The Ukrainian VELTA company has developed and patented a novel technology for producing titanium metal powder through a two-stage reduction of titanium dioxide, offering an alternative to currently widespread titanium powder production methods. The key feature of the technology is the use of titanium oxide as the feedstock material, in contrast to the conventional Kroll process, which relies on titanium tetrachloride. Titanium dioxide powder is formed into feedstock elements with a specific shape, structure, and strength. The oxide constituting these elements is reduced in two stages. The first stage consists of reduction using metallic magnesium vapor and the second stage involves final deoxidation using calcium vapor. In addition to the production of pure metallic titanium, the proposed process can be employed to obtain titanium alloy powders by reducing titanium dioxide together with oxides of doping elements. The resulting powder is characterized by a low content of interstitial oxygen, nitrogen, and carbon atoms, at levels not exceeding the standard values for Ti Grade 1. The typical powder used in this study exhibits a broad particle-size distribution with a D50 of approximately 50 μm and consists of compact, irregularly shaped particles along with a significant number of very fine, nearly spherical particles smaller than 2 μm. Classification of the powder into two fractions employing an inexpensive sieving technique makes it suitable for various powder metallurgy applications. When separated into fractions below and above 45 μm, the fine fraction accounts for approximately one-third and the coarse fraction for two-thirds of the original powder weight. Previous studies have shown that the fine fraction (<45 μm) is suitable for metal injection molding (MIM). The aim of this study is to determine the suitability of VELTA’s >45 μm powder fraction for producing compact titanium via the press-and-sinter method.
To address the "cyan gap" issue in white light-emitting diodes (WLEDs), a novel Eu2+-doped θ-Al2O3 cyan-emitting phosphor (θ-Al2(1–x)O3 : xEu2+ (0.06 ≤ x ≤ 0.22)) was synthesized via the high-temperature solid-state reaction. The results indicate that all samples exhibit a pure monoclinic phase structure, with Eu2+ doping causing no phase transformation in the host lattice. The phosphor particles display uniform morphology and an average particle size of approximately 0.39 μm. Photoluminescence analysis reveals that the material exhibits strong absorption in the 300–420 nm range, enabling effective excitation by near-ultraviolet LED chips. The dominant emission peak is located at 500 nm, which precisely covers the cyan spectral gap. Gaussian fitting further deconvolutes the emission into two sub-peaks at 468 nm and 510 nm, attributed to Eu2+ occupying the Al(2) octahedral sites and Al(1) tetrahedral sites, respectively. Thermal stability tests demonstrate that the phosphor retains 81.78
Within the framework of the CALPHAD method, vertical radial sections were calculated using the database developed by, reflecting phase transformations involving the liquid (L), fcc (A1), and bcc (A2) phases of the Cu–Cr–Fe–Co–Ni system over the range from liquidus temperatures to 1000 K. The calculations show that the equiatomic alloy and alloys with near-equiatomic compositions are two-phase, formed by the fcc1 phase depleted in copper and the fcc2 phase enriched in copper. In these alloys, a precipitation-strengthened fcc structure can be produced, with the primary grains formed by the fcc1 phase and with the strengthening dispersed particles formed by the fcc2 phase. The composition of these alloys corresponds to the stabilization condition due to the high-entropy effect. The experimentally determined phase composition, chemical composition of the phases, microstructure of the as-cast and annealed alloys, and phase transition temperatures in the as-cast alloys are in full agreement with the sections of the Cu–Cr–Fe–Co–Ni phase diagram modeled within the CALPHAD method. The lattice parameters of the fcc phase are governed by the combined influence of the copper-to-chromium and iron-to-cobalt ratios. The (xCu/xCr)·(xFe/xCo) factor is proposed to unite them and allows to describe the lattice parameters by a single dependence. The microhardness of the matrix fcc phase in the as-cast and annealed alloys indicates that the matrix of these high-entropy alloys is quite soft and requires strengthening, whose possibility is supported by the present calculations. The thermodynamic database used for the calculations opens the way to a targeted selection of the optimal composition of precipitation-strengthened high-entropy alloys in the Cu–Cr–Fe–Co–Ni system and to determination of technological conditions for their production.
