In situ reacted TiB2-reinforced alumina

In situ formation of TiB2 in Al2O3 matrix through the reaction of TiO2, boron and carbon has been studied. In hot-pressed samples, in addition to TiB2, TiC and Al2TiO5 were also found to be dispersed phases in Al2O3 matrix. However, in the case of pressureless-sintered samples, pure Al2O3/TiB2 composite with > 99% relative density can be obtained through a preheating step held at 1300°C for longer than 30 min and then sintering at a temperature above 1500°C. Pressureless-sintered composite containing 20vol% TiB2 gives a flexural strength of 580 MPa and a fracture toughness of 7.2 MPa m1/2.