The paper presents research results of the evolution of dislocation structures in low-stability Cu–Mn alloys deformed at different temperatures. The dislocation structure evolution in these alloys indicates to an important process during a transfer from one deformation stage to another. Each stage is characterized by its own strain carrier in the form of the specific dislocation structure with the highest volume fraction at the given stage. The strain carrier from the preceded stage gradually dissapears at the given stage with increasing deformation, and the strain carrier from the successive stage appears. Thus, in a certain strain range, there are strain carriers from the preceded stage, given stage, and successive stage. It is supposed that the formation of the cellular structure corresponds to the kinetic diffuse first-order phase transition to the dislocation structure.

The paper focuses on the evolution of the dislocation structure in Cu-Аl and Cu-Мn polycrystalline alloys in the low-stability state. Experiments conducted at different temperatures, show that the main structure of alloys having different content of Al and Mn alloying elements, changes insignificantly with increasing temperature in contrast to the density of dislocation barriers, dislocation clusters, dissociated dislocations, and stacking faults. Dislocation parameters of Cu-Mn alloys decrease with increasing temperature, while Cu-Al alloys manifest another behavior. The temperature effect on the dislocation structure parameters is different in Cu-Аl and Cu-Мn alloys. With increasing strain temperature, the average dislocation density in Cu-Mn alloys decreases, and grows in Cu-Al alloys. Misorientations in the structure, density of extinction contours and subboudaries reduce in Cu-Mn alloys and grow in Cu-Al alloys. It is found that the behavior of the dislocation structure parameters depends on temperature and is different in Cu-Аl and Cu-Мn alloys.

Results of investigations of the structural state of the AlNiNbTiCo high-entropy alloy (HEA) obtained by mechanical synthesis of pure Al, Ti, Ni, Co, and Nb metals for 30, 40, and 50 min are presented. It is shown that the AlNiNbTiCo HEA belongs to stable structures near the melting temperature. By the method of inverse convex hulls (InveseHubWeb), the temperature interval of structure stability equal to ∆T = 1578–2935 K has been found, and the lattice is created by predicting the structures in the USPEX code. The amorphous AlNiNbTiCo HEA structural state is determined by the simple AlNiNbTiCo-3 cubic lattice. It is shown that the AlNiNbTiCo-3 lattice dominates in the AlNiNbTiCo HEA synthesized for 30, 40, and 50 min.

Rebar coupling connections are widely used for joints, and it is necessary to get information about the stress field distribution on the coupling surface at uniaxial tension to characterize operation of such joints. Purpose: The aim of the work is to study the stress-strain state of rebar connections under tension, full-scale junctions of the type A500 rods, and the deformation influence on the steel microstructure of grade С1020. Methodology: Non-contact three-dimensional imaging system VIC-3D and digital image correlation and tracking for studying stress-strain state of rebar connection; transmission electron microscopy for studying the steel microstructure. Research findings: Load-displacement curves are suggested for the valve coupling, and three deformation stages are identified: 1) elastic deformation of the coupling connection, 2) parabolic hardening, 3) preceding the coupling connection destruction. The analysis of the strain field distribution on the coupling connection shows that at any time, plastic strain localizes in certain zones of the sample. The stress field evolution on the coupling connection correlates with the indicated deformation stages. The compliance of the rebar joint made of seamless hot-deformed tube with an outer and inner diameters 51 and 32 mm, respectively, made of С1020 steel grade, induces 500 MPa stress in the normal section of rebar under the tensile axial load. Value: It is shown that during uniaxial tension of 0 to 5 %, perlite fractures, which is accompanied by further polarization of the dislocation structure. The internal stress amplitude increases and at 5% tension, far-range stresses grow as compared with those induced forest dislocations. The main contribution to far-range stresses and their change at 5 % tension is made by the elastic component, that promotes to the microcrack formation.

Using the methods of advanced material physics, the structural-phase state of a layer of high-entropy high-speed non-equiatomic molybdenum tool steel formed by electric arc surfacing in a nitrogen atmosphere is studied. The thermodynamical and mechanical (elastic moduli) properties of the surfaced layer are examined in a temperature interval of 300–1400°C, and a phase-composition diagram is presented. It is observed that a temperature increase is accompanied by an α→γ polymorphic transformation, followed by a decrease in the content of carbide phases and elastic moduli.

Using the method of transmission electron microscopy (TEM) of thin foils, the nucleation and propagation of microcracks in various structures of the plastic zone in the polycrystalline low-stability copper–aluminum alloys are studied in the vicinity of their structural-phase transformation into a crack-bearing state. The evolution of misoriented dislocation substructures (DSSs), formed in the low-stability pre-transitional states in the vicinity of the cracking stability loss in the stage of developed plastic strain, is discussed. The relationship between the fine structure surrounding the microcracks and the dislocation substructure formed by the time of the material failure, i.e., the low-stability state of the material in the vicinity of its structural-phase transition into a into a crack-bearing state, is revealed. The principal factors, characterizing the dislocation density in these states of the material and the dislocation density in the substructures where microcracks nucleate, are identified. These factors are the misorientation boundaries of different origins and the long-range stress fields. The changes of the structure and the long-range stress fields are examined as a function of the distance from the microcracks and their tips.

