International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The high-temperature self-propagating synthesis (SHS) of carbides and borides in powder systems (30, 50, 70) wt.% (Fe-Ga)-(Ti-C) and (30, 50, 70) wt.% (Fe-Ga)-(Ti-B4C) was investigated at a temperature of 1200 °C in a neutral argon atmosphere. It was established that the introduction of a master alloy (Fe-55 wt.% Ga) into the initial mixture intensifies the SHS process. The appearance of a liquid phase at lower temperatures in gallium-containing systems is likely one of the main reasons for the activation of transport mechanisms for mass transfer to the chemical reaction front. Corrosion tests in a simulated seawater environment (3% NaCl solution) showed that simultaneous alloying of iron with gallium and boron significantly increases the corrosion resistance of iron-based materials. Specifically, the material containing 30 wt.% (Fe-Ga)-(Ti-B4C) demonstrated high protection (ASTM G-1, Good) in an environment close to seawater.

The contact interaction between the metal matrix composite based on Ti64 and the B4C-based composite was investigated. It is shown that the interaction process is influenced by the annealing temperature and holding time. The phase that formed independently of the contact pair is TiB. However, the thickness of the products formed at the boundary depends on the contact pair. In case of the Ti64-B4C pair the thickness is 70 μm, while for (Ti64-40 wt% TiC)-B4C it becomes 10 μm. This significant difference in the thickness is due to the presence of refractory particles (TiC) in (Ti64-40 wt% TiC)-B4C couple, because the TiC phse reduce the diffusion of Ti into the contact zone.

A novel two-stage approach for obtaining wear-resistant multifunctional powder composites based on metal powders with highmodulus Ti–TiC system fillers is proposed. The method combines high-voltage electric discharge (HVED) treatment and spark plasma sintering (SPS), offering a promising alternative to conventional techniques for producing Al–Ti–C system composites. This approach enables the development of a unified route for material synthesis using high-energy-density processing. HVED treatment prevents oxidation of metal particles, reduces contamination by tool materials, and initiates the synthesis of additional dispersed strengthening phases. For example, HVED treatment of titanium powder in a hydrocarbon liquid promotes the in situ formation of titanium carbide (TiC) particles.
The present work investigates the influence of adding Ti–TiC powder—synthesized via HVED in ethanol under reverse polarity mode with a specific energy input of 20 MJ/kg—on the structure, phase composition, and properties of Al–Ti–C metal matrix composites (MMCs). It was shown that the addition of 2 wt% of Ti–TiC powder synthesized via HVED in ethanol to aluminum powder results in an MMC with an electrical resistivity of 0.5 Ω·mm²/m and a hardness of 31 HRB. However, the heat resistance of this composite is 2.5 times lower than that of consolidated pure aluminum powder. Increasing the Ti–TiC content to 10 wt% leads to the formation of a wear-resistant Al–Ti–C composite, whose structure includes Al, Ti, TiC, the intermetallic compound Al₃ Ti, MAX phases Ti₂ AlC and Ti₃ AlC₂ , and free carbon. For the MMC sample with the addition of 10% Ti–TiC, the mass gain per cycle during the heat resistance test is 0.23%/cycle, whereas for samples made from consolidated Al powder it is 0.18%/cycle, indicating that their heat resistance is approximately the same. The wear resistance of this composite is more than three times higher than that of the consolidated base aluminum powder, with wear rates of 0.003 g/km and 0.010 g/km, respectively. This material also demonstrates a hardness of 43 HRB and relatively low electrical resistivity at the level of 0.3 Ω·mm²/m.

High-voltage electrical discharge (HVED) treatment of powder mixtures is a modern, efficient, and economically advantageous method for both particle size reduction and modification of the material’s phase composition. The primary mechanisms of particle destruction within the discharge zone include shock waves, microcavitation, ablation, collisions with chamber components, and mutual abrasion between particles.
The application of machine learning methods to model HVED processes for titanium—a promising material for composite applications— enables more accurate predictions and optimization of the technological workflow.
The data used for modeling were obtained between 2013 and 2021 and include results from the treatment of the initial titanium powder (with an average diameter of d₀ = 60 μm) in ethanol. This setup enabled the formation of a volume-distributed multi-spark discharge (VMD) within the ethanol–powder dispersed system. The dataset includes information on the number of treatment pulses, discharge gap, pressure in the discharge channels, pressure on the chamber walls, and the amount of titanium carbide formed during the treatment process.
It was shown that the concentration of TiC gradually rises with the increase of specific treatment energy, regardless of the interelectrode gap. Specifically, at a specific energy (Ws) of 5 to 15 MJ/kg, the amount of titanium carbide reaches 10%; at 15 to 30 MJ/kg, it increases to 20%; and at energy levels above 30 MJ/kg, the TiC content reaches 30%.
Keywords: Ethanol, Titanium, Titanium Carbide, High-Voltage Electrical Discharge, Volume-Distributed Multispark Discharge, Electric Discharge Dispersion, Plasma Technologies, Machine Learning, Logistic Regression, Random Forest

