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The defective substructure of polycrystalline bodies causes substructural hardening and mechanical properties. Perlite, which is the main structural component of rails, undergoes a significant transformation during deformation, which is accompanied by a number of processes. In this paper, the methods of modern physical materials science were used to study and analyze the defective substructure of perlite of lamellar morphology and the properties of rail steel subjected to destruction under deformation conditions by single-axis stretching of flat samples. It was established that the ultimate strength varies from 1247 to 1335 MPa, and the relative deformation to failure – from 0.69 to 0.75. The formation of three zones of the fracture surface was observed: fibrous, radial and shear zones. Their shape and sizes were analyzed. Deformation of rail steel is accompanied by destruction of cementite plates of perlite colonies and repeated release of nanoscale particles of tertiary cementite approximately 8.3 nm in size in the volume of ferrite plates. The main mechanisms of destruction of cementite plates are cutting and dissolution. The dislocation substructure is represented by a chaotic distribution of dislocations and their clusters. The scalar density of dislocations in ferrite increases from 3.2·1010 cm–2 in the initial state to 7.9·1010 cm–2 when it is destroyed. Deformation is accompanied by formation of internal stress fields, manifested in the form of bending extinction contours. The sources of stress fields are the interface of cementite and ferrite plates, as well as grain boundaries. Fragmentation of ferrite and cementite plates was revealed. The average size of cementite fragments is 9.3 nm. In fracture zone of the rail steel sample, rotation of perlite grains was noted, indicating the presence of a rotational mode of deformation. Electron microscopic images of cementite plates show a change in the contrast, which may be associated with the formation of Cottrell’s atmospheres.

The article presents the results of analysis of evolution of the defective substructure of rail steel pearlite with lamellar morphology under deformation by uniaxial compression. The strain hardening of the studied steel under such deformation has a multistage character. Deformation of steel is accompanied by fragmentation of pearlite grains, which intensifies as the degree of deformation increases and reaches 0.4 of the studied foil volume at ε = 50 %. Fragments formed in ferrite plates are separated by low-angle boundaries. It was established that the average sizes of ferrite plate fragments decrease from 240 nm (ε = 15 %) to 200 nm (ε = 50 %) with an increase in the deformation degree. Fragmentation of cementite plates was revealed. It was found that the size of the fragments varies within 15 – 20 nm and weakly depends on the degree of steel deformation. Fracture of cementite lamellae, proceeding by their dissolution and cutting by mobile dislocations, was discovered. Carbon atoms that have passed from the crystal lattice of cementite to dislocations are carried out into the interlamellar space and form particles of tertiary cementite, the size of which is 2 – 4 nm. In the process of steel deformation, an inhomogeneous dislocation substructure is formed, which is due to the deceleration of dislocations by cementite particles. It was found that an increase in the deformation degree is accompanied by a decrease in the scalar and excess density of dislocations, which may be due to the escape of dislocations into low-angle boundaries, as well as their annihilation. It was established that the sources of internal stress fields are the interfaces between pearlite grains and colonies, cementite plates in pearlite grains, particles of the second phase located in the volume of ferrite plates.

The study objective was to analyze the change in the morphology and microhardness of the AK5M2 alloy irradiated by an electron beam in various regimes. The authors modified the Al-5wt%Si alloy surface by an electron beam in the modes differed in the electron beam energy density (10, 20, 30, 40, and 50 J/cm2) and pulse durations (50 and 200 μs). The study identified that at electron beam parameters of 30 J/cm2, 200 μs, and 50 J/cm2, 50 μs, the maximum increase in microhardness to 860 MPa and 950 MPa was observed for each of the regimes, respectively. The microhardness value of the cast alloy was 520 MPa. Numerous micropores and microcracks characterize the irradiation surface morphology at beam parameters of 30 J/cm2, 200 μs. The material shrinkage during its high-speed crystallization can cause the formation of micropores. It is possible to assume that the generation of tensile stresses in a surface layer resulted from high cooling rates of a surface layer of the material from the molten state causes the formation of microcracks. The irradiation mode of 50 J/cm2, 50 μs leads to the complete dissolution of intermetallic and silicon particles in a surface layer; the crack density per surface area unit of the sample decreases against the regime of 30 J/cm2, 200 μs. The surface layer is characterized by the structure of high-speed cellular crystallization with the sizes of 500 to 800 nm formed in the volume of the grains that may cause an increase in the strength properties of the material.

