Synthesis and mechanical properties of (Ti, Mo)2AlC/Al2O3 composite by a reaction hot pressing method

A dense (Ti, Mo)2A1C/10 wt% Al2O3 in-situ composite was successfully fabricated from powder mixtures of Ti, Al, TiC and MoO3 by reactive hot pressing sintering, and the reaction path was investigated in detail. It was found that the production of the (Ti, Mo)2A1C/10 wt% Al2O3 was composed of a series of intermediate reactions: i.e., first reaction between Ti and Al forms Ti–Al intermetallics, and the thermite reaction between Al and MoO3 producing Al2O3 and Mo. Then the intermetallics and the residual Ti and Al transformed to TiAl equilibrium phase. Finally, the (Ti, Mo)2A1C/Al2O3 composite was formed by the reaction of TiAl TiC, and Mo. The Vickers hardness, flexural strength, compressive strength and fracture toughness of the composite were 4.75 GPa, 458 MPa, 971 MPa, and 6.03 MPa m1/2, which are improved by 25%, 69%, 48%, and 146%, respectively, compared to the single-phase Ti2AlC. The reinforcing mechanism was also discussed.