The study covers the possibility of WC-15Co ultrafine cemented carbide production from powder obtained by spark erosion (SE) of VK15 cemented carbide waste in water. As a result of SE in an oxygen-containing liquid (H₂O), the carbon content in the resulting powder decreases from 5.3 to 2.3 %. When the powder is heated to 900 °C in vacuum, the carbon content decreases to 0.2 % due to the presence of oxygen. The powder obtained consists of WC, W2C and Co phases. Particles have a dendritic structure consisting of newly formed tungsten-containing grains and cobalt interlayers. The controlled removal of oxygen and carbon replenishment in the resulting powder were carried out by heating in the CO atmosphere to t = = 900 °C. The processed powder has a required phase composition (WC + Co) and carbon content (5.3 %). Particles retain their spherical shape after carbon replenishment. WC grains in particles become plate-shaped with the space between them filled with cobalt. The average grain diameter is smaller than in the initial alloy. The vacuum sintering of the resulting powder at 1390 °C made it possible to obtain WC–15Co ultrafine-grained cemented carbide with an average WC grain diameter of 0.44 μm. It is several times smaller than the average grain diameter in the initial alloy (1.8 μm). Most grains retain their plate shape. The resulting alloy combines high hardness (1620 HV), increased fracture toughness (13.2 MPa·m^1/2) and strength (1920 MPa) due to its fine-grain structure and 15 % cobalt content. In terms of the set of its properties, this alloy is not inferior to analogues obtained by other methods.

The paper provides the results of simulating the hot die forging of porous powder preforms with active friction forces applied along the lateral surface of the deformable blank by means of internal cohesion in the die-material system. The study covers the evolution of relative density distribution over the blank cross section at different stages of deformation, stress-strain state and total strain force while varying the loading boundary conditions by changing the initial compression force applied to elastic elements that prevent the die from displacement. It is shown that active friction forces acting on the periphery of the forging adjacent to the die inner side result in areas with a significantly higher deformation intensity compared to deformations in the center of the blank volume. At the same time, the volume of the high deformation intensity area and maximum values of deformation increase with a decrease in the spring initial compression force and, accordingly, with an increase in the die displacement value during deformation. Automatic die displacement due to internal cohesion in the die-deformable material system leads to a decrease in the total deformation force, and with a decrease in the die displacement value during deformation, the deformation force increases.

The paper presents the results of studying the effect of the state of grain boundaries (formed in the consolidation of beryllium powders by vacuum hot pressing on the strength properties of sintered beryllium. Scanning electron microscopy and X-ray spectral microanalysis were used to study the dependences of the morphology, elemental composition and structure of a dispersion hardening phase - beryllium oxide – on the content of low-melting impurities at the grain boundaries of sintered beryllium. A new hypothesis is proposed to explain the difference in the morphology and structure of reinforcing particles based on the transition features of amorphous beryllium oxide to a crystalline state (devitrification) at the grain boundaries of metallic beryllium. It is theoretically substantiated and experimentally confirmed that the devitrification mechanism can be homogeneous or heterogeneous depending on the content and ratio of silicon and aluminum impurities. This difference leads to the formation of either finely dispersed high-strength reinforcing particles of beryllium oxide or large, lower-strength oxide clusters. Changes in the morphology and structure of reinforcing oxide particles at the metallic beryllium grain boundaries, in its turn, influence the dynamics of beryllium microstructure grain growth during vacuum hot forming and, ultimately, the effect of dispersed grain-boundary hardening of sintered n beryllium. The paper provides the statistically processed results of testing the mechanical properties of industrial hot-pressed blanks produced of less than 56 μm powders to determine the effect of various factors (the content of impurities, their ratio and particle size of the initial powders) on the strength properties of hot-pressed beryllium. The adequacy of the obtained regularities was evaluated using the approximation confidence coefficients and confirmed the conclusions made in the theoretical and experimental analysis of the research problem. The statistical studies substantiated a comprehensive quality indicator of initial powders in order to predict the strength properties of hot-pressed beryllium. The results obtained substantiate new possibilities for controlling the mechanical properties of sintered beryllium for various purposes.

