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

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.