Microstructure and mechanical properties of Ti3(Al,Ga)C2/Al2O3 composites prepared by in situ reactive hot pressing

Abstract

In this study, Ti3(Al,Ga)C2/Al2O3 composites were successfully synthesized by in situ hot pressing at 1350 °C for 2 h using Ti, Al, TiC, and Ga2O3 as raw materials. X-ray diffraction and scanning electron microscopy were used for characterizing the phase identities and microstructures of the sintered composites. The dependence of the Vickers hardness and flexural strength on the Al2O3 content was found to be in single-peak type. Ti3(Al0.6,Ga0.4)C2/10.3vol%Al2O3 composite exhibited significantly improved mechanical properties. Vickers hardness and flexural strength of the composite reached 6.58 GPa and 527.11 MPa, which were 40% and 74% higher than those of Ti3AlC2, respectively. Formation of solid solution and incorporation of second phase of Al2O3 resulted in the opposite influence on the fracture toughness. Finally, the hardening and strengthening mechanisms were discussed in detail.