Microstructure and Mechanical Properties of Al_2O_3/Ni Cermet

Ni-coated Al_2O_3 powders with different Ni content were prepared by the coating technique. The powders were sintered by hot-pressing, and Al_2O_3/Ni cermet obtained. Results show that the densification is enhanced with the increase of temperature, and when temperature is more than 1400℃, the densification is decreased with the increase of Ni content. Ni particles introduced in Al_2O_3 ceramic matrix can reduce grain sizes, enhance strength and toughness. Com- pared with single phase Al_2O_3 material, Al_2O_3/4vol% Ni cermet has flexural strength of 19% and fracture toughness of 35% enhanced. SEM photos of fracture surface show that the fracture model of the cermet changes from intergranular fracture to transgranular fracture with the increase of Ni content.