Fabrication of dense titanium nitride (TiN) -titanium diboride (TiB_2) Composites by Reactive Hot Pressing in Vacuum

摘要

The fabrication of dense composites in the Ti-B-N system by reactive hot pressing in vacuum of Ti and BN powders is reported. The effect of addition of a small amount of Ni (1-3wt%) on the reaction kinetics and densification of TiN-TiB_2 (40vol%) composite has been studied. Composites of ～ 99% theoretical density have been produced in vacuum (5 x 10~(-5) torr) at 1600°C under 40 MPa for 30 minutes with 1% Ni. The hardness and fracture toughness of these composites are 24.5 ± 0.97 GPa and 6.53 ± 0.27 MPa.m~(1/2) respectively. The effect of early application of pressure on reaction kinetics and densification has also been studied. The microstructural studies on samples produced at lower temperatures indicate the formation of transient liquid phase, which enhances the kinetics of the reaction and densification of the composite.