Reactive hot pressing of titanium nitride-titanium diboride composites at moderate pressures and temperatures

Abstract

Dense composites in the Ti-B-N system have been produced by reactive hot pressing of titanium and BN powders. The effect of the addition of a small amount of nickel (1-3 wt%) on the reaction kinetics and densification of TiN-TiB₂ (40 vol%) composite has been studied. Composites of ~99% of theoretical density have been produced at 1600°C under 40 MPa for 30 min with 1% nickel. The hardness and fracture toughness of these composites are 24.5 ± 0.97 GPa and 6.53 ± 0.27 MPa·m½, respectively. The microstructural studies on samples produced at lower temperatures indicate the formation of a transient liquid phase, which enhances the kinetics of the reaction and densification of the composite.