Laminated composites, consisting of multiple materials with distinct properties arranged in layers, are designed to combine attributes like high strength, low density, and excellent fracture toughness. These materials can be tailored to specific requirements by adjusting the number and composition of layers. Inspired by biomimetic designs, such as nacre, the development of graphene oxide-polydopamine (GO-PDA) nanocomposites has improved material properties. Fabrication methods for these composites, particularly in metal/metal and metal/ceramic combinations, include diffusion bonding, roll bonding, and casting. However, challenges such as high production costs and complex preparation processes hinder the development of metal/ceramic laminated composites. This study focuses on a metal-ceramic composite matrix reinforced with boron carbide (B4C) in aluminum alloys and investigates semi-continuous casting methods for fabricating Al/(7075–B4C)/Al laminated composites. The composites exhibit excellent mechanical properties, including high hardness, good impact energy absorption, and resistance to projectile impact.
Epoxy resin (EP) was used as the matrix, with glass fiber (GF) and boron nitride (BN) as reinforcements to prepare GF/BN/EP composites for industrial components under complex service conditions. GF/BN/EP composites with BN contents of 0, 0.3, 0.6, 0.9, and 1.2 wt.
The synthesis of TiC micro- and nanofibers by chemical vapor deposition from titanium tetrachloride and carbon-containing substances such as toluene and carbon tetrachloride, using Fe, Co, Ni, and Al catalysts, in the temperature range 1000–1200°C was studied. The optimal temperature ranges for the synthesis of TiC micro- and nanofibers were found to be 1000–1100°C with titanium tetrachloride and toluene as the carbon source and 1150–1200°C with titanium tetrachloride and carbon tetrachloride, which is consistent with the thermodynamic calculations. Nickel was identified as the most suitable catalyst for the synthesis. The TiC micro- and nanofibers grew through the vapor–liquid–solid mechanism. The TiC nanofibers were predominantly synthesized at 1000–1100°C, while microfibers with diameters reaching several micrometers were produced at higher temperatures. When nickel was used as the catalyst, the fibers grew in the form of tufts or needles. Thickened regions, microcrystals, and nanofibers developed on individual TiC microfibers. For the first time, rod-like phases were produced by chemical vapor deposition on an aluminum substrate, which can be interpreted as the MAX Ti3AlC2 phase. When iron powder was used as the catalyst, a two-dimensional titanium carbide phase grew, regardless of the carbon source. Dew-like droplets were formed on titanium carbide fibers grown on nickel or cobalt catalysts. Their composition can be attributed to the corresponding eutectics in the Ti–Ni and Ti–Co systems.
The electrochemical hydrogen sorption properties of electrodes produced from alloys without vanadium, ZrNi1.2Mn0.5Cr0.3 (1), and with different vanadium contents, ZrNi1.2Mn0.5Cr0.2V0.1 (2), ZrNi1.2Mn0.45Cr0.2V0.15 (3), ZrNi1.2Mn0.4Cr0.2V0.2 (4), and ZrNiMn0.5Cr0.2V0.5 (5), without catalytic additives were studied in galvanostatic and potentiodynamic modes. The effect of temperature and discharge rate on the hydrogen sorption behavior of alloys with different contents of the Zr7Ni10 phase was examined. This phase had a decisive influence on the kinetics of electrode processes for ZrNiMnCr(V) alloys, and its content decreased from 28 vol.
