抄録
TiB2-C preforms formed with different composition and processing parameters were reactively infiltrated by Si melts at 1450 degree C to fabricate TiB2-SiC-Si composites. Phase constituent and microstructure of these composites were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The resulting composites are generally composed of TiB2 and reaction-formed beta-SiC major phases, together with a quantity of residual Si. Unreacted carbon is detected in the samples with a starting composition of 2TiB2+1C formed at higher pressure and in all of the ones at the composition of 1TiB2+1C. The distribution of these phases is fairly homogenous in microstructure. TiB2-SiC-Si composites show good mechanical properties, with representative values of 19.9 GPa in hardness, 395 GPa in elastic modulus, 3.5 MPa1/2 in fracture toughness and 604 MPa in bending strength. The primary toughening and strengthening mechanism is attributed to the crack deflection of TiB2 particles.
