(Ti,Cr)C synthesized in situ by spark plasma sintering of TiC/Cr3C2 powder mixtures

(Ti,Cr)C was synthesized and consolidated in situ by spark plasma sintering (SPS) of two TiC/Cr3C2 powder mixtures of distinctly different particle sizes. SPS of both mixtures successfully produced single-phase (Ti,Cr)C in two minutes at 1800°C. It was found that the nanoscale mixture consists of fine and uniformly dispersed TiC/Cr3C2 particles while the micron-scale mixture consists of particles aggregated and unevenly distributed. The (Ti,Cr)C consolidated using nano-scale mixture retained an equilibrium grain structure linear grain boundaries thanks to the fine and uniform elemental distribution. On the contrary, the grain boundaries of (Ti,Cr)C consolidated using micron-scale mixture were heavily serrated with Cr-richer composition. It is believed that Cr3C2 melts and forms networks where it starts to react with TiC to form solid solution leaving serrations along the grain boundaries because of its non-uniform distribution. The higher fracture toughness of (Ti,Cr)C consolidated from nano-scale mixture may be attributed to its uniform microstructure.