Martensite and bainite are the most complex structures being formed in steel in heat treatment including the quantitative interpretation. On frequent occasions, the application field of these steels includes the operation at high static and dynamic compression stresses. The thorough and comprehensive analysis of the materials’ structure after different types of treatment enables to use them competently for the manufacturing of the parts and structures providing them with the necessary complex of physical and mechanical properties. The factor determining the mechanical properties of the materials are the structure of solid solution, presence of nano-dimentional particles of the second phases, dislocation substructure, types and location of various boundaries and internal stress fields. For successful control of the formation of structural phase states and mechanical properties of the material it is necessary to know the quantitative laws and the cold hardening mechanisms of steels of different structural classes at active plastic deformation. By methods of transmission electron diffraction microscopy the analysis of cold hardening of 38CrNi3MoV steel with martensite and 30Cr2Ni-2MoV steel with bainite structures at active plastic compression deformation to 26 % and 36 %, respectively, was done in the research. The contributions caused by intraphase boundaries, dislocation substructure, carbide phases, atoms of alloying elements and long-range stress fields are considered. It is established that the substructural hardening (caused by the internal long-range stress fields) and solid solution strengthening (caused by carbon atoms) give largest contribution to cold hardening of 38CrNi3MoV hardened steel. For normalization of 30Cr2Ni2MoV steel hardening also takes place at the expense of the internal stress field’s action, at the penetration of carbon atoms to the ferrite crystal lattice as well as at the structural fragmentation with the deformation degree higher than 26 %. The dislocation substructure and the particles of carbide phase make comparatively small contribution to the hardening of these steels. It is shown that the cause of bainite steel softening at large (more than 15 %) degrees of deformation is connected with the activation of deformation microtwinning process.

Martensite and bainite formed in steel on heat treatment are very complex structures, resisting quantitative analysis. Often such steels are used at high static and dynamic compressive stress. Thorough analysis of their structure after various types of treatment permits their effective use in manufacturing so as to ensure the required physicomechanical properties of the product. The properties of such materials are determined by the solid-solution structure; the presence of secondary-phase nanoparticles; dislocational substructure; the type and position of different types of boundaries; and internal stress fields. Successful control of structure and phase formation and hence of the mechanical properties of the material depends on a quantitative grasp of strain hardening of steels of different structural classes on active plastic deformation. In the present work, transmission diffractional electron microscopy is used to analyze the strain hardening of 38KhN13MFA steel with martensitic structure and 30Kh2N2MFA steel with bainitic structure in active plastic deformation (compression) by up to 26 and 36%, respectively. The contributions of strain hardening associated with intraphase boundaries, dislocational substructure, carbide phases, atoms of alloying elements, and long-range stress fields are considered. The main contributors to the strain hardening of quenched 38KhN13MFA steel are substructural hardening associated with internal long-range stress fields; and solidsolution strengthening associated with carbon atoms. For normalized 30Kh2N2MFA steel, the strain hardening may again be attributed to internal stress fields, the introduction of carbon atoms in the ferrite lattice, and also structural fragmentation when the strain exceeds 26%. The dislocational substructure and carbide particles make relatively small contributions to the hardening of such steels. The loss of strength of bainitic steel at deformation exceeding 15% is due to activation of deformational microtwinning.

The microstructure and microhardness distribution in the surface of low-carbon Hardox 450 steel coated with alloyed powder wires of different chemical compositions are studied. It is shown that the microhardness of 6–8 mm-thick surfaced layer exceeds that of base metal by more than two times. The increased mechanical properties of surfaced layer are caused by the submicro and nanoscale dispersed martensite, containing the niobium carbides Nb2C, NbC and iron borides Fe2B. In the bulk plates, a dislocation substructure of the net-like type with scalar dislocation density of 1011 cm−2 is observed. The layer surfaced with the wire containing B possesses highest hardness. The possible mechanisms and temperature regimes of niobium and boron carbides in surfacing are discussed.

