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V2AlC powder was prepared through self-propagating high-temperature synthesis of VO2/Mg/Al/C mixture in molten NaCl followed by leaching in dilute hydrochloric acid. The synthesized product included V2AlC, vanadium aluminides and carbides, as well as MgO and MgAl2O4. The phase composition was found to be magnesium and carbon content dependent. Optimum component ratios and acid leaching conditions were determined for the successful synthesis of V2AlC MAX phase. [ABSTRACT FROM AUTHOR]

This work is devoted to the preparation of powders of Ti2AlC and Ti3AlC2 MAX phases by self-propagating high-temperature synthesis (SHS) using the magnesium-thermal reduction from oxide feedstock. Oxide TiO2 is used as the titanium source, and magnesium is used as the reducing agent. Purification with the removal of magnesium oxide is performed in diluted hydrochloric acid at a temperature of 70°C and concentration of 1 : 3. The target product yield with the magnesium-thermal reduction is 35–40%. It is revealed that the synthesis product with the stoichiometric component ratio after chemical leaching in hydrochloric acid consists of Ti2AlC, MgAl2O4, and TiC. The formation of spinel MgAl2O4 is associated with the deficiency of the magnesium reducing agent in the charge; herewith, aluminum partially enters the reduction reaction of titanium from its oxide with the formation of Al2O3. This leads to the formation of spinel MgO ⋅ Al2O3. An increase in the content of excess magnesium in the charge from 20 to 30 wt % conditions the complete reduction of titanium from its oxide by magnesium with the formation of the Ti2AlC MAX phase and titanium carbide. A decrease of 10 wt % in the carbon content causes a decrease in the titanium carbide fraction to 4%. The product, containing Ti3AlC2 and Ti2AlC MAX phases, as well as TiC, is formed at an excess soot content from 20 to 35%, and the Ti3AlC2 weight fraction increases from 86 to 89%, respectively. These powders comprise agglomerates (87% of them are smaller than 65 μm) consisting of thin plates of MAX phases 70–100 nm in thickness. [ABSTRACT FROM AUTHOR]

The Ti–W composite (Ti/W ≈ 1 : 1) was prepared by magnesiothermic SHS followed by acid leaching and the conditions of acid leaching were optimized. Final products exhibited low contamination with byproducts, good quality, and higher resistance to dissolution in HCl. Our results may turn interesting to those engaged in production of Ti–W alloys. [ABSTRACT FROM AUTHOR]

A Ti–Zr alloy was prepared by magnesiothermic reduction from TiO2–ZrO2–Mg mixtures followed by acid leaching and the influence of leaching conditions on the quality of final product was explored. For nitric and hydrochloric acids as leaching agents, conditions for complete removal of MgO from crude TiZr–MgO combustion product had been optimized. The resistance of combustion-synthesized Ti–Zr alloy to elution with nitric acid was higher than that with hydrochloric acid. [ABSTRACT FROM AUTHOR]

Technologically viable principles have been developed for the preparation of titanium and zirconium powders via reduction of metal oxides. We have studied the effect of synthesis conditions (starting-mixture composition and relationships between reactants) on the composition, structure, and particle size of the powders. The results demonstrate that the addition of excess magnesium to the starting mixture leads to the complete reduction of the oxides and that reducing the combustion temperature of the starting mixture leads to an increase in the percentage of zirconium oxide in the final product. The titanium and zirconium powders prepared in the combustion regime with a reduction stage consist of agglomerates of particles ranging widely in size: from large (several microns) to ultrafine and nanoscale particles. The use of magnesium perchlorate as a heating additive leads to the formation of a titanium–zirconium solid solution. The composition of the powders has been determined by chemical analysis, microstructural analysis, and X-ray diffraction. [ABSTRACT FROM AUTHOR]