penetrator on a disk. The nanohardness and elastic modulus of the nanocomposite are determined via kinetic indentation. The fracture surface structure and friction track are monitored using a scanning electron microscope. The microstructure in the bulk of the nanocomposite was probed via dark- and bright-field transmission electron microscopy scanning of thin foils. The thermal stability of graphene was monitored via Raman spectroscopy. The introduction of graphene is shown to improve micro- and nanohardness, elasticity, and wear resistance by two to three orders of magnitude, as well as to slightly decrease the coefficient of friction. A graphene content of 2 wt % alters the mechanism of wear from brittle fracture to viscous shear owing to stronger coupling of matrix grains and the presence of agglomerates. A lack of degradation and the retention of graphene thermal stability are evidenced as well. The morphology of graphene particles reveals their preferential arrangement inside the corundum grains rather than at the grain boundaries.