Transmission electron diffraction microscopy is used to analyze strain hardening of steel with a bainitic structure. Contributions to strengthening are considered for lattice friction, interphase boundaries, dislocation substructure, carbide phases, alloying element atoms, and remote stress fields. It is established that substructural and solid solution strengthening make the greatest contributions. The reason for steel loss of strength with large degrees of deformation is connected with activation of deformation microtwinning.

Recent years have been marked by considerable increase in the use of high-strength steel—especially martensitic and bainitic steel—for the manufacture of key industrial components and structures. The high strength depends on strain hardening of the steel. It is important to understand the strain hardening of steel of different structural classes with active plastic deformation, in order to ensure specified structural and phase states and mechanical properties. In the present work, by transmission electron-diffraction microscopy, the evolution of the structure, the phase composition, and the state of the defect substructure is compared for steel samples with martensite and bainite structure in active plastic deformation to failure. After austenitization at 950°C (1.5 h) and subsequent quenching in oil (for 38KhN3MFA steel) and cooling in air (for 30Kh2N2MFA steel), multiphase structure (α phase, γ phase, and cementite) based on packet martensite (38KhN3MFA steel) and lower bainite (30Kh2N2MFA steel) is formed. Quantitative results for the structural parameters of steel in plastic deformation permit analysis of the distribution of the carbon atoms in the structure of the deformed steel. The points of localization of carbon atoms in the martensite (quenched 38KhN3MFA steel) and bainite (air-cooled 30Kh2N2MFA steel) are identified. Deformation of the steel is found to be accompanied by the destruction of cementite particles. For quenched martensitic steel, the total quantity of carbon atoms in the solid solution based on α and γ iron is reduced, while their content at structural defects is increased. The redistribution of carbon atoms in the bainitic steel with increase in the strain involves the increase in the quantity of carbon atoms in the α iron, defects in the crystalline structure, and cementite at the intraphase boundaries; and the decrease in the content of carbon atoms in the cementite particles within the bainite plates and the γ iron.

Transmission electron microscopy is used to reveal the formation of localized deformation channels on a nanoscale in 30Kh2N2MFA steel subjected to compressive deformation of 40% or more. The channels are found to be located mainly along the interfaces of neighboring bainite lamellae or along grain boundaries. The structure of the deformation channels, their sizes, and the change in their volume fraction with the strain are analyzed.

The microstructure evolution and properties variation of the surface layer of rail steel after passed 500 and 1000 million tons of gross weight (MTGW) have been investigated. The wear rate increases to 3 and 3.4 times after passed 500 and 1000 MTGW, respectively. The corresponding friction coefficient decreases by 1.4 and 1.1 times. The cementite plates were destroyed and formed the cementite particles of around 10–50nm in size after passed 500 MTGW. The early stage dynamical recrystallisation was observed after passed 1000 MTGW. The mechanisms for these have been suggested. The large number of bend extinction contours is revealed in the surface layer. The internal stress field is evaluated.This paper is part of a themed issue on Materials in External Fields.

Optical and transmission electron microscopy (TEM) methods are used for layer by layer comparative analysis of low-temperature reliability rails with increased wear resistance and contact-fatigue strength of the highest quality after bulk quenching and differential hardening by different regimes. Quantitative relationships are established for changes in structural parameters, phase composition, and dislocation substructure over the central axis and fillet at different distances from the running surface. The degree of structure and phase composition inhomogeneity and defective substructure is revealed. It is shown that with respect to structural component content and interlamellar distance the structure after bulk hardening compared with differential hardening is more uniform in a layer 2 mm thick and less uniform at a distance of 10 mm from the running surface. With respect to stress concentration density, the rail structure after bulk hardening (compared with differential hardening) is less uniform in a layer 2 mm thick and more uniform in a layer at a distance of 10 mm from the running surface.

