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.

The present study shows promising approach to produce hydrogen-accumulated rechargeable intermetallic compounds (IMC) from three-component powder composition Ti-25Al- 25Nb (at%), through experimentally chosen best modes and combined technological processes. The study includes research results on the effect of mechanoactivation (MA) process and following spark plasma sintering (SPS) technique on structural phase state of intermetallic Ti-Al-Nb composites. It was revealed that upon activation of the initial powder mixtures during their machining, intermetallic phases are formed by the interpenetration of aluminum into titanium and niobium lattices with the formation of solid solutions (Ti, Al) and (Nb, Al). It is found out, that the combination of MA and SPS is good for producing fine-graded predicted micro-structures in Ti-Al-Nb system owing to the activation of particle surface and formation of intermetallic phases at the preparation stage of powder mixture using MA technique as well as due to the effect of fast consolidation using SPS. This points to the fact of prospect for creating metal hydrides by combining MA and SPS techniques that makes it possible to obtain fine-grained IMC containing fair amount of O-phase.

In this research, samples of an alloy with a bimodal structure were studied on the basis of a previously developed technology for obtaining hydrogen storage materials based on the Ti-Al-Nb system. The results of SPS of mechanically activated powder mixtures of the Ti-Al-Nb system at a temperature of 1300 °C make it possible to obtain an alloy with a predominantly bimodal structure. However, an insignificant presence of TiAl₃, AlNb₂ phases, and unreacted niobium is still observed in the structure. The mechanical properties of alloys of the Ti-Al-Nb system after sintering show abnormally low values of strength and ductility (less than 150 MPa). Two-stage heat treatment of alloys of the Ti-Al-Nb system leads to the decomposition of large precipitates of TiAl₃ with the formation of O-phase nuclei, as well as to the complete dissolution of unreacted niobium and AlNb₂ phases. Heat treatment of alloys of the Ti-Al-Nb system contributes to an increase in its strength by approximately 10 times (1310 MPa, MA-180), and ductility by 2 times (1322 MPa, MA-20). The surface fracture of samples obtained after testing is characterized by intergranular (intercrystalline) brittle fracture with “river” or “step” features.

The paper considers a method of tungsten surface carbidization using a beam-plasma discharge (BPD), which was implemented in a plasma-beam installation (PBI). The advantage of this method is to create conditions for chemical reactions and physical processes as close as possible to those possible in thermonuclear installations. The BPD makes it possible to generate plasma using different working gases. Methane was used as a plasma-forming gas. The working gas pressure in a chamber was (1,3–1,4)·10^–1 Pa. The temperature dependence of the carbidized layer formation on the tungsten surface under plasma irradiation was determined in the temperature range of 700 °C–1700 °C. The formation of tungsten carbides in surface layers was confirmed by SEM and x-ray diffraction analysis. It was found that interaction between tungsten and methane in a wide temperature range can proceed with simultaneous or sequential formation of the carbide phases W₂C and WC.

This paper presents the results of experimental studies of the interaction of helium plasma with a near-surface tungsten carbide layer. The experiments were implemented at the plasma-beam installation. The helium plasma loading conditions were close to those expected in the ITER divertor. The technology of the plasma irradiation was applied in a stationary type linear accelerator. The impact of the helium plasma was realized in the course of the experiment with the temperatures of ~905 °C and ~1750 °C, which were calculated by simulating heat loading on a tungsten monoblock of the ITER divertor under the plasma irradiation at the load of 10 MW/m² and 20 MW/m², respectively. The structure was investigated with scanning microscopy, transmitting electron microscopy and X-ray analysis. The data were obtained showing that the surface morphology changed due to the erosion. It was found that the carbidization extremely impacted the plasma–tungsten interaction, as the plasma–tungsten interaction with the carbide layer led to the carbon sputtering and partial diffusion towards to the depth of the sample. According to these results, WC-based tungsten carbide is less protected against fracture by helium than W and W₂C. An increase in temperature leads to much more extensive surface damage accompanied by the formation of molten and recrystallized flanges.

This paper reviews recent advances in the synthesis of cobalt-free high-strength tungsten carbide (WC) composites as sustainable alternatives to conventional WC-Co composites. Due to the high cost of cobalt, limited supply, and environmental concerns, researchers are exploring nickel, iron, ceramic binders, and nanocomposites to obtain similar or superior mechanical properties. Various synthesis methods such as powder metallurgy, encapsulation, 3D printing, and spark plasma sintering (SPS) are discussed, with SPS standing out for its effectiveness in densifying and preventing WC grain growth. The results show that cobalt-free composites exhibit high strength, wear and corrosion resistance, and harsh environment stability, making them viable competitors for WC-Co materials. The use of nickel and iron with SPS is shown to enable the development of environmentally friendly, cost-effective materials. It is emphasized that microstructural control and phase management during sintering are critical to improve a material’s properties. The application potential of these composites covers mechanical engineering, metallurgy, oil and gas, and aerospace, emphasizing their broad industrial relevance.