Microstructure and properties of hot-pressed (Hf, Ti) C

The effect of composition, sintering temperature and time on the properties of (Hf, Ti) C hardmetals are investigated. Sintered samples were hot pressed from HfC0.7 and TiC0.9 carbide powder using powder metallurgical techniques. Ni was used as a binder in selected samples and C black was added to compensate for sub-stoichiometry and to aid in the reduction of oxides formed during milling. Hardness, fracture toughness and density decrease with increasing amounts of C in the starting powder. No change in hardness or fracture toughness (within experimental error) is observed with increasing Ni concentration from 0 to 8 wt%. The best combination of hardness and toughness attained in this investigated is 23 GPa and 10 MPam1/2, respectively, in a sample consisting of 82.7 wt% HfC + 17.3 wt% TiC + 4 wt% Ni.