Characterization and formation mechanisms of the TiC-Fe cermet layer in Ti-TiC-Fe composites

A Ti-TiC-Fe cermet composite with a core-shell structure was fabricated by an in situ reaction at high temperature. The TiC-Fe cermet layer was formed at the interface between Ti and the gray cast iron (GCI). The XRD results indicate that the TiC-Fe cermet layer is composed mainly of α-Fe, Ti, and TiC. The statistical results of the electron backscattering diffraction (EBSD) indicate that the grain sizes are between 2 and 17 μm with the mean value of about 4 μm. The scanning electron microscope (SEM) analysis results demonstrated that the TiC-Fe cermet layer enwrapped the metallic Ti wire. The size of the TiC particles in the TiC-Fe cermet layer diminished gradually, and the tridimensional morphology varied from dense block to cubes or near-spheroids with the distance from interface of Ti/cermet layer to the interface of cermet layer/GCI. Accordingly, the nano-indentation results showed that the hardness of the TiC-Fe cermet layer decreased gradually with distance from interface of Ti/cermet layer to the interface of cermet layer/GCI, and that the highest hardness value of the TiC-Fe cermet layer is nearly 28.0 GPa. The high hardness and volume fraction of TiC-Fe cermet layer will obviously enhance the wear resistance of composites.