Reaction mechanisms of the TiC/Fe composite fabricated by exothermic dispersion from Fe-Ti-C element system

In this paper, the iron matrix composite TiC/Fe was fabricated by an in-situ process called exothermic dispersive synthesis from a powder blend of pure elements Fe, Ti and C. The microstructure of the resulting composite was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). Only TiC phase was found to form during the heating process. Differential scanning calorimetry (DSC) analysis reveals that the reaction between C and Ti occurs through one step and its activation energy is 2586.5. kJ/mol. Moreover, with the increase of the heating rate, the reaction peak shifts to the higher temperature. The whole reaction consists of three distinct stages: at the start, the reaction rate is very slow, and then it increases rapidly, finally it becomes slow again toward the completion. During the heating process, C diffused into the iron matrix and the content of C in the iron can exceed 2.11%, leading to the formation of both eutectic and eutectoid structure in the final composite. © 2013.Heguo Zhu, Kang Dong, Huan Wang, Jiewen Huang, Jianliang Li, Zonghan Xi