Silumin of the eutectic composition is treated by a high-intensity electron beam and a multiple increase in material fatigue service life is revealed. The structure of the modified layer and the failure surface of silumin subjected to fatigue multicycle destruction tests are investigated by scanning electron microscopy. Factors responsible for an increase in its fatigue service life are established and analyzed.

By optic and transmission electron microscopy, the regularities of the transformation of structural-phase states, the defective substructure of the rail surface layer to the depth of 10 mm under long-term operation (passed gross tonnage 500 and 1000 mln ton) are determined. In the initial state the structure is presented by perlite grains with predominantly lamellar morphology, grains of a ferrite-carbide mixture and structurally free ferrite grains. It is shown that operation of rail steel is accompanied by a complete failure of lamellar pearlite grains in the 15 μm thick surface layer and the formation of a ferrite-carbide mixture with nano-size particles. The strain-induced transformation of steel leads to the increase in the scalar and excessive density of dislocations, the curvature-torsion value of the crystal lattice and the amplitude of internal stress fields.

By scanning and transmission electron diffraction microscopy method the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron sizes that are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed.

The evolution of the phase composition and the imperfect substructure of the 30Kh2N2MFA bainitic structural steel subjected to compressive deformation by 36% is quantitatively analyzed. It is shown that deformation is accompanied by an increase in the scalar dislocation density, a decrease in the longitudinal fragment sizes, an increase in the number of stress concentrators, the dissolution of cementite particles, and the transformation of retained austenite.

The impact of the Rostov NPP operation on the radiation characteristics of the location area is estimated based on the results of state monitoring of the radiation. The analysis performed allows the conclusion to be made that there is no relation between the Rostov NPP operation and the radiation factors of the atmospheric air.

Photothermal transformations of color centers in additively colored calcium fluoride crystals and in a colored crystal with a recorded hologram have been investigated. It is shown that the absorption spectrum of a colored crystal can be reconstructed within the entire transparency range of the matrix crystal by varying both factors affecting the sample—actinic radiation wavelength and temperature—as well as the duration of their effect. This possibility is important for the application of additively colored CaF2 crystals as a holographic medium.

The surface modification of the eutectic silumin with high-intensity pulsed electron beam has been carried out. Multi-cycle fatigue tests were performed and irradiation mode made possible the increase in the silumin fatigue life more than 3.5 times was determined. Studies of the structure of the surface irradiation and surface fatigue fracture of silumin in the initial (unirradiated) state and after modification with intense pulsed electron beam were carried out by methods of scanning electron microscopy. It has been shown, that in mode of partial melting of the irradiation surface the modification process of silicon plates is accompanied by the formation of numerous large micropores along the boundary plate/matrix and microcracks located in the silicon plates. A multi-modal structure (grain size within 30-50 μm with silicon particles up to 10 [mu]m located on the boundaries) is formed in stable melting mode, as well as subgrain structure in the form of crystallization cells from 100 to 250 [mu]m in size). Formation of a multi-modal, multi-phase, submicro- and nanosize structure assisting to a significant increase in the critical length of the crack, the safety coefficient and decrease in step of cracks for loading cycle was the main cause for the increase in silumin fatigue life.

Regularities of changes in structure-phase states and the defect substructure of rail surface layers up to 10 mm along the fillet in long-term operation (the gross tonnage 1000 mln tons) were determined by methods of transmission electron diffraction microscopy and by measuring microhardness. The possible reasons of the observed regularities were discussed. It was noticed that two competitive processes may proceed in rail operation: (1) cementite segregation followed by their carrying to the volume of ferrite grains or plates (in the pearlite structure) and (2) cutting, subsequent dissolution of cementite particles, transition of carbon atoms at dislocations (Cottrell atmospheres), and carbon atom transfer by dislocations into the volume of ferrite grains (or plates) followed by the formation of cementite nanoparticles. A qualitative analysis of rail hardening mechanisms at different distance from the tread surface along the fillet after long-term operation was done. It was shown that hardening had a mult...

