Modeling the kinetics of non-isothermal heterogeneous interaction during combustion synthesis of advanced micro- and nanocrystalline materials

Abstract

The combustion synthesis (CS), or self-propagating high-temperature synthesis (SHS) is a cost and energy efficient route for producing a wide range of refractory compounds (carbides, silicides, intermetallics) and advanced micro- and nanocrystalline materials. However, despite 40 years of extensive studies and industrial applications, intricate phase formation mechanisms that operate during CS are still not well understood. This hinders the development of novel materials and SHS-based technologies. An answer to the most urgent question in this area, viz. "why in CS the interaction accomplishes in a short time, ~0.1-1 s, while the traditional furnace synthesis of the same material takes several hours for the same starting composition, particle size and final temperature," can be found only through mathematical modeling. In this work, the results of mathematical modeling of the interaction kinetics in condensed systems in non-isothermal conditions typical of CS are reported. Calculations were performed using the experimental data on SHS and diffusion parameters for the product phases on the example of TiC and NiAl. The maps of phase formation mechanisms that operate during CS are constructed. The uncommon, non-equilibrium interaction pathways, which were observed experimentally and debated in literature, are confirmed theoretically ex contrario.