This research aims to optimizing the synthesis of Ni–Ti–Cu alloys with shape memory effect (SME) through a combination of mechanosynthesis and spark plasma sintering (SPS). It has been established that the rotation speed (650/750 rpm) and the duration of mechanosynthesis (1–8 h) critically affect the phase composition and morphology of the powders. The speed of the formation of the intermetallic phase NiTi is limited at 650 rpm, whereas it intensifies defect accumulation and amorphization at 750 rpm. X-ray phase analysis and scanning electron microscopy confirmed that the optimal mechanosynthesis regime (8 h, 750 rpm) ensures: synthesis of target phases B2-NiTi and B19 ′ -NiTi; minimal crystallite size ( ∼ 109 Å); high chemical homogeneity ( ∼ 46 at% Ni, ∼ 42 at% Ti, ∼ 10 at% Cu). Subsequent SPS at 850–900 ° C and 49.2 MPa allowed for the production of dense samples. Sintering at 90 0 ° C after mechanosynthesis at 750 rpm ensured the predominance of the stable B2 austenitic phase, high microstructural homogeneity, and minimal porosity, which is critical for the reversibility of martensitic transformations. EDS analysis confirmed the chemical homogeneity ( ∼ 46 at% Ni, ∼ 42 at% Ti, ∼ 10 at% Cu) and the uniform distribution of elements. The results demonstrate the effectiveness of combining mechanosynthesis at an increased rotation speed and reduced duration with SPS for the formation of microstructures optimized for the requirements of shape memory alloy (SMA) materials.

This study investigates the control of the phase-structural state in Ni–45Ti–xCu (x = 5, 7 at.%) shape memory alloys fabricated via a shortened powder metallurgy route: mechanical activation → spark plasma sintering (SPS) → heat treatment. Compact samples were produced from mechanically alloyed powders (650–750 rpm, up to 5 h) and sintered at 900 °C. The structure and microstructure were characterized using X-ray diffraction (to identify B2/B19′/Ni₄Ti₃ phases and assess ordering) and SEM–BSE/EDS (to analyze morphology, porosity, and Ni-rich precipitates). Two post-processing treatments were applied: single-stage annealing (500 °C, 2 h) and a three-stage treatment (900 °C/30 min → water quenching → 300 °C/20 min). Mechanical alloying transformed the initial elemental powder mixture (fcc-Ni, hcp-Ti, fcc-Cu) into a supersaturated fcc-(Ni, Cu, Ti) solid solution with emerging NiTi phases, with a minimum particle size achieved after ~300 min at 750 rpm. SPS compaction yielded a high-density matrix consisting predominantly of the B2 phase. Single-stage annealing preserved B19′ martensite and Ni₄Ti₃ precipitates, particularly in the 5 at.% Cu alloy. In contrast, the three-stage treatment dissolved the Ni₄Ti₃ precipitates, suppressed the formation of B19′ and R phases, and stabilized a highly ordered B2 matrix. Increasing the Cu content from 5 to 7 at.% significantly enhanced the B2 phase fraction, reduced secondary nickel-rich phases, and improved structural homogeneity, evidenced by a continuous neck network and closed porosity. The optimized condition—7 at.% Cu combined with the three-stage annealing—produced a microstructure with >95% B2 phase, <1% Ni₄Ti₃, and ~98% relative density. This forms the prerequisite microstructural state for a narrow transformation hysteresis and high functional cyclic stability.

This work investigates the effect of titanium content and the duration of mechanical alloying on the structural and phase state of powder mixtures in the Ni–Al–Ti system. The initial mixtures of Ni₆₈Al₂₅Ti₇, Ni₇₂Al₂₂Ti₆, Ni₇₀Al₂₁Ti₉, and Ni₇₅Al₂₅ were subjected to high-energy milling in a planetary ball mill for 1–6 h. It was found that the addition of titanium accelerates the dissolution of components and promotes the formation of a supersaturated fcc Ni(Al,Ti) solid solution. The most pronounced effects were observed for the Ni₇₀Al₂₁Ti₉ composition, where after 6 h of alloying, the minimum crystallite size (11.3 nm) and maximum lattice strain (1.52%) were achieved. It is shown that titanium reduces the tendency for cold welding and promotes more uniform particle refinement. The optimal conditions for synthesizing a nanocrystalline solid solution with a homogeneous structure are a titanium content of 9 at.% and a mechanical alloying duration of 6 h. The resulting powders are promising for subsequent sintering and application in structural and heat-resistant intermetallic alloys and coatings.