Following the approach suggested by I. Kaj and M. Taqqu, we consider a stochastic model of teletraffic based on Poisson random measure. We show that under appropriate assumptions, the finite-dimensional distributions for the scaled workload process converge to those of a stable Levy process. Bibliography: 10 titles.

Quantitative analysis of defect and carbide subsystems evolution in medium-carbon bainitic steel subjected to compressive strain up to 36% was performed by means of transmission electron diffraction microscopy. Dislocation substructure and carbide phase parameters dependence on degree of deformation are identified, possible reasons of staging in their changes are discussed. It is suggested that the reason for bainitic steel softening at high (over 15%) degrees of deformation is activation of deformation microtwinning process.

The analysis of structure-phase states modification of silumin subjected to electron beam treatment with the following fatigue loading up to the failure is carried out by methods of transmission electron diffraction microscopy. The tribology and strength properties of silumin surface after electron beam treatment and fatigue tests are studied and hardness decrease, wear coefficient and friction coefficient increase with the growth of cycles number are revealed. The possible reasons of the tribology and strength properties of silumin surface layers decrease are discussed.

The purpose of the study was to evaluate the efficiency of fluography (FLG) as a technique for the timely detection of cases of pulmonary tuberculosis in an investigatory isolation ward. According to the WHO data, at early detection stages the bacteria-discharging persons should constitute about 80% of all cases. Analysis of the first FLG films made in 22,973 prisoners in 2005-2007 revealed abnormalities in 7.6% of the convicts and tuberculosis-associated changes in 77% of cases. Sputum smear luminescence microscopy and culture for Mycobacterium tuberculosis in 115 patients showed that the persons who discharged bacteria were 72.2% of the patients. The data suggest that FLG is highly effective in timely identifying cases of pulmonary tuberculosis.

The purpose of the study was to examine the implication of radiation and microbiological methods in the timely detection and diagnosis of pulmonary tuberculosis in untried prisoners in an investigatory isolation ward. Fluorographic films made in 12,298 convicts were analyzed. Abnormal fluorograms were revealed in 14 and 7.7% of the untried prisoners in 2005 and 2006, respectively; the changes were tuberculosis-associated in 70.2% of cases. Fluorescence microscopy and inoculation were used to carry out sputum tests for Mycobacterium tuberculosis in 41.1% of the convicts with abnormal fluorograms and complaints about productive cough. Early diagnosis of pulmonary tuberculosis was made by microscopy in 14.9% of the prisoners; the diagnosis of tuberculosis was verified by the inoculation test in 34.5% of negative microscopy patients. In the remaining patients, the diagnosis of tuberculosis was based on X-ray studies and the results of treatment.

It is shown that narrow-band transmissive and reflective holographic filters for the near- and mid-IR spectral region can be recorded in calcium fluoride crystals with photochromic color centers. It is established that the diffusion–drift hologram-recording mechanism can provide close to 100% spatial modulation of the color-center concentration. Based on the measured absorption spectra of the crystal, the dispersion of its refractive index in the indicated spectral range is estimated by means of the Kramers–Kronig relations, and the characteristics of transmissive and reflective holograms are calculated. It is concluded that the diffraction efficiency of such holograms can be increased by increasing the concentration of color centers formed in the calcium fluoride crystal at the additive-coloration stage.

The activities of a mass tuberculin diagnosis team improved with a phthisiopediatrician being included as its member. Team members' work quality standards have been developed: age-specific tuberculin sensitivity, the rates of infection with Mycobacteria tuberculosis in children aged 12-14 years were 29.3 +/- 2.9%; the annual risk of primary infection was 2.5 +/- 0.21%; the rate of hyperergy to tuberculin with qualitative drug prevention was 0.09%. This enhances the efficiency of BCG revaccination and drug treatment in Dispensary Registration Group 6 and stabilizes the incidence of tuberculosis in children with its rise in adults.