Effect of zirconia and iron on the mechanical properties of Al2O3/TiC composites processed using combined self-propagating synthesis and direct consolidation technique

Self-propagating high temperature synthesis combined with direct consolidation technique was used to synthesize high density Al2O3/TiC composites from mixture of TiO2, Al and graphite powders. The effect of controlled amount of zirconia and iron addition on the density, microstructure and the mechanical properties of the composites was investigated. The results revealed that, addition of either 1.0 mol zirconia or 5.0 wt% of iron metal powder led to a significant decrease in the sample porosity from 7.0 to less than 1.0 vol% together with a remarkable enhancement in the microhardness from 6.0 to 11.0 and 12.0 GPa with 1.0 mol zirconia and 5.0 wt% iron additions, respectively. Moreover, the fracture toughness increased from 3.5 to 6.0 and 7.0 MPa m1/2 with 1.0 mol zirconia and 15 wt% iron additions, respectively. However, addition of 1.0 mol zirconia with 5.0 wt% iron powder led to a composite with higher porosity and reduced mechanical properties.