Mechanism of combustion synthesis of TiC–Fe composites under the action of an electric field

Abstract

The combustion synthesis process of the 55 wt-%(Ti+C)–45 wt-%Fe system was studied under two different fields. The simplex thermal field was provided by differential scanning calorimeter and high temperature X-ray diffraction equipment, while the electric field was generated by a Gleeble thermal simulation instrument. With the aid of an electric field, the system is able to be ignited at 394°C, which is much lower than the ignition temperature of above 920°C required if only a simplex thermal field is used. This is because solid diffusion among reactant atoms could be accelerated at a lower temperature by the coeffect of an electric field and the self-generated thermal field. Microstructure study revealed the formation of instantaneous liquid phase in microzones during combustion. A four step model describing the mechanism for the combustion synthesis of TiC–Fe composites under an electric field is also proposed.