Abstract: Al₂O₃/Ti(C, N)-Ni-Ti composites were synthesized by vacuum hot press sintering. The effect of Ni and Ti on microstructure and mechanical properties were investigated. The results indicated that the composites with Ni and Ti addition were composed mainly of Al₂O₃, Ti(C, N) and Ni with no Ti. Due to its high reactivity, Ti may react with the C containing atmosphere produced by the graphite die in the hot pressing process to form TiC, or with the possible N₂ resulted from the small amount decomposition of Ti(C, N) at high temperature to form TiN, which is beneficial to the elimination of pores. Suitable addition of Ni promotes densification of the composites via liquid phase sintering, and increases relative density of the composites. Ni can also increase fracture toughness of the composites through crack deflection and crack bridging. With the addition of 5vol% of mixture of Ni and Ti (equal molar amount of Ni and Ti), the composite hot-pressed at 1500℃ has a relative density of 99.6%, Vicker’s hardness of 21 GPa, three point bending strength of 818 MPa, and fracture toughness of 8.1 MPa·m^1/2.

Key words: ceramic matrix composite, Al₂O₃-Ti(C, N), Ni, Ti, hot pressing, mechanical property