This paper presents the results of the effect of dispersion on the structural-phase state of the material for hydrogen storage of the Mg-Ni-Ce system. X-ray phase analysis and scanning electron microscopy studies have shown that the sequential use of mechanical synthesis and spark-plasma sintering methods ensures the formation of a stable and dense microstructure with a high content of the intermetallic phase Mg₂Ni. As a result of dispersion for 1 h, the sintered material was transferred to a finely dispersed state without changing the phase composition. Increasing the duration of dispersion to 2 h led to the formation of large agglomerates and the destruction of the material structure. For the first time, the dispersion technology was applied to materials of the Mg-Ni-Ce system, pre-sintered by spark-plasma sintering.

A comprehensive study of the structural–phase transformations and hydrogen desorption kinetics in the Mg₅₆Al₄₄ system was conducted using a multistage approach combining thermodynamic modeling CALPHAD, Thermo-Calc 2025a, mechanical synthesis (MS), spark plasma sintering (SPS), and subsequent dispersion treatment. Thermodynamic modeling revealed a stable existence region of the intermetallic compound Mg₁₇Al₁₂, exhibiting Cp-T anomalies at 303 and 351 °C that closely corresponded to the experimental DSC/TGA results. Microstructural analysis showed that varying the ball-to-powder ratio BPR 20:1 and BPR 30:1 determines the defect density, crystallite size 25–45 nm, and lattice strain 1.5–3.0 × 10⁻³, all of which directly influence the hydrogen desorption kinetics. For the samples synthesized at BPR 30:1, the onset temperature of hydrogen release decreased to 180–200 °C while maintaining a hydrogen storage capacity of 4.9 wt.%, accompanied by a reduction in the apparent activation energy of desorption from 92 to 74 kJ·mol⁻¹ according to the Kissinger method. The dispersion stage partially disrupted and redistributed the surface MgO layer, leading to a reduction in its overall contribution and improvement in structural homogeneity, rather than complete oxide removal. The combined MS-SPS-dispersion processing route enabled controlled nanostructure formation, reduced the hydrogen desorption temperature by approximately 100 °C compared to conventional MgH₂-based materials, and significantly enhanced the thermokinetic performance. These findings demonstrate that Mg-Al alloys are promising candidates for solid-state hydrogen storage systems with improved desorption kinetics and reduced activation barriers.

In this work, the results of the structural and phase state of LaNi₅-based alloys modified with Ti, Mn, and Co elements, obtained by mechanical alloying and subsequent spark plasma sintering, are presented. X-ray diffraction analysis was carried out to determine the phase composition, lattice parameters, microstrain, and average crystallite size, as well as to study the morphology and microstructure of the synthesized samples. It was established that the ball-to-powder ratio (BPR) and the milling speed affect the degree of intermetallic phase formation and the level of accumulated microstrains. The optimal mechanical alloying parameters make it possible to form the necessary precursor components for subsequent spark plasma sintering (SPS). It was determined that the SPS process effectively promotes the formation of intermetallic phases such as TiNi, LaNi₄Mn, LaNi₃Mn₂, and LaNi₄Co, ensuring high crystallinity and a reduction in defects accumulated during mechanical alloying. The morphology and microstructure of the samples with titanium, manganese, and cobalt additions showed that at the mechanical alloying stage, all systems are characterized by a dispersed and agglomerated structure, a wide particle size distribution, and a developed surface. After SPS, all series exhibited material consolidation and the formation of a dense matrix with distinct grain boundaries.

This article presents an analysis of the dependence of phase and morphological changes in the powder composition of the Mg-Ni-Ce system on the parameters of mechanical synthesis. During the mechanical synthesis process, it was found that, in addition to acceleration and duration parameters, the ratio of powder to milling balls has a significant influence on changes in the structural characteristics of the material. The results of the microscopic analysis showed that with a powderto-ball ratio of 1:10, the average particle size in the synthesized mixtures is 13.76 µm. At the same time, when applying a ratio of 1:30, the particle size decreases to 7.59 µm. It was established that magnesium is the primary phase in all samples. However, at a ratio of 1:30, the formation of the hexagonal crystal lattice of the MgNi phase and the emergence of the CeNi phase are identified.

This study investigates the effect of mineral additives of different natures, namely blast-furnace slag, fly ash, and bentonite, on structure formation, phase composition, microstructure, and physicomechanical properties of cement matrices. The analysis included measurements of mass change and linear shrinkage during hardening, determination of density and microhardness, X-ray phase analysis, and microstructural examination by scanning electron microscopy. It was found that the introduction of mineral additives reduced linear shrinkage from 6.06 mm for the control composition to 0.25 mm for the composition with blast-furnace slag, 2.31 mm for the composition with fly ash, and 1.01 mm for the composition with bentonite. The maximum density and microhardness values were obtained for the matrix with blast-furnace slag and amounted to 1.99 ± 0.03 g/cm³ and 39.95 ± 1.12 HV1, respectively, whereas the overall range of values for the investigated compositions was 1.52–1.99 g/cm³ and 30.2–39.95 HV1. X-ray phase analysis showed that the amorphous component varied from 61 to 78%, reaching its maximum value in the composition with blast-furnace slag, which is associated with the formation of poorly crystalline C–S–H and aluminosilicate phases. According to the SEM data, the average size of visible pore-like defects was 2.4 μm for the control composition, 1.4 μm for the composition with blast-furnace slag, 1.3 μm for the composition with fly ash, and 1.7 μm for the composition with bentonite. The most favorable combination of high density, microhardness, developed amorphous component, and homogeneous microstructure was established for the composition with blast-furnace slag. The obtained results can be used as a materials-science basis for the development of cement matrices intended for further studies on the immobilization of solid radioactive waste.

In this paper, we study the technology of producing a LaNi₅-based alloy by spark plasma sintering (SPS) for hydrogen storage. Preliminary mechanical activation and mechanical synthesis were carried out using lanthanum (La) and nickel (Ni) metal powders in mass ratios of 20:1 and 30:1. The prepared powder mixtures were placed in a graphite matrix with a diameter of 20 mm, pre-pressed and sintered on an ISKRA spark plasma sintering unit at a temperature of 1250 °C and constant pressure in a vacuum environment. X-ray diffractometry was used for phase analysis of the synthesized samples, as a result of which phase transformations and crystalline features of the alloy structure were determined. As a result, it was found that the LaNi₅ phase is formed. In addition to the main phase, La₂O₃ oxide was also detected, which indicates partial oxidation of the material. In addition, the morphology and microstructure of the material were studied using a scanning electron microscope, which allowed us to characterize the surface structure and particle size distribution of the obtained samples. The results of the study confirmed the effectiveness of the mechanical synthesis and spark plasma sintering method for obtaining a LaNi₅-based material for hydrogen storage and made it possible to determine the effect of synthesis parameters on the phase composition and microstructural characteristics of the obtained material.