Microstructure and mechanical properties of in situ TiAl/Ti2AlC composites prepared by reactive hot pressing

TiAl/Ti2AlC composites with a broad range of composition are successfully fabricated utilizing in-situ reactive hot pressing method with Ti, Al and TiC powders as starting materials. Effects of the Ti2AlC contents from 0 wt% to 75 wt% on the microstructure and mechanical properties of the composites were investigated. The phase transformation at different temperature was characterized by XRD, and the microstructures were measured by SEM equipped with EDS. The result shows that Ti reacted with Al to form TiAl intermetallics below 900 °C; and above 900 °C, TiAl reacted with TiC to produce dense composites. The products sintered at 1300 °C have obvious lamellar structure. With the increasing of the Ti2AlC content, the density and hardness of the TiAl/Ti2AlC composites increase gradually, the fracture toughness and bending strength reach the peak value of 7.78 MPa m1/2 and 486 MPa at 15 wt%Ti2AlC content. The strengthening mechanism of the composites was also discussed.