Bulletin of the Siberian State Industrial University

Using plasma surfacing technology in a protective nitrogen alloy environment, a coating of approximately 9 ‒ 10 mm thick was applied to 30HGSA steel with a Mo ‒ Cr ‒ Co ‒ C powder wire. The structural and phase state and elemental composition of the contact transition zone of a plasma coating system (high-speed molybdenum steel) "substrate (medium carbon steel)" subjected to electron beam treatment have been studied by methods of modern physical materials science. The energy density of the electron beam is 30 J/cm², the pulse duration of the electron beam is 50 μs, the number of irradiation pulses is 10, and the pulse repetition rate is 0.3 s¹ (specify the units of measurement). It has been established that the formation of the coating is accompanied by the creation of an extended transition layer with a thickness of about 100 μs, which contains an α-phase, a γ-phase, and carbides of complex composition. It has been established that the transition layer after irradiation contains microcraters and microcracks, crushing it into sections of various sizes. After irradiation, a lamellar structure containing Me₆C carbide cementite particles was revealed in the volume of the transition layer. X-ray diffraction analysis showed that the contact zone directly adjacent to the coating contains grains of residual austenite reinforced with nanoscale Me₆C carbides.

A analysis of the effect of constant and pulsed magnetic fields of varying intensity on the deformation characteristics of metallic materials, mainly para- and diamagnets, has been carried out. It was found that exposure of samples in magnetic fields with an induction of 0.1 – 0.5 T leads to a redistribution of alloying atoms, a weakening of the bond of dislocations with point and extended defects of the crystal lattice, which causes a decrease in the microhardness of materials by 15 ‒ 25 % compared with the initial state. In the region of weak fields (10 ‒ 50 MT), a pronounced nonlinear dependence of the yield strength and relative elongation on the magnitude of induction was found, which indicates the high sensitivity of the macroplastic properties of metals to small values of magnetic action. For the Al – Zn – Mg – Cu alloy, treatment at a field of 1 Tl and in the temperature range of 110 ‒ 140 °C reduces the critical shear stress by 10 ‒ 15 % and intensifies the nucleation process of the n' phase, which is associated with a decrease in interfacial energy and activation of structural and kinetic processes. In the Ti – 6Al – 4V titanium alloy, the action of the 2 Tl field contributes to an increase in dislocation density by up to 60 %, an increase in microhardness by 8 % and elongation by up to 13 %, which is explained by the participation of spin-dependent transitions in plastic deformation mechanisms. The action of pulsed magnetic fields stimulates subgranular fragmentation and significant grain crushing, leading to an increase in the ductility of alloys up to 25 %. The data obtained indicate the high potential of magnetic fields as a controlled tool for regulating the kinetics of phase transformations, defect dynamics, and reducing energy barriers to plastic flow, which opens up new opportunities for integrating magnetic processing into modern industrial technologies for shaping and strengthening structural materials of various nature.

The widespread use of duralumin in aviation, transportation and other industries is due to its high strength characteristics, low density and good manufacturability during casting and pressure treatment. The alloy under consideration belongs to the class of structural materials based on aluminum, reinforced with additives of copper, manganese, magnesium and lithium. Its operational properties are largely determined by the modes of heat treatment and the composition of the curing elements. One of the key factors limiting the durability of duralumin in aggressive environments is the tendency to local corrosion, in particular to pitting, which in freshwater is assessed primarily by the depth of damage. The results of a comprehensive study of the corrosion-electrochemical characteristics of an alloy of the AlMg5.5Li2.1Zr0.15 system (an analog of duralumin) additionally alloyed with small additives of rare-earth metals (lanthanum, cerium, and praseodymium) are presented. The experiments were performed in a model 0.3% NaCl solution using a potentiostatic technique in a dynamic mode at a polarization rate of 2 mV/s. The technique included recording the potential of free corrosion, constructing anode and cathode polarization curves, determining the potentials of pitting formation, and calculating the density of the corrosive current. It was found that an increase in the exposure time of the samples in the electrolyte, as well as an increase in the content of lanthanum, cerium, and praseodymium in the alloy, leads to a significant shift in the stationary corrosion potential to the positive region. The most pronounced effect was observed for praseodymium. At the same time, a decrease in the density of the corrosive current was noted. Modification of the alloy with rare earth elements contributed to an increase in its corrosion resistance in a chloride-containing environment by 10 ‒ 20 % compared with the base composition. The data obtained indicate that the introduction of La, Ce, and Pr leads to the formation of a more heterogeneous and passive surface that slows down the anodic processes of metal dissolution. The results of the work are of practical importance for the development of new corrosion-resistant aluminum alloys designed to work in conditions of exposure to seawater and other chloride-containing media.

