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Cast four-component МАХ compounds (V1–xNbx)2AlC were prepared from V2O5–Nb2O5–Al–C powder mixtures by metallothermic SHS under 5 MPa of Ar and characterized by XRD, SEM/EDS, and video filming. Target product were found to contain (V1–xNbx)2AlC compounds and Al3Nb. Synthesized materials can find their application as structural materials in high-temperature applications in aggressive media.

High-temperature synthesis of cast composite materials in the Cr–Mn–Al–C system with various ratios between the Cr2AlC MAX phase and chromium and manganese aluminides and carbides was studied. Experiments were performed in a universal 3-L reactor under argon pressure Р = 5 MPa. Mixtures of powders of chromium(III) and manganese(II, IV) oxides and calcium peroxide with aluminum (ASD-I) and carbon were used as a charge. The synthesis features and the phase composition and microstructure of the target products are significantly influenced by the reactant ratio in the charge. At the stoichiometric ratio of the components corresponding to the Cr2AlC phase, a cast composite material consisting of the Cr2AlC MAX phase, chromium carbides Cr7C3 and Cr3C2, and chromium aluminide Cr5Al8 is formed. In the course of combustion of the charge with the component ratio corresponding to the Mn2AlC phase, a cast composite material consisting of manganese carbides (Mn3AlC, Mn0.545Al0.42C0.035) and aluminide (MnAl) is formed. When these compositions are combined in an 0.75 : 0.25 ratio, the final product is a composite material consisting of a solid solution based on the Cr2AlC MAX phase, manganese carbides (Mn3AlC), and chromium aluminides (Cr2Al). When these compositions are combined in an 0.5 : 0.5 ratio, the final product is a composite material consisting of the manganese-doped Cr2AlC MAX phase and of manganese (Mn14Al86, Mn22.5Al77.5) and chromium (Cr5Al8) aluminides. The final products were characterized by X-ray diffraction and local microstructural analysis.

Using the method of self-propagating high-temperature synthesis (SHS metallurgy), cast composite materials were produced in the Cr–Ti–B system. The experiments were carried out in universal SHS reactors with an initial argon pressure of Рin = 5 MPa. Mixtures of CaCrO4, TiO2, Al, and B powders were used as batch. It was shown that by varying the mass ratio α of CaCrO4/2Al/2B and 3TiO2/4Al/6B mixtures in a batch, it is possible to significantly affect the synthesis patterns, phase composition, and microstructure of the target products. The initial mixtures are capable of burning in the range of α 0–20%. The phase separation limit occurs at α = 15%. The introduction of a highly exothermic CaO2 + Al additive into the mixture made it possible to expand the phase separation limit to α = 20%. As α increases, the amount of titanium boride in the final product increases. The resulting composite material consists of titanium-chromium boride distributed in a matrix of chromium boride. The synthesized materials were characterized by X-ray and local microstructural analysis. The structural phase states of the target products produced under various conditions were studied.

The possibility of obtaining a composite material based on titanium and chromium borides with a nickel binder by metallothermic SHS was considered. In the experiments, calcium chromates CaCrO4 and CaCr2O7 were used as the chromium-containing component of green mixtures. Thermodynamic calculations showed that the combustion temperature of the mixture based on calcium dichromate (CaCr2O7) exceeded by 200°C the combustion temperature of the mixture based on calcium chromate (CaCrO4). The use of calcium dichromate allowed us to expand the limits of combustion and phase separation of the mixture, as well as to increase the yield of the target product. XRD analysis and SEM/EDS data showed that the obtained composite material contains triple boride Ni20AlB14 as a basis and chromium and titanium borides and titanium–chromium boride, which are uniformly distributed over the material.

Explored was the extraction of target TiAl powder from SHS-produced TiAl–MgO semiproduct by treatment in acids (H2SO4, HCl,) and NH4Cl solution. Acid leaching was found to be accompanied by marked elution of target TiAl: the yield of TiAl powder was 21 and 33% in case of leaching with H2SO4 and HCl, respectively. But upon leaching with enriched NH4Cl solution at 70–80°C for 30 min, the yield of purified TiAl powder attained a value of 60%.

The possible application of self-propagating high-temperature synthesis (SHS) for preparing nanosized powders of refractory compounds is examined. The structurization of tungsten carbide and titanium carbide powders produced by SHS with a reduction stage is studied. The synthesis is based on exothermic reactions between tungsten oxide or titanium oxide, carbon, and magnesium metal. The influence of starting-mixture composition, ratio of components, and nature of adjusting additives on the particle size, morphology, and phase composition of WC and TiC powders is analyzed. Procedures are described for recovering tungsten carbide or titanium carbide from intermediate products using chemical dispersion, i.e., chemicothermal treatment of the ground cake in various solutions. As a result, impurities are removed and defect-rich intercrystalline layers are dissolved. Thus the sinter cake breaks into homogenous hexagonal WC or tetragonal TiC particles. The powder is additionally refined when the final product is treated in various solutions: the uniform shrinkage of the particles is observed because of their partial dissolution in acid and alkaline media, while the structure and properties in the central part of the substance or phase remain unchanged. The influence of the dispersion agent on the morphology and particle size of WC and TiC powders is examined. Conditions are determined for producing TiC and WC powders containing up to 80% of particles smaller than 30 nm using SHS with subsequent chemical dispersion. Based on the research, an SHS process is developed for producing ultrafine and nanosized TiC and WC powders on a commercial scale.