AlN–TiB2 composites fabricated by spark plasma sintering

Dense AlN–TiB2 composites doped with Y2O3 were prepared by spark plasma sintering. X-ray diffraction and transmission electron microscopy analyses show that no TiN was formed in the sintering process while BN was formed. The maximum values of hardness and toughness were up to 15.0 GPa and 5.6 MPa m1/2, respectively. The improved toughness is considered to be mainly associated with the crack deflection due to a weak interface between AlN and TiB2 as well as a high resistance to crack propagation in the AlN matrix region due to a large residual compressive stress from thermal expansion mismatch between AlN and TiB2.