The synthesis and sintering of the (AlN)_x(SiC)_1–x solid solution were studied under the conditions of SHS gasostatiс processing at high nitrogen gas pressures (up to 110 MPa). Phase formation during the combustion of aluminum and silicon carbide mixtures with the different amount of a combustible component (aluminum content is 35 to 60 wt.%) was studied. It was shown that the optimal amount of aluminum mixed with silicon carbide to obtain a single-phase solid solution (with the complete Al conversion to AlN and without SiC dissociation) is 45–50 wt.%. A mixture with 55–60 wt.% Al leads to excessively high temperatures, which in turn leads to the silicon carbide decomposition to Si + C elements. The optimal parameters for obtaining a dense material in one stage were determined. The measured porosity and density of materials obtained demonstrated that preforming is essential for the final density of samples containing 50 wt.% Al: maximum density was achieved at a preforming pressure of 10 MPa. It was found that the 5 wt.% yttrium oxide additive increases the material density by almost 10 %. A similar effect is also obtained by increasing the initial gas pressure from 80 to 110 MPa. The maximum density in this case reached 2.7 g/cm³, i.e. 83 % of the theoretical density. The total volumetric shrinkage of the material was 10 ± 0.5 %, and this indicator can be almost completely smoothed over by the 3 wt.% boron additive. The microhardness of samples was 2000 kg/mm².

The paper focuses on obtaining a heterophase powdered and sintered ceramics based on hafnium diboride and silicon carbide by combined self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The structure of the synthesized SHS powder consists of hafnium diboride grains and agglomerated polyhedral 2–6 μm silicon carbide grains. The powders obtained had an average particle size of ~10 μm with a maximum value of 30 μm. Phase compositions were identical for the ceramics sintered by hot pressing and the synthesized powder. The resulting compact featured by a high degree of structural and chemical uniformity, porosity of 3.8 %, hardness of 19.8±0.4 GPa, strength of 597±59 MPa, and fracture toughness of 8.8±0.4 MPa·m^1/2. Plasma torch testing (PTT) was carried out to determine the oxidation resistance under the influence of a high-enthalpy gas flow. The phase composition and surface microstructure of the compact after testing were investigated. The HP compact demonstrated an outstanding resistance to the high-temperature gas flow at 2150 °С and heat flow density of 5.6 MW/m2 for 300 s. A dense protective oxide layer 30–40 μm thick was formed on the surface of HfB₂–SiC ceramics during the plasma torch testing. The layer consisted of a scaffold formed by HfO₂ oxide grains with a space between them filled with SiO₂–B₂O₃ amorphous borosilicate glass. The HfB₂–SiC SHS composite powder was hot pressed to produce experimental samples of model bushings for the combustion chamber of a low thrust liquid rocket engine designed for PTT in the environment close to actual operating conditions.

The paper discusses ways to optimize the properties of pyrolytic chromium carbide coatings (PCCC) for different industries. PCCC applications include protecting surfaces of different parts and units made of various materials against corrosion, sticking, high temperatures, and various types of wear. Such versatility of PCCCs is explained partly by the peculiarities of their structure that is generally a «superlattice» of alternating relatively hard and soft layers of different composition and, accordingly, functional characteristics such as microhardness and Young modulus. These structures with specific periods and layer thickness ratios correspond to the maximum quality criterion of the optimal control theory (OCT) problem, an inverse problem stated on the class of solutions for a direct problem simulating specific interaction, e.g. abrasive wear. At the same time, the direct problem itself, e.g. an indentation description, is an incorrect inverse problem of mathematical physics, and it needs its own optimal strategy to be solved. This results in a hierarchy of optimization algorithms that can be used to obtain best PCCC functional properties. When an abrasive-wear type direct problem cannot be formalized, it is suggested to use a computational-experimental method elaborated by the authors that is also based on OCT. The main focus is on the improvement of the PCCC deposition technology for every specific application using the optimal control theory. To obtain PCCCs that meet these conditions, it is required to take into account the physical and chemical features of precursor pyrolysis as well as the effect of different additives or catalysts in the process development.