The high-temperature flow behavior and thermomechanical processing conditions are fundamental requirements for evaluating Ti alloys in the current context of lightweight, high-strength structural materials. Considerable work has been carried out on the correlation between heat treatments, microstructure, and properties of the Ti52Nb19Zr15Mo14 and Ti6321 alloys. Workability was evaluated under various heat-treatment conditions that allow α to precipitate. However, processing maps determine stability and instability regimes that impact deformation behavior at elevated temperatures. However, the impact of workability on Ti6321 and Ti–Nb–Zr–Mo alloys has not been explored. A high-temperature hot deformation test at 700 to 1000°C and a strain rate range of 0.01 to 10 s–1, with a constant strain of 0.3, was employed to characterize the hot flow behavior of Ti alloys. The processing map showed a high peak power dissipation efficiency (η = 56
Bonding jumpers are critical aircraft components that ensure electrical continuity between structural elements and protect against lightning-induced failures, and they must comply with the EN-4199 aviation standard. Despite their safety-critical role, the design, fabrication, and performance evaluation of bonding jumpers, particularly domestic manufacturing, have not been systematically investigated in the literature. In this study, tin-coated copper wires were braided to fabricate bonding jumper specimens and benchmarked against imported bonding jumpers used in passenger aircraft. All specimens were characterized by FESEM–EDX analysis, tensile testing, and electrical resistance measurements. Domestically manufactured bonding jumpers exhibited tin coating ratios, tensile strengths, and electrical resistance comparable to those of imported specimens. In addition, catalog data from leading international manufacturers were evaluated, revealing that the manufactured specimens achieved equivalent or superior performance in both mechanical and electrical properties. These findings represent the first systematic study in the literature to comprehensively investigate the design, fabrication, and multi-parameter performance characterization of bonding jumpers, thereby establishing a scientific foundation for future research and qualification studies in this field.
X-ray diffraction was employed to examine the phase composition and determine the amount of a specific phase (quantitative phase composition) in the ZrNi1.2Mn0.5Cr0.3 (1), ZrNi1.2Mn0.5Cr0.2V0.1 (2), ZrNi1.2Mn0.45Cr0.2V0.15 (3), ZrNi1.2Mn0.4Cr0.2V0.2 (4), and ZrNiMn0.5Cr0.2V0.5 (5) alloys. The dependence of the quantitative phase composition on the chemical composition of the alloys, on the vanadium amount in our case, was established. Alloys 1–4 with a lower vanadium content ( 2.5–5 wt.
A thermodynamic database for the liquid (L), fcc (A1), and bcc (A2) phases of the Cu–Cr–Fe–Co–Ni system was developed using the CALPHAD method. The database includes model parameters for the thermodynamic mixing functions of binary and ternary boundary systems. The database was developed to model the temperature and composition ranges for high-entropy fcc alloys existing in the Cu–Cr–Fe–Co–Ni system at temperatures exceeding 1000 K. As a first application, phase diagrams for boundary quaternary systems were calculated, and it was shown that each of them was characterized by fcc fields extending in temperature and composition. In the Cu–Fe–Co–Ni system, the fcc phase undergoes binodal decomposition, and the formed two-phase region grows with decreasing temperature, occupying most of the composition tetrahedron. In the Cr–Fe–Co–Ni composition space, the fcc phase is predominant, while the bcc and fcc + bcc regions are located along the Cr–Fe edge. In quaternary systems containing copper, conditions exist for the separation of equilibrium and supercooled melts over a wide composition range. The results of the calculations indicate the potential of the examined systems for producing single-phase high-entropy alloys, precipitation-strengthened alloys, and composite materials with a frozen emulsion structure.
Isoperibolic calorimetry was employed for the first time to study the mixing enthalpies of Al–Lu–Cu melts along four radial sections with xAl/xLu = 0.42/0.58 and 0.76/0.24 and with xCu/xLu = 0.35/0.65 and 0.7/0.3 at 1780 ± 3 K. When aluminum was added to the CuxLu1–x melts, the thermal effect of its dissolution increased. This was due to the formation of strong bonds between aluminum and lutetium. In the other two sections, on the contrary, when copper was added to the AlxLu1–x melts, the strong bonds between aluminum and lutetium were broken. Therefore, the integral mixing enthalpies of these melts hardly changed up to xCu = 0.4. Using the formation enthalpies for liquid alloys and compounds in the Cu–Lu system known from the literature, all thermodynamic properties of melts, associates in melts, and intermetallics were optimized and calculated with the ideal associated solution (IAS) model. The calculated activities of components in melts of this system exhibited moderate negative deviations from ideal solutions. The IAS model was also used to calculate temperature–composition dependences of the Gibbs energies, enthalpies, and entropies of formation for melts and temperature dependences for intermetallics to further determine the liquidus curve of the system phase diagram. As a result, complete information was obtained on the thermodynamic properties of all phases and the liquidus curve of the Cu–Lu phase diagram, which agrees with the one known from the literature. The reliable thermochemical properties of melts in the boundary binary Al(Cu)–Lu and Al–Cu–Lu subsystems were presented as Redlich–Kister polynomials to calculate the same data for the studied ternary melts with the analytical Redlich–Kister–Muggianu model. Comparison of the measured and calculated mixing enthalpies for these melts showed that our data and those found with the analytical Redlich–Kister–Muggianu model without the ternary contribution were consistent within the experimental error. The extreme value of the integral molar enthalpy of melts in the ternary Al–Cu–Lu system was –37 ± 4 kJ/mol and corresponded to the Al0.6Lu0.4 melt, i.e., the boundary Al–Lu subsystem provided the main contribution to the interaction energy between dissimilar atoms in these ternary melts.