The phase and structure formation of aluminum-matrix composite materials reinforced with titanium carbide during their synthesis and consolidation using the forging were investigated. The influence of copper additives on the structure formation, density, porosity, and hardness of aluminum-matrix composites was determined. The research results revealed the presence of Al+Cu+TiC phases in copperalloyed samples. Studies of density and porosity showed that the samples without copper additives were maximally densified after hot stamping and had minimal porosity, unlike the copper-alloyed composites.

The electrochemical corrosion properties in a 3% NaCl solution of the titanium-based multicomponent composite of the 65TiH2–30FeSiMn–B4C system were investigated. The kinetics and the mechanism of anode dissolution of metals and oxidation of specimens have been studied by using polarization curves, chemical and x-ray phase analyses. It was found a decrease in the titanium carbide peaks on the X-Ray defractions also the titanium silicon carbide almost disappears after immersing the sample in a 3% NaCl solution. Formation of silicon and boride phases of titanium in the synthesis process leads to an increase in corrosion resistance due to the inhibition of the velocities of both the anode and cathode processes.

The work shows that there is no significant change in the phase composition of composites with a change in the synthesis temperature, so we can use pre-synthesized heats at a temperature of 950 oC to obtain hot-stamped aluminum-based composites. The best characteristics of the synthesized titanium carbide were obtained for the composition 45Al-11C-44Ti (%, wt.). The lattice period of titanium carbide for this sample is 0.4324, and the particle size of titanium carbide formed after sintering is 0.8-1.5 μm. The influence of the component composition of the initial charge on the features of the structure and the phase composition of the thermally synthesized heat of the Al-C-Ti system was established.

The high specific strength of Ti-based alloys and composites makes them highly requested materials in various structural applications. However, reinforcement of the alloys with hard particles generally lowers the values of toughness and plasticity of material. A satisfactory combination of plastic and strength can be achieved by formation of layered structures comprising of two and more layers of different materials with different chemical compositions within individual layers. The multi-layer materials allow controlling the mechanical properties of the individual layers by changing microstructure and chemical composition within each layer specifically. In the present study, a cost-efficient process of fabrication of Ti-based multi-layer composites using blended elemental powder metallurgy (BEPM) and TiH2 powder is proposed. Two and three-layered composites based on titanium or Ti-6Al-4V alloy and their metal-matrix composites (MMC) with TiC and TiB were fabricated. Multi-layered samples reinforced by TiC were successfully sintered due to very close shrinkage of adjacent layers. Shrinkage values of layers reinforced by TiB were lower than those for the Ti-alloy, which led to delamination of layered structures, distortion of shape, and cracking. We can control shrinkage in individual layers by means of optimizing the powder size, that allows to obtain multi-layer titanium matrix composites reinforced by TiB with well-balanced mechanical properties.

The feachures of structure and phase formation of TiC hardened Fe-based alloy at in-situ thermal synthesis from mixtures of TiH₂, Fe, graphite and Ni powders had been investigated. It was shown that after synthesis at 1200 ⁰С the structure of the alloy is a skeleton of titanium carbide grains of various shapes and sizes from 1 to 20 µm cemented with Fe-based binding substance mostly located around the titanium carbide grains. The phase composition of the obtained alloy includes mainly phases of titanium carbide and α-Fe. In the case of using the initial mixture with the Ni in the composition of the alloy along with the titanium carbide solid solution of Ni in alpha-iron and Ni-based compounds were identified. When Ni is used instead of Fe in initial powder mixture it leads to a noticeable refinement of the alloy grain structure: the size of the carbide grains is generally not more than 5-7 microns. With the decrease in Ni content in the mixture and respectively increase of iron content at the same Ti and graphite content, the particle size increases markedly and approaches with 5 % of Ni to the particle size of the alloy obtained from the mixture containing no Ni.

The effect of filler concentration of the powder mixture (Ti-TiC-C), synthesized by high-voltage electric discharge (HVED), on the thermal and mechanical properties of epoxy composites, was studied. Basing on the value analysis of destructive stresses in bending (σ), Young’s modulus (E), resilience (W) and heat resistant by Martens (T), a range of powder mixture (Ti-TiC-C) concentration, which allows to increase thermophysical and mechanical properties of epoxy composites for manufacturing equipment in conditions of alternating loads was set.