Research related to the assessment of the cyclic durability of the developed structural materials for medicine and technology is an urgent task. One of the promising areas of medical materials science is the development of biocompatible β-alloys based on titanium with a Young's modulus comparable to values for cortical bone tissue (2 ‒ 23 GPa), including ultrafine-grained (UMZ) alloys. The patterns of fatigue failure for biocompatible UMS titanium alloys with low modulus of elasticity for multi- and gigacycle fatigue modes have been poorly studied and require detailed analysis. A study of the features of the destruction of a biocompatible Ti ‒ 45 wt alloy has been performed. % Nb in the UMZ and coarse-crystalline (KK) state during gigacycle fatigue tests on the Shimadzu USF-2000 ultrasonic resonant loading machine. The UMZ alloy was obtained by the combined abc-pressing method with multi-pass rolling. It has been established that the formation of a multiphase UMZ structure in the Ti – 45 wt alloy. % Nb leads to an increase in the fatigue limit by 1.5 times in comparison with the CC structure. The fracture surface of alloy samples in UMP and CC states in the nucleation and crack initiation zones was studied by electron scanning and transmission microscopy. It was established that the morphology of the surface of the samples after the destruction of titanium in the CC and UMZ states is similar. The nucleation and propagation zones of the crack have a macrobursted structure consisting of facets and a dimpled microrelief. It is shown that as a result of the destruction during gigacyclic tests in the QC state of the Ti – 45 alloy by weight. % Nb has formed a cellular-mesh dislocation substructure, and in the UMZ state, a fragmented substructure.

Progress in the production of heat-resistant alloys, nuclear energy, and industrial high-temperature chemistry necessitates the use of materials capable of withstanding high temperatures, as well as improving the functional and operational characteristics (hardness, strength, wear resistance, corrosion resistance, and service life) of steels and cast iron. Existing compounds have low heat–resistant properties and a limited service life, increasing which is an urgent task that can be solved by modification. Modification is one of the effective and relatively inexpensive ways to change the structure of various industrial alloys. The most promising materials having a long service life and maintaining high hardness over a wide temperature range are carbides of refractory chemical compounds. Various ways of modifying refractory metals with carbides are considered. The characteristics of multilayer and single-layer coatings are presented. The substantiation of the modifying effect exerted on the structure of alloys by refractory chemical compounds of carbides is given. The results of modification of carbon structural steel with tungsten carbide showed an increase in the service life of steel by 70%. It is revealed that a high proportion of the carbide refractory phase grain ensures a small crystal size, which leads to higher hardness and strength of the coating. The analysis of the modified aluminum surface showed the dependence of the properties of the surface layer on the modes of the modification process. It has been established that tantalum carbide is prone to thermal destruction, eliminated by additional alloying. The presented approaches to modifying the surface of metals and alloys can be a solution to the problem of the lack of materials used when heated by high-temperature flows to temperatures exceeding 2000-2500 ° C under the influence of aggressive media.

The task of supporting large families is relevant all over the world and has been recognized in the Sustainable Development Goals formulated by the United Nations. A large family in Russia is a family with three or more children, and this status is maintained until the eldest child reaches 18 or 23 years of age in full-time education. A single criterion for having many children was legislated at the federal level in the context of the adopted course to improve the demographic situation in 2024 in order to ensure equal rights for such families in all regions. However, an analysis of regional tax benefits reveals significant disparities in their provision. The level of development, the amount of tax and other benefits provided for large families, as well as their disparities in the regions are assessed. Based on the data from the FTS website and regulatory legal acts, transport, land taxes and personal property taxes were considered. For a comparative analysis, seven regions with different levels of budget provision were selected according to RIA Rating statistics. As a result, a relationship was established between the level of well-being of families and the number and quality of tax benefits in the regions and the level of their economic development. It was revealed that the formal unification of the status did not provide real equality in tax support, which indicates the need to develop federal minimum standards of tax benefits for large families. The results of the study are relevant and can be used by legislative authorities to develop unified minimum standards for tax support for large families throughout the Russian Federation, to align social policy in various regions of Russia, as well as as a source for research.