The main trends of modern developing magnetic microelectronics are miniaturization and speed, while ensuring efficient operation in the MHz and GHz frequency ranges of magnetic fields. Developing new magnetic materials featured by properties that ensure the implementation of these trends is the key fundamental and applied problem of materials science. In this regard, Fe-Me-X nanocrystalline soft magnetic alloys (Me is one of the metals from Group IVb of the Periodic Table, X is one of the N, C, O, B light elements) obtained in the form of films are of interest. As shown earlier by the authors of this article on Fe-Zr-N films, such films featuring by the Fe/MeX two-phase structure can provide a combination of high saturation induction (Bs), low coercive force (Hc), high hardness, and thermal stability of the structure. The films were produced by magnetron sputtering. The data obtained and published by the authors on the Fe–Ti–B films earlier indicate great prospects for their application in modern microelectronics. There are no any other published results of FeTiB film studies in the context of microelectronics applications. In this paper, we continue the studies of FeTiB films started earlier to identify the chemical and phase composition providing the level of properties required for film application in microelectronics. Nanocrystalline films containing 0 to 14.3 at.% Ti and 0 to 28.9 at.% B were obtained by DC magnetron sputtering. The phase-structural state of the films was studied by X-ray diffraction and transmission electron microscopy. All films are divided into 3 groups according to phase composition: single-phase (supersaturated solid solution of Ti in α-Fe), two-phase (α-Fe(Ti)/α-Ti, α-Fe(Ti)/TiB₂, α-Fe (Ti)/FeTi, α-Fe(Ti)/Fe₂B) and XRD amorphous. It is shown that XRD amorphous films feature by a mixed structure represented by a solid solution of α-Fe(Ti) with a grain size between 0.7 and 2 nm and an amorphous phase. A reasonable assumption is made on the amorphous phase enrichment by boron. A quantitative assessment of the α-Fe(Ti) phase grain size and its dependence on the chemical and phase composition of the films is given. The mechanisms of solid solution and dispersion hardening determine the grain size of this phase.

This paper provides the first part of the study on the magnesium effect on the structural phase composition, physical and mechanical properties of nanostructured aluminum-magnesium composite materials with the composition Al_xMg_y + 0.3 wt.% C₆₀ fullerene. Composite powders were obtained by the simultaneous mechanical activation of initial materials in a planetary ball mill in an argon atmosphere. It was found that the obtained powders have a complex hierarchical structure made up of 50–200 μm aggregates consisting of 5–10 μm strong high-density agglomerates, which in turn are a combination of nanoscale (30–60 nm) crystallites. It was found that the increase in magnesium concentration in the composite up to 18 wt.% makes it possible to obtain crystallites with an average size of less than 30 nm during mechanical activation, while the size of aggregates is less than 50 μm. The maximum solubility of magnesium in aluminum with a crystallite size of 30–70 nm during mechanical activation was 15 wt.% (17 at.%). Using the differential scanning calorimetry method, it was found that nanostructured composites undergo irreversible structural phase transformations during heat treatment in a temperature range of 250–400 °C: recrystallization, decomposition of the α-solid solution of magnesium in aluminum and formation of intermetallic β-(Al₃Mg₂), γ-(Al₁₂Mg₁₇) and carbide (Al₄C₃) phases. In addition, the Raman spectra contain peaks that, according to some sources, correspond to covalent compounds of aluminum with C₆₀ fullerene – aluminum-fullerene complexes. The data obtained will be used in further research to determine parameters for the thermobaric treatment of nanocmposite powder mixtures in order to obtain and test bulk samples.