Industrial waste recycling is not only linked to significant environmental challenges but also to the recovery of material resources. Typically, these recovered materials are reused within the same technological niche where the waste was generated, often through remelting or adding them to the charge. This study presents an alternative approach that enables the production of a functional powder product from steel swarf during the recycling process, which can subsequently be utilized in the creation of powder metal matrix composites. The initial structure of the swarf, following the turning of a steel billet, was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis after a processing complex involving additional oxidation and grinding. This analysis aimed to assess the degree of transformation in the structural-phase state of the steel swarf during its processing. It was observed that the swarf post-turning exhibited a complex morphological structure with an uneven distribution of oxygen and carbon. The oxygen present in the initial state of the swarf was insufficient to form a noticeable volume of oxides detectable by X-ray diffraction. However, SEM revealed individual oxide inclusions, each no more than 5 µm in size, located sporadically. Additional oxidation followed by grinding in a vibrating mill altered the structure of the steel swarf, increasing the volume fraction of oxide phases. The study’s findings indicate that the resulting powder from recycled steel swarf is essentially a metal matrix composite with oxide inclusions based on an iron matrix, which holds potential for various future powder technologies.

The primary regularities in the formation of the structure and phase composition of Fe–Ti system materials, which are promising for hydrogen storage under explosive compaction of titanium and iron powder mixtures, are considered. It has been established that under a loading regime ensuring shock-wave compression pressure P = 11.5 GPa and heating in the falling shock wave to 777 °С, the powder mixture is compacted to an almost non-porous state due to the uniform plastic flow of particles in a direction perpendicular to the direction of shock compression. Under more severe loading conditions (P = 12.5 GPa and t = 831 °С), a monolithic state is also achieved, but the deformation character of the powder mixture component particles changes fundamentally: plastic deformation of the particles is localised in their surface layers and has a pronounced jet character with the formation of specific “vortices”. The influence of the plastic deformation mechanism of powder particles on the formation process of the metastable intermetallic phase Ti₂Fe with increased hydrogen capacity has been discovered. It has been established that solid layers of Ti₂Fe up to 20 µm thick are formed at the contact boundaries of iron and titanium particles only in the case of jet flows of surface layers of particles. It has been shown that the cause of this effect is the local heating of the contact areas to a temperature above 1085 °С, which according to the phase diagram of the Ti–Fe system, is the minimum temperature for the existence of a liquid phase in it. It has been demonstrated that an effective method for producing materials based on Ti₂Fe is the combination of explosive compaction of Fe and Ti powder mixtures and subsequent heat treatment with heating to 1100 °С (reactive sintering in the presence of a liquid phase).

The study presents the results of the dissolution-precipitation process and cobalt grain growth during liquid phase sintering of Cu–Sn–Co and Cu–Sn–Co–W powder materials. The samples were obtained by static pressing of mixtures of technically pure copper, tin, cobalt, and tungsten powders. The average particle size of cobalt was 1.6 µm, and tungsten was 20 µm. Some of the samples contained mechanically activated tungsten with an average particle size of 0.14 µm. Sintering of the materials was carried out in a vacuum at temperatures of 820 and 1100 °C for durations of 5, 20, and 120 min. The structure of the sintered materials was studied using scanning electron microscopy and optical metallography. Elemental distribution maps in the materials were obtained through X-ray microanalysis. The grain sizes of cobalt were measured using specialized software. The largest grain size was observed in the Cu–Sn–Co material: after sintering at the specified temperatures and durations, it ranged from 8 to 46 µm. It was found that the most intensive grain growth occurred within the first 20 min of sintering. The addition of tungsten powder to the Cu–Sn–Co material contributed to the formation of finer cobalt grains. This is explained by the fact that tungsten particles, possessing high surface energy, act as nucleation centers for cobalt crystallization from the liquid phase. Mechanical activation of the tungsten powder increases its free surface area and enhances the mass transfer of Co through the liquid phase to the W particles. This helps to reduce the deposition of material on large Co particles and prevent their growth. As a result, in the Cu–Sn–Co–W material containing mechanically activated tungsten, the minimum average cobalt grain sizes were obtained, ranging from 3 to 25 µm.

The development of new hard magnetic materials (HMM) is crucial for meeting the ever-increasing demands of industry. Today, the advancement of energy, electrical engineering, and instrumentation sectors requires manufacturers of HMM products to enhance the energy efficiency and power of devices while reducing their size and weight, which increases scientists’ interest in these alloys. Among HMM, magnets derived from rare-earth elements such as Sm and Nd (Nd₂Fe₁₄B, SmCo₅, Sm₂Co₁₇) possess the highest magnetic energy at smaller sizes and weights. Alloys based on the Fe–Cr–Co system offer the best reliability, strength, corrosion resistance, and manufacturability, making them particularly in demand among HMM. Creating a magnet based on two alloying systems, Sm–Co and Fe–Cr–Co, may yield a material with unique properties that combine the advantages of both systems. This study investigates the powder hysteresis alloy 22Kh15K4MS (22 % Cr–15 % Ni–4 % Mo–Co–Si) doped with the rare-earth magnet KS25DTs in amounts ranging from 1.5 to 9.0 %. The microstructure, transformation kinetics, phase composition, and magnetic properties of the developed alloys were examined. It was found that the magnetic characteristics of the alloys depend on the concentration of the rare-earth magnet additive and the thermal treatment regime. It was demonstrated that the introduction of 3 % KS25DTs achieves the maximum magnetic properties of the alloy: H_c = 55.6 kA/m, B_r = 1.33 Tl, (BH)_max = 41 kJ/m³. The combination of the developed alloy composition and the thermal treatment regime allows for an increase in the rectangularity coefficient of the magnetic hysteresis loop (K_l) – one of the most important characteristics of precision hysteresis electric motors.

