COMBUSTION SYNTHESIS OF COMPOSITE IN THE Ti-Al-C POWDERS MIXTURE: MODEL AND NUMERICAL SIMULATION

The work uses the basis of conventional combustion theory to propose and study a model of combustion synthesis of a composite material in a three-component powder mixture Ti-Al-C. The model takes into account the dependence of the properties on the composition and structure of the reaction system. The composition of the composite material was analyzed from the reaction initiation stage and to the product cool down. It was shown that the reaction front propagation along the specimen occurs in a stationary regime (with constant rate) for any of the specimens under study. The main synthesis products in the studied concentration range are titanium carbides, titanium aluminide and ternary phases (MAX-phases) Ti2AlC and Ti3AlC2. It was shown that the preliminary heating of the initial reaction mixture prevents the formation of MAX-phases in obtained composites and facilitates the increase in the fraction of carbide phases. Within the framework of the proposed model, the change in an initial porosity of the compact has very little effect neither on the composition evolution of the product. We have found the ranges of concentrations in the initial reaction mixture that provide the prevalence of either intermetallic (TiAl) or MAX-phase (Ti2AlC, Ti3AlC2) in the matrix. The obtained theoretical results are consistent with the experimental results.