Boron nitride is considered a promising material for solid-state hydrogen storage due to its high thermal and chemical stability up to ~1000 °C, depending on the atmosphere, as well as its ability to form defect-rich structures with enhanced sorption activity. Despite the growing interest in modified BN systems, systematic studies on the effect of multicomponent modification induced by the addition of carbon, titanium, and aluminum on the structural and phase evolution of boron nitride during high-energy mechanical alloying remain limited to date. In this work, the structural-phase and morphological changes in boron nitride-based composites modified by the addition of carbon, titanium, and aluminum, synthesized by high-energy mechanical alloying, were investigated. The structural state and morphology of the materials were analyzed using X-ray diffraction, scanning electron microscopy, particle size analysis, and thermal analysis. It is shown that mechanical alloying leads to a progressive breakdown of the layered hexagonal BN structure and the formation of an amorphous-like, defect-rich state without the formation of new crystalline phases. The main stage of amorphization occurs within 30–60 min, after which structural disordering reaches saturation. Increasing the mechanical alloying time to 120 min does not result in significant changes in the phase state; however, it is accompanied by a reduction in agglomeration and the formation of a more homogeneous powder morphology, characterized by narrower particle size distributions, smoother particle surfaces, and more uniform spatial dispersion of components. It was established that the nature of the added component significantly influences the kinetics of structural transformations: carbon accelerates amorphization, titanium intensifies fragmentation and defect accumulation, whereas aluminum exhibits a stabilizing effect. In multicomponent BN–C–Ti–Al systems, a synergistic combination of these effects is observed, leading to the formation of metastable, partially amorphous structures. Based on a comprehensive analysis of structural and morphological data, the optimal mechanical alloying time was determined to be 120 min, providing a saturated amorphous-like structural state combined with improved microstructural homogeneity. The obtained defect-rich boron nitride structures can be considered a promising basis for further studies in the field of solid-state hydrogen storage.

In this work, the influence of process control agents on the morphology and structural-phase state of powder mixtures of the Ti-Al-Nb system was studied. To improve the technique for grinding powder mixtures of the Ti-Al-Nb system in a planetary ball mill, two types of powders were prepared with the addition of process control agents based on stearic acid and liquid toluene. The process of grinding the compositions with the addition of agents was carried out at 550 rpm/m for 30, 60, 120, 180 minutes.During the studies, it was found that the evolution of particle morphologies using stearic acid and liquid toluene was similar. The effect of the agent as a process regulator of stearic acid on the evolution of powder morphology was greater than that of liquid toluene, since it inhibited the cold welding process of powders more effectively. During high-energy grinding using toluene for 120 and 180 minutes, undesirable carbide phases are formed.

Tungsten borides are promising superhard materials, but their mechanochemical synthesis requires prolonged processing, leaving the early and intermediate stages of mechanical alloying (MA) and the role of boron content largely unexplored. This study investigated the effect of boron content and high-energy MA duration (2–10 h) on the morphology, particle size distribution, and structural and phase evolution of W–B powder mixtures, comparing a near-stoichiometric W90B10 composition with a boron-excess W80B20 composition. Scanning electron microscopy, laser diffraction, X-ray diffraction, and TEM-EDS were used for characterization. The average particle size of W90B10 initially increased to 3.48 μm after 6 h and then decreased to 1.28 μm after 10 h, whereas W80B20 exhibited non-monotonic behavior, stabilizing at approximately 4.3 μm. With increasing MA duration, bcc-tungsten reflections broadened and weakened, indicating a highly disordered nanocrystalline state. Reflections of hexagonal WB₂ (crystallite size 12.5 nm) appeared in W90B10 after 8 h, whereas no crystalline boride phases were detected in W80B20 up to 10 h. TEM–EDS and SAED analyses revealed local compositional inhomogeneity and provided additional crystallographic support for the formation of nanocrystalline WB₂. These results show that boron content determines the kinetics of boride phase formation and the morphology evolution pathway during MA, identifying W90B10 as the more favorable composition for rapid nanocrystalline WB₂ synthesis.