The possibility of dispersion strengthening of powder high-speed steel R6M5K5 with MoSi₂–MoB–HfB₂ heterophase ceramics particles was investigated. A mechanically alloyed powder mixture with an average particle size of d = 10 µm was used as the base material; the ceramic powder additive (d = 5 µm), obtained by the SHS method, was also used. Mixing was carried out in a high plane­tary ball mill. As a result, powder mixture particles with sizes of 2–25 µm were obtained, close to spherical in shape, with larger particles being agglomerates. Cold pressing and sintering were performed, achieving a density of up to 92.7 % and a hardness of 62 HRA, as well as hot pressing with a density of 97.2 % and a hardness of 65 HRC. The hot-pressed billet had a bending strength of 1141 MPa and a compressive strength of 2157 MPa. The prospects of using heterophase ceramics as a strengthening additive was shown, which contributes to lowering the temperature of the liquid phase formation and creates a pronounced heterogeneous microstructure, similar to the microstructure of metallic glass materials. The matrix is a solid solution based on iron (with an average grain size of 14–34 µm) with a network of eutectic carbide Me6C and ceramic additive inclusions in the form of HfO₂, SiO₂, and HfSiO₄ compounds. This provided a twofold reduction in wear during tribological tests against a counterbody made of VK6 hard alloy. The obtained composite material, demonstrating high red hardness, may find application in the production of wear-resistant products operating at temperatures up to 630 °C.

This study focuses on the development of high-temperature oxidation-resistant coatings within the Zr–Mo–Si–B system. It addresses the deposition processes using direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS). The research includes an analysis of gas discharge plasma, investigation of the coating structure, and determination of the mechanical properties and high-temperature oxidation resistance of the resulting coatings. The coatings were found to be X-ray amorphous, characterized by a dense, defect-free structure with a uniform distribution of elements throughout their thickness. All coa­tings demonstrated high oxidation resistance at temperatures of 1100 and 1300 °C. The transition from DCMS to HIPIMS mode resulted in a 16–21 % reduction in oxidation depth at 1300 °C. The coating obtained via DCMS exhibited the greatest thickness and the best oxidation resistance at 1500 °C. The high-temperature oxidation resistance of the coatings is attributed to the formation of a protective surface oxide film of Si:B:O, with dispersed nanocrystallites t-ZrSiO₄ and m-ZrO₂ phases.

The TNM-B1 + Y₂O₃ alloy powders obtained by the method of self-propagating high-temperature synthesis were studied. The influence of particle processing parameters in thermal plasma, generated by a DC (direct current) arc plasma torch, on the morphology and structure of spherical particles was considered. It was established that plasma treatment significantly changes the shape of the particles and allows obtaining a product with a high degree of spheroidization (from 88 to 97 %), which depends on the plasma stream temperature, the composition of the plasma-forming gas, and the amount of processed material. Using hydrogen-containing thermal plasma, the degree of spheroidization can reach 99 %. At the same time, the concentrations of impurity oxygen decrease from 0.8 to 0.13 wt. %, nitrogen decreases by 2 times, and the concentration of hydrogen significantly drops. Studies were conducted to develop selective laser melting regimes, resulting in samples with minimal defects. The optimal volumetric energy density of the laser was 40–50 J/mm³. The gasostatic treatment process allowed achieving almost complete uniformity of the samples’ structure and the absence of pores. Additionally, thermal treatment at t = 1380 °C and τ = 120 min contributed to the transformation of the initial equiaxed structure of the alloy into a lamellar one. According to the results of thermomechanical tests under the scheme of uniaxial compression in the temperature range from 800 to 1100 °C, it was established that the alloy with a lamellar structure after selective laser melting, hot isostatic pressing, and thermal treatment has increased strength values by 80–100 MPa compared to the globular structure. The mechanical properties of the alloy with a lamellar structure at t = 800 °C are: modulus of elasticity E = 115.2 GPa, yield strength σ_0.2 = 528 MPa, compressive strength σ_u = 1148 MPa, and at t = 1100 °C: E = 48.2 GPa, σ_0.2 = 98 MPa, σ_u = 149 MPa.

Shut-off and control valves are essential components in liquid and gas transportation systems; therefore, their reliable operation depends on the quality and properties of their surface parts. One method to enhance these properties is ion nitriding, which is actively used in Russia, Israel, Bulgaria, Belarus, Austria, and other countries. This method is easy to manage and control, is universal for all types of steels and alloys, is environmentally safe, ensures dimensional and surface finish accuracy, and improves the operational pro­perties of parts. This paper presents summarized results of studies on the formation of modified layers on steels used in valve manufacturing. The steels of grades AISI 420, AISI 301, AISI 431, and AISI 321 were strengthened by ion nitriding. For the first time, comparative data obtained on equipment from different manufacturers are presented. A comprehensive metallographic analysis, durometric analysis, and hardness distribution assessment across the depth of the modified layer were conducted during the study. It was found that steels with more than 12 % Cr form a clearly defined diffusion layer, which appears dark after etching with a 4 % nitric acid solution. However, the overall depth of the layer, as assessed by the distribution of microhardness into the depth of the part, is 20–40 % greater than revealed by the microstructure. The surface microhardness after ion-plasma nitriding increased fivefold in the AISI 301 steel. Thus, strengthening parts of shut-off and control valves using this method addresses the issue of rapid surface wear. By modifying the surface, the operational properties of parts can be enhanced, ensuring the uninterrupted operation of the pipeline system.