The Alloy Phase Diagram International Commission (APDIC) was established in 1986 in Orlando, Florida, USA, pursuant to a Memorandum of Understanding. As of 2025, 18 representatives from 27 countries around the world participated in APDIC activities. APDIC members independently carry out their individual scientific programs and participate in annual meetings to discuss pressing issues related to coordinating their activities. Since 1994, the Ukrainian Phase Diagrams and Thermodynamics Commission has been an integral part of APDIC. As part of the Ukrainian Commission's annual report, at the APDIC meeting on May 30, 2025, information was presented on the results of Ukrainian scientists' activities in this field in 2024. It is presented in the form of a table with data on the studied systems and the obtained results, along with a list of references to published papers. Scientists from the Frantsevich Institute for Problems of Materials Science (National Academy of Sciences of Ukraine, Kyiv), Taras Shevchenko National University of Kyiv (Ministry of Education and Science of Ukraine, Kyiv), and Donbas State Engineering Academy (Ministry of Education and Science of Ukraine, Kramatorsk) provided relevant information to the Ukrainian Commission.
A new class of materials—high-entropy alloys—is characterized by the presence of atoms with different properties in the absence of a dominant element. In accordance with the self-organization law, this should give rise to new relationships that are unique to high-entropy alloys. The high hardness of high-entropy alloys prompted research into their properties in coatings. The hardness of high-entropy metallic coatings reaches nearly 20 GPa. The mechanical properties of as-cast high-entropy alloys are influenced by lattice distortion (resulting from differences in the atomic radii of elements) and lattice parameter. The relationship between the lattice parameter and distortion and the elastic modulus, hardness, and normalized hardness of high-entropy alloys was analyzed in both as-cast alloys and metallic coatings. The dependence of the elastic modulus and hardness on the lattice parameter was established for as-cast alloys and associated coatings. Coatings with a bcc phase exhibit a slight decrease in the lattice parameter compared with the as-cast state. This is accompanied by a proportional increase in the elastic modulus. At the same time, the elastic modulus of fcc-phase coatings approaches the value found with the rule of mixture as the lattice parameter decreases to the calculated value. The absence of a proportional relationship between the hardness and distortion in as-cast alloys and metallic coatings was demonstrated. The effect of distortion on the normalized hardness (the ratio of hardness to effective elastic modulus) was identified for as-cast alloys. Increasing distortion was found to decrease the hardness ratio between the coating and the as-cast alloy. This is likely associated with the influence of distortion on the nanograin size in the deposition process.
