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.

Keywords:

• TiC–Fe composites
• Combustion synthesis
• Electric field
• Mechanism

Acknowledgements

The present work was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (grant no. 20101561-3-1) and the National Nature Science Foundation of China (grant no. 50404014). The authors would like to thank Mrs H. Wang of the Analytical and Testing Center, Sichuan University, for assistance in the experiments.