This paper presents a review of a number of works devoted to the studies of high-entropy alloys (HEAs). As is known, HEAs represent a new class of materials that have attracted the attention of scientists due to their unique properties and prospects of application in hydrogen power engineering. The peculiarity of HEAs is their high entropy of mixing, which provides phase stability and flexibility in developing materials with given characteristics. The main focus of this paper is on the application of HEAs for solid-state hydrogen storage, their physicochemical and mechanical properties, and synthesis technologies. Recent advances in the hydrogen absorption properties of HEAs are analyzed, including their ability to efficiently absorb and desorb hydrogen at moderate temperatures and pressures. Prospects for their use in the development of environmentally safe and efficient hydrogen storage systems are considered. The work also includes a review of synthesis methods aimed at optimizing the properties of HEAs for hydrogen energy applications.

Bismuth is a promising and environmentally safe metal widely used in various industries, including electronics, medicine and metallurgy. Despite this, its production is associated with a number of technological difficulties due to the low content of bismuth in natural ores and its presence mainly as a by-product of lead processing. The present article is devoted to the study of the method of increasing the content of bismuth in lead alloys using oxygen oxidation. It is shown that lead, which has a high affinity for oxygen, is effectively oxidized and passes into the slag phase, whereas bismuth is concentrated in the metallic phase. Experiments were carried out at 650 °C using boric acid to lower the melting point of the slag and improve its flowability. As a result of five enrichment steps, the bismuth content in the alloy increased from 4.0% to 48.8%. The proposed method demonstrates high selectivity and economic efficiency, which makes it promising for industrial application. The results of the study can be used to develop more environmentally safe and energy-efficient technologies for bismuth lead enrichment, which is especially relevant in the context of growing demand for bismuth in various industries.

The article presents the results of a study on the influence of HVOF spraying parameters on the phase composition, mechanical properties, and adhesion characteristics of zirconium carbonitride (ZrCN) coatings. X-ray diffraction analysis of the ZrCN coatings revealed the presence of ZrCN, ZrC, ZrN, ZrO,Fe, and FeN phases, indicating a complex coating structure and possible oxidation and elemental diffusion processes. The formation of ZrC and ZrN is attributed to the thermal decomposition of ZrCN powder during the coating process, while the presence of the oxide phase ZrO is explained by the use of an oxygen-containing gas mixture during HVOF spraying. The microhardness of the ZrCN coatings reaches values in the range of 1500–1800 HV, depending on the spraying parameters. Adhesion test results showed that the maximum coating bond strength under tensile load was 7.49 MPa. Optimal coating characteristics were achieved at the following spraying parameters: substrate distance of 35–40 cm, propane pressure of 1.7 bar, air pressure of 2.6 bar, and oxygen pressure of 2.8 bar. These conditions allow the formation of a dense, wear-resistant coating structure with enhanced performance characteristics.

The effects of post-processing heat treatment on the structural and phase state and hydrogen sorption characteristics of an equiatomic TiZrNbVTa high-entropy alloy produced by mechanical activation and spark plasma sintering were investigated. The powder mixture was mechanically activated under argon and consolidated at 1450 °C. Two processing conditions were compared: SPS with a 7 min hold without subsequent treatment, and SPS with a 5 min hold followed by annealing at 1050 °C for 5 h. Phase composition was analyzed by X-ray diffraction. Hydrogenation was performed at 400–600 °C under a hydrogen pressure of 37–40 bar. Hydrogen content was evaluated using the SOAK kinetic method and inert gas fusion analysis with a RHEN-602 analyzer. Both materials were predominantly composed of a Nb-enriched body-centered cubic phase, whereas their secondary-phase compositions differed. After annealing, weak reflections tentatively attributed to ZrO₂ and TaO₂ appeared, whereas reflections previously assigned to Zr, V, and TiO₂ could no longer be resolved. According to the RHEN-602 measurements, the hydrogen content ranged from 1.12 to 1.37 wt.% for the SPS sample and from 0.64 to 2.08 wt.% for the SPS-HT sample between 400 and 600 °C. These results indicate that processing involving high-temperature annealing modifies the phase state and may enhance hydrogen uptake at 500–600 °C.