For biodegradable implants, magnesium (Mg) alloys are promising materials due to several advantages, including reduced implant stress and the elimination of the need for a secondary surgery. However, deterioration in the simulated body fluid (SBF) may disintegrate the magnesium, leading to implant failure, which is the main challenge that compromises the mechanical integrity and functional life of the implant. To address this issue, research has been conducted on the development of Mg-based composites incorporating various bioactive ceramic particle reinforcements. The addition of ceramic particles as reinforcements, viz.: bioactive glass (BG), fluorapatite (FA), zinc oxide (ZnO), hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), titanium dioxide (TiO2), and magnesium oxide (MgO), represents the potential to improve corrosion resistance, biological interaction, and mechanical performance. This review provides an overview of magnesium-based biocomposites for medical applications, with a particular focus on the role of ceramic particles in controlling degradation behavior. The article discusses the evolution of biodegradable implant materials (biomaterials), different reinforcements, the corrosion mechanism of Mg-based materials, and their biocompatibility in simulated body fluid. Also, the effects of different reinforcements on mechanical characteristics, microstructure, and corrosion resistance are analyzed. The review also highlights current challenges: controlling the degradation rate and maintaining mechanical strength during healing. Finally, future research directions for advanced Mg-based biocomposites for biomedical and orthopedic applications are outlined.
The binder-jet forming technique, combined with a simplified phenolic resin impregnation process, was used to prepare high-performance silicon carbide ceramics. The carbon enhancement process was explored using a pre-mixed phenolic resin and cyclic impregnation, while cyclic pyrolysis was replaced by a baking process at 120ºC. The effects of different printing powders and impregnation cycles on the molding accuracy, density, residual silicon content, thermal conductivity, and mechanical properties of the samples were systematically investigated. The results showed that the printed density was 1.53 g/cm3, with a carbon density of 0.55 g/cm3. The phenolic resin impregnation treatment effectively filled the internal pores, further increasing the green body density to 1.71 g/cm3 and the carbon density to 0.71 g/cm3. The density of the SiC ceramics obtained by the silicone infiltration process reached 2.93 g/cm3, the thermal conductivity was 151.8 W/(m · K), and the flexural strength was 241 ± 14.08 MPa. Overall, cyclic post-impregnation of phenolic resin without the pyrolysis process can effectively enhance the density and properties of binder-injected SiC ceramics.
The fabrication route for nickel-based powder alloy samples included hot forging of porous compacts using a screw press at temperatures ranging from 950 to 1220°C, followed by vacuum annealing of the forged billets at 1210°C for 1 and 4 h. At relatively low hot forging temperatures (950–1050°C), significant residual volumetric porosity (12.5–6.5
Nanoscale Si3N4 powder facilitates densification at lower sintering temperatures, allowing sintered bodies to more readily approach theoretical density and achieve nanoscale microstructures. In this study, amorphous nanoscale Si3N4 powder was used as the starting material and consolidated via spark plasma sintering (SPS) at a heating rate of 100°C/min to investigate the effects of rapid sintering on phase ratio, microstructure, and mechanical properties. A fully densified 62
The synthesis of SiC micro- and nanofibers by chemical vapor deposition (CVD) from methyltrichlorosilane CH3SiCl3 on highly porous nickel foam substrates (matrices) was examined. The synthesis was conducted over the temperature range 1000–1200°C for 10 to 60 min. The dependence of nickel foam pore filling on synthesis temperature and time was established. The time dependence of the substrate weight gain resulting from the deposition of SiC nanofibers at constant temperature was linear. The weight gain increased exponentially with temperature at fixed holding time. The effective activation energy of the process was estimated at Ea = 107 kcal/mol (447 kJ/mol). This corresponds to the case when the decomposition of methyltrichlorosilane and the nucleation and growth of the SiC crystalline phase as nanofibers are the limiting stages in the process. According to X-ray diffraction, the fibers have a cubic β-SiC structure with lattice parameter a = = 0.4349 nm. This is also confirmed by selected-area electron diffraction patterns for nanofiber clusters taken using transmission electron microscopy. Silicon carbide nanofibers with diameters ranging from 40 to 200 nm (depending on synthesis temperature) have smooth surfaces. Among the predominant cylindrical fibers, fibers with a triangular cross-section are also observed. The two types of SiC nanofibers differ by the presence of twins in the first case and polytypes and stacking faults in the second, which is confirmed by the characteristic striped contrast in electron microphotographs and by the regular shift of reflections and streaking in electron diffraction patterns. Recommendations are formulated for the use of these composite nanostructures, namely SiC nanofibers spatially distributed in the pores of nickel foam, as catalyst carriers, fine filters for liquids and gases, and matrices for polymer-based nanofiber-reinforced composites.