The authors have presented results of uniaxial-tension testing of specimens of the layered composite "silumin/carbon-fiber-reinforced-plastic" (AK5M2/CFRP). AK5M2-grade silumin of hypoeutectic composition with the irradiation of the specimen′s surface by a pulsed laser beam was taken as the basic material. To create layered composites, carbon unidirectional fabric "CARBONWRAP Tape 230" produced at the Joint Stock Company Nanotechnological Center of Composites (NCC) was glued to the silumin surface. The binary epoxy compound "CARBONWRAP Resin 530+" produced at NCC was used as the binder. The uniaxial tension test of the specimens was implemented on an INSTRON 3382 testing machine at an extension rate of 0.3 mm/min. The evolution of deformation fields on the specimen′s surface was obtained using a VIC-3D digital optical system based on the method of correlation of digital stereoscopic images. From the testing results, the diagrams of deformation under uniaxial tension of the AK5M2/CFRP were constructed. The electron-microscopic image of the silumin surface layer was obtained by the scanning-electron-microscopy methods. An analysis of the structure of its influence on the physicomechanical properties was performed. An analysis of the strained state of the specimens was made by the patterns of distributions of longitudinal and transverse deformations in space and time.

High-entropy alloys based on refractory metals, possessing an unusual combination of physical, mechanical, tribological, electrophysical, etc. properties, can be recommended for use in various fields of industry and medicine. The aim of the work is to study the growth process of high- entropy alloys films of the Ti-Nb-Zr-Ta-Hf-Cu system in real time by X-ray phase analysis using synchrotron radiation. Experiments on the deposition of multielement metal films were carried out the VEIPS-1 setup developed at the Institute of high current electronics Siberian branch of the Russian academy of sciences for studying the processes of the film and coating formation on a synchrotron radiation source. The process of in situ thin film structure formation with high time resolution was studied using a synchrotron radiation source - the VEPP-3 electron storage ring, the Institute nuclear physics, Siberian branch of the Russian academy of sciences. It is shown that the deposition Ti-Nb-Zr-Ta-Hf-Cu plasma on a HG40 substrate is accompanied by the formation of an amorphous crystalline state represented by phases of the composition (presumably) Ti-Nb-Zr-Ta-Hf-Cu, TiZr, NbZr, and CuTiZr, formed at different stages of film deposition. The main phase is the Ti-Nb-Zr-TaHf-Cu composition.

The influence of alloying on the local structural features of the experimental samples is studied in the regions of their potential cracking in the low-stability states with an aim of revealing the regularities of cracking and fracture. It is found out that the microcrack density in the neighborhood of the fracture region in the Cu+5at.

The structural-phase sates and defect substructure are studied by the method of transmission electron microscopy using diffraction at different distances from the wheel–rail contact surface along the central axis of symmetry of the top of rail (TOR) (rolling surface) and along the radius of rounding (fluting) of the differentially hardened rails of the DH400RK category made of hypereutectoid steel after their continuous service. Using the obtained structure parameters, the estimates are made of the hardening mechanisms (strengthening by pearlite component, incoherent cementite particles, grain- and subgrain boundaries, dislocation substructure and internal stress fields) controlling the yield stress in the steel under study. A comparison is performed of the quantitative fine structure parameters and the contributions into hardening on the rolling surface and fluting. It is found out that the prevailing morphological component near the wheel– rail contact surface is the subgrain structure, and in the fluting – strengthening by incoherent particles.

In this study, the processes of thermal decomposition of wood during its treatment with a plasma flow are considered. To develop a mathematical model of these processes, a differential thermogravimetric analysis of the heating of larch samples in an argon atmosphere at a rate of 10-20 degrees/min is carried out. Based on the results obtained, a mathematical model of thermal decomposition is proposed, including four stages. The wood during heating is represented by a mixture of six components. At each stage, the kinetic parameters of the reactions are determined by processing measurements at a heating rate of 20 degrees/min. The equations of chemical kinetics describing changes in the mass of wood components are numerically solved using the finite-difference implicit Euler method and the obtained reaction parameters. The numerical solution to the equations of chemical kinetics with these parameters shows satisfactory agreement with the data from the corresponding experiment. The calculation performed at a heating rate of 10 degrees/min with the same kinetic parameters also shows satisfactory agreement with the measurements. Thus, the obtained reaction parameters do not depend on the heating rate in the considered range. The proposed model can be used in the mathematical description of changes in the structure and thermal state of wood samples exposed to high-temperature plasma flow treatment.

