Reactive hot pressing and mechanical properties of TiAl3/Ti3AlC2/Al2O3 in situ composite

Dense TiAl3/Ti3AlC2/Al2O3 composite was synthesized from Al, TiO2 and TiC powder mixture at 1250 °C and 50 MPa for 10 min using an in situ reaction/hot-pressing method. The reaction kinetic, microstructure, mechanical properties and toughening mechanism of the fabricated composite were investigated. TiO was found to be the transitional phase, and the reaction path for the Al/TiO2/TiC system was proposed. The composite achieved Vickers Hardness, three-point bending strength and fracture toughness of ∼8.4 GPa, ∼658.9 MPa and ∼7.9 MPa/m1/2, respectively. Analysis of microstructure/crack propagation paths interaction revealed that crack deflection, crack bridging, and pull-out of the Ti3AlC2 particles were the main mechanism responsible for the toughening. The compressive strength of the in situ composite was much higher than that of as-cast TiAl3 and could be maintained even at 1000 °C. This was mainly attributed to the cooperative strengthening introduced by Ti3AlC2 and Al2O3.