Effect of TiB2/TiC ratio on the microstructure and mechanical properties of high volume fractions of TiB2/TiC reinforced Fe matrix composite

Dense high volume fractions of different molar TiB2/TiC ratios reinforced Fe matrix composite were successfully fabricated through the SHS reaction assisted with pressure. The reaction mechanisms for three systems were dissolution–precipitation. The TiB2 morphology changed from plate-like to clubbed and further to cubic with decreasing TiB2/TiC ratios from 2:1 to 1:2. The composites with 2:1 and 1:1 ratios of TiB2/TiC have a similar highest Vickers hardness and flexural strength while the composite with 1:1 ratio of TiB2/TiC has the best fracture toughness. The improvement of the fracture toughness was attributed to the reduction of thermal stress and the modification of TiB2 morphology. The optimal ratio of TiB2/TiC was recommended to be 1:1.