Mikhail Antipov

Intermetallic materials based on titanium aluminides (TiAl and Ti₃Al) were produced from initial powder components of titanium and aluminum by the method of free SHS-compression, which combines combustion processes in the self-propagating high-temperature synthesis (SHS) mode and high-temperature shear deformation of the combustion products. To elucidate the mechanism of phase formation, the temperature and combustion velocity of the studied compositions were measured. It was established that under free SHS-compression conditions these parameters decrease with increasing fraction of free titanium and decreasing fraction of aluminum in the starting charge. It was shown that, owing to the early contact of the synthesized material with the press plunger during free SHS-compression, the phase-formation processes are completed. The regularities of the effect of the ratio of the powder reagents (titanium and aluminum) in the starting powder mixture on the phase composition, structure and mechanical properties (microhardness, elastic modulus, elastic recovery) are presented. It was found that the highest values of microhardness and elastic recovery correspond to a composition consisting of 74 wt % Ti₃Al and 26 wt % TiAl, whereas the maximum elastic modulus corresponds to a composition of 86 wt % TiAl and 14 wt % Ti₃Al.

This study investigates TNM-type titanium aluminide alloys, representing the third generation of β-stabilized γ-TiAl heat-resistant materials. The aim of this work is to study the combustion characteristics and to produce compact materials via the free SHS compaction method from initial powder reagents taken in the following ratio (wt%): 51.85Ti–43Al–4Nb–1Mo–0.15B, as well as to determine the effect of high-temperature isothermal annealing at 1000 °C on the structure and properties of the obtained materials. Using free SHS compression (self-propagating high-temperature synthesis), we synthesized compact materials from a 51.85Ti–43Al–4Nb–1Mo–0.15B (wt%) powder blend. Key combustion parameters were optimized to maximize the synthesis temperature, employing a chemical ignition system. The as-fabricated materials exhibit a layered macrostructure with wavy interfaces, aligned parallel to material flow during compression. Post-synthesis isothermal annealing at 1000 °C for 3 h promoted further phase transformations, enhancing mechanical properties including microhardness (up to 7.4 GPa), Young’s modulus (up to 200 GPa) and elastic recovery (up to 31.8%). X-ray powder diffraction, SEM, and EDS analyses confirmed solid-state diffusion as the primary mechanism for element interaction during synthesis and annealing. The developed materials show promise as PVD targets for depositing heat-resistant coatings.

Experimental studies were conducted on the high-temperature forming of materials based on TiB/TiAl(Nb, Mo)B under process conditions that combine combustion in the mode of self-propagating high-temperature synthesis (SHS) of the initial powder components and their shear deformation following the passage of the combustion wave—free SHS compression. The objects of study were composites consisting of 100% TiB–(20–40) wt % Ti (TiB layer) and TiAl(Nb, Mo)B alloy (at %: 51.85 Ti–43 Al–4 Nb–1 Mo–0.15 B), as well as two-layer composite materials with the following layer proportions, vol %: 70TiB/30TiAl(Nb, Mo)B, 50TiB/50TiAl(Nb, Mo)B, 30TiB/70TiAl(Nb, Mo)B. The degree of deformation was chosen as the criterion for formability of the composites during shear deformation. It was established that, by varying the composition of each layer in the composite and the technological parameters of free SHS compression, it is possible to regulate the degree of deformation from 0.2 to 0.55. It was shown that the technological parameters of free SHS compression (holding time, pressing pressure, deformation rate) and the initial composition affect the formability and structure of the composites. The structural features and phase composition of the composites obtained were studied. It was demonstrated that a diffusion zone forms between the ceramic and intermetallic layers as a result of chemical interaction, the size of which can be regulated within the range of 30–150 μm.

A self-propagating high-temperature synthesis (SHS) method has been used to obtain the composite materials based on TiC–NiCr–W. The influence of adding 5 and 10 wt % tungsten on the temperature and combustion rate, as well as on the phase composition and structure of the synthesized material, has been experimentally studied. It has been found that an increase in the weight content of tungsten in an initial charge blank results in a decrease in the temperature and combustion rate. It has been shown that the dependence of these parameters on the relative density of the blank is extreme; for each composition, an optimum value has been found. It has been established that the synthesized material without the introduction of tungsten consists of a strengthening TiC phase and an intermetallic Cr_1.12Ni_2.88 matrix. The introduction of tungsten into the initial charge contributes to the additional formation of the complex (Ti_0.5W_0.5)C tungsten carbide. Based on the obtained results, a flow diagram of the chemical process in the SHS mode has been presented. It has been found that a decrease in the temperature and combustion rate results in a decrease in the size of a TiC carbide grain in the synthesized material.