The present study focuses on investigating the evolution of phase transformations in the Mg-Ni-Ce system under the influence of mechanical synthesis (MS) and spark plasma sintering (SPS). Magnesium powder mixtures with different nickel and cerium contents (Mg-3%Ni-2%Ce, Mg-7%Ni-3%Ce, and Mg-10%Ni-5%Ce) were mechanically activated along with various grinding parameters. The X-ray phase analysis (XRD) has shown the successive stages of the phase formation in the MS process: from the initial components to the formation of intermetallic compounds of Mg₂Ni, Mg₁₂Ni₆, and CeMg₃. An increase in the intensity of mechanical treatment facilitated the accelerated destruction of the crystal lattice, the generation of defects, and the formation of new phases, as evidenced by the broadening and reduction in the intensity of Mg diffraction peaks. The subsequent SPS stage promoted the completion of phase transformations, structural stabilization, and the formation of a dense, multicomponent microstructure with a uniform distribution of intermetallic compounds. The observed average crystallite sizes ranged from 20 to 70 nm, depending on the processing conditions. The research results demonstrate the possibility of targeted control over the phase composition, opening new opportunities for the development of highly efficient hydrogen-absorbing alloys.

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.

Nanostructured tungsten–copper (W–Cu) composites are promising materials for high-heat-flux components and advanced thermal management; however, their processing is limited by a high positive enthalpy of mixing of ~35.5 kJ/mol and weak interfacial bonding. This study provides a thermodynamic and kinetic justification for a technological route intended for 70W–30Cu and 75W–25Cu (wt.%) composites using high-energy mechanical activation and spark plasma sintering (SPS). CALPHAD-type calculations identified a critical copper activity plateau a_Cu ≈ 0.33 at 950 °C in the W-rich range, which favors the retention of submicron grains of 200–300 nm by limiting the chemical potential driving force for coarsening. Kinetic modeling via DICTRA predicted the formation of metastable interfacial diffusion zones with a characteristic width of 20–90 nm during short SPS holding times of 150–300 s, enabling the transition from mechanical interlocking to metallurgical bonding. Based on these calculations, a processing window of 950–1050 °C is proposed to achieve a target relative density of ≥97% and electrical conductivity of 35–45% IACS. The results provide a predictive framework for the experimental synthesis of nanostructured pseudoalloys with optimized conductive networks and reinforced tungsten skeletons.

This work presents the results of phase equilibrium modeling in the La-Ni-Al system using the Thermo-Calc software. The aim of the calculations was to optimize the composition and sintering parameters of aluminum-alloyed materials to preserve the CaCu ₅ -type structure and ensure stable hydride-forming properties. Phase diagram sections were constructed for temperatures of 750–950 ℃ at aluminum concentrations ranging from 5 to 20 wt.%, and corresponding thermodynamic parameters such as Gibbs free energy and enthalpy were calculated. The results showed that at 5–10 wt.% Al, the LaNi ₅ phase field is preserved with a minimal amount of secondary phases, while at 15–20 wt.% Al, the formation of NiAl (BCC_B2) intermetallics and rare-earth compounds such as La ₂ Ni ₇ occurs, along with the appearance of a liquid phase. The Scheil solidification calculation revealed that when the critical aluminum threshold of 10 wt.% is exceeded, aluminum redistributes into the liquid phase, leading to the breakdown of the original structure and degradation of the material’s hydrogen storage properties. The obtained data enable the determination of optimal synthesis and alloying conditions for developing efficient next-generation metal hydride hydrogen storage systems.