Microstructure and mechanical properties of in situ synthesized Ti2AlC/Al2O3 composites

Al2O3 particle-reinforced Ti2AlC composites are successfully synthesized from the powder mixture of Ti, TiC, Al and TiO2 by in situ hot-pressing method. The effect of Al2O3 addition on the microstructure and mechanical properties of the Ti2AlC/Al2O3 composites is investigated in detail. It is found that the as-sintered products are mainly composed of Ti2AlC matrix and Al2O3 reinforcement, and the in situ formed fine Al2O3 particles tend to disperse on the matrix grain boundaries. With increasing the Al2O3 content, the Rockwell hardness, compressive and flexural strength of Ti2AlC/Al2O3 composites gradually increase. But the fracture toughness of the composites increases first then decreases with the increase in the Al2O3 and the Ti2AlC/12 wt% Al2O3 sample possesses the maximum value of 5.37 MPa m1/2, which is improved by 19.3%.

► Ti2AlC/Al2O3 composites are synthesized by in situ hot-pressing method at 1350 °C with Ti–TiC–Al–TiO2 system.
► The dispersive Al2O3 particles refine the Ti2AlC matrix on the boundary.
► Compared with monolithic Ti2AlC, the mechanical property of Ti2AlC/Al2O3 composites is obviously improved.
► The toughening and strengthening mechanism of Ti2AlC/Al2O3 composite are investigated.