Synthesis of the Ti2AlC MAX Phase with a Reduction Step via Combustion of a TiO2 + Mg + Al + C Mixture

Abstract

Technologically viable principles have been developed for the preparation of the MAX phase Ti₂AlC by self-propagating high-temperature synthesis (SHS) with a reduction step, using titanium dioxide. We have studied the influence of synthesis conditions (starting-mixture composition and ratio of reactants) on the composition, structure, and particle size of Ti₂AlC powders. The results demonstrate that an excess of magnesium in the starting mixture leads to a decrease in the percentage of MgAl₂O₄ (spinel), and carbon deficiency in the starting mixture reduces the percentage of titanium carbide in the final product. The Ti₂AlC powders prepared by SHS consist of agglomerates of layered particles differing in size: from coarse (several microns) to ultrafine and nanometer-sized particles. The composition of the powders was confirmed by chemical analysis, microstructural examination, and X-ray diffraction.