The paper presents results of correlation analysis of longitudinal strain values at different times during uniaxial tensile loading of flat specimens of technically pure A7-grade aluminum. The factor analysis allows distinguishing several factors responsible for the coordinated change of surface deformations at different deformation stages. Three characteristic zones are identified for the correlation matrix and diagrams of factor loads, which are correlated with the stages on the deformation curve. The factors are described in accordance with the stages of the deformation process, and their interpretation is proposed through the initial variables: the distribution of deformation values over the sample surface and time.

Using the method of transmission electron microscopy (TEM) of thin foils, nucleation and propagation of microckracks are studied in different plastic zone structures. An interrelation between the fine structure around the microcracks and the types and parameters of the dislocation substructure formed by the point of fracture of the material, i.e. its low-stability state in the vicinity of a structural transformation into a state with cracks is found out. The main factors characterizing the dislocation density in the substructures are identified. These factors are the misorientation boundaries of various origins and long-range stress fields. The changes of the plastic zone structure and its parameters are examined from the mactrocrack and its tip inwards the material.

The paper presents research results of the β-SiAlON production from aluminum, silicon and urea nitrides using high-enthalpy thermal plasma flow. Physicochemical properties of β-SiAlON are studied by using the X-ray phase analysis, scanning electron microscopy, and differential thermal analysis. It is shown that at the spicified plasma jet parameters, a thermochemical reaction occurs with the formation of β-Si 5 AlON 7 . Three zones of the structure formation caused by the temperature gradient in the bulk material as a result of the plasma exposure, are identified and studied. The first zone is directly irradiated by the plasma. The second is the transition zone, which locates between the first and third zones. The third is the thermal heating zone provided by the heat transfer from the irradiated zone.

A study was made of the effect of low-temperature plasma and pulsed electron beam irradiation on a mixture of silicon and aluminum nitride powders. It was found that as a result of irradiation with high-enthalpy plasma flux on the studied sample a thermochemical reaction occurred with the formation of a multiphase mixture in which the main product is β-SiAlON. Irradiation with a pulsed electron-pulse beam led to the formation of compounds based on β-SiAlON with different chemical compositions. The morphology of particles on the surface of irradiated samples was determined. The parameters of the crystal structure of compounds based on SiAlON is calculated.

Получены зависимости напряжения течения от деформации при разных температурах однородных твердых растворов на основе сплавов Cu–Mn с ГЦК кристаллической решеткой в зависимости от состава. Установлено, что различие между кривыми напряжения течения при разных температурах, растет с увеличением содержания Mn в сплаве. Представлены результаты исследования эволюции дислокационной структуры в сплавах Cu–Mn с содержанием марганца 1, 2, 4 и 6 ат. % в интервале размеров зерен 20…240 мкм при температурах деформации от 293 до 673 К методами дифракционной электронной микроскопии. Установлены зависимости скалярной плотности дислокаций от размера зерен и температуры испытания в сплавах Cu–Mn. Установлено, что с увеличением степени деформации происходит значительный рост средней скалярной плотности дислокаций. При фиксированной степени деформации во всех исследованных сплавах увеличение температуры деформации приводит к уменьшению плотности дислокации. В интервале размеров зерен от 10 до 100 мкм при всех температурах испытания наблюдается интенсивное уменьшение средней скалярной плотности дислокаций. Для размеров зерен свыше 100 мкм данная величина плотности дислокаций не изменяется. По микроснимкам, полученных в электронном микроскопе по ширине изгибных экстинкционных деформационных контуров измерялись численные значения кривизны-кручения кристаллической решетки. Установлено, что величина кривизны-кручения кристаллической решетке возрастает с деформацией нелинейным образом во всех исследованных сплавах. Величина кривизны-кручения кристаллической решетке при фиксированной степени деформации сплавах с размером зерна ~ 10 мкм больше, чем в сплавах с более высокими размерами зерен ~200 мкм.

The paper presents research results of the β-SiAlON production from aluminum, silicon and urea nitrides using high-enthalpy thermal plasma flow. Physicochemical properties of β-SiAlON are studied by using the X-ray phase analysis, scanning electron microscopy, and differential thermal analysis. It is shown that at the spicified plasma jet parameters, a thermochemical reaction occurs with the formation of β-Si5AlON7. Three zones of the structure formation caused by the temperature gradient in the bulk material as a result of the plasma exposure, are identified and studied. The first zone is directly irradiated by the plasma. The second is the transition zone, which locates between the first and third zones. The third is the thermal heating zone provided by the heat transfer from the irradiated zone.

The paper focuses on the influence of the water molecule rotation in a free interlayer space on the internal energy in tobermorite supercells. According to the molecular dynamics simulation, there are two types of insertion reactions of water molecule in a free interlayer space, which depend on the structure of tobermorite supercells studied in this paper. In the first type, the water molecule orientation does not induce a significant increase in the stability of supercell compositions. The second type is characterized by a significant hydration effect on the stability of these compositions, and the water molecule orientation in the free interlayer space strongly affects the supercell stability.