Mechanical properties of (Ti,V)C-Ni composite prepared using ultrafine solid-solution (Ti,V)C phase

(Ti,V)C-Ni composite was sintered using ultrafine (Ti,V)C solid-solution powders prepared by mechanically alloying a Ti-V alloy/graphite powder mixture. The (Ti,V)C-Ni powders were sintered to full density at 1400 °C, which is significantly lower than that required for the conventional liquid-phase sintering of TiC-Ni or Ti(CN)-Ni powders. The examination of linear shrinkage curve during sintering revealed that the consolidation of the (Ti,V)C-Ni composite proceeds in three distinct steps. Firstly, it shrinks by the solid-state sintering. Afterwards, it expands by CO gas evolution. Finally, Ni melt penetrates into the pores between carbide particles during the liquid-phase sintering. The fracture toughness values of the (Ti,V)C-Ni composite were notably higher than those of TiC-Ni or even Ti(CN)-WC-Ni composites. The improved fracture toughness of the (Ti,V)C-Ni composites is believed to originate from the solid-solution effect of TiC and VC in addition to the lack of core/rim structure, which is common in Ti(CN)-WC-Ni composite.