Synthesis of TiB₂-TiN Composites by Reactive Spark Plasma Sintering of BN and Ti

Abstract

Reactive spark plasma sintering technique was applied to the synthesis of TiB₂-TiN_x composites from BN and Ti powders and the simultaneous consolidation of them. The nonstoichiometry of synthesized TiN_x (x=0.6-1.0) was controlled by the change of the molar ratio of BN and Ti starting
powders and the resulting displacement reaction 2BN+(1+2/x)Ti→(TiB₂+2/xTiN_x. When x is 0.9 and below, the relative density of composites reached more than 99.6 % at a sintering temperature of 2000°C, because of the good sinterability of nonstoichiometric TiN_x. For dense composites, Young's
modulus increased with x, but hardness decreased. The composite at x=0.9 had the highest values for Young's modulus (476 GPa) and fracture toughness (3.2 MPa m^1/2)as well as good sinterability.