High Purity and High Density Ti3SiC2/Al2O3 Composites Were Prepared at High Temperature

Abstract In this study, Ti3SiC2/Al2O3 composites were prepared via in-situ hot pressing sintering at 1550 °C. Al used as a sintering aid reduced the production of TiC impurity phase and stabilized the crystal lattice of Ti3SiC2 to inhibit its decomposiition at high temperature. This is because Al replaced some of the Si atoms to form Ti3(Si1 − xAlx)C2, which showed a crystal structure similar to that of Ti3SiC2. The addition of Al is a prerequisite for the formation of high density Ti3SiC2/Al2O3 composites at high temperature. Laminar Ti3SiC2 grains and granular Al2O3 grains were densely packed and tightly bonded, furthermore, unique mosaic structure of Ti3SiC2-Al2O3 created at high temperatures improve the mechanical properties such as hardness, bending strength and fracture toughness of Ti3SiC2/Al2O3 composites, with the highest reaching 16.97 GPa, 553.38 MPa and 9.63 MPa·m1/2, respectively. The mechanism responsible for improved mechanical properties for Ti3SiC2/Al2O3 composites were the synergistic action of grain pullout, microcrack deflection, and extend the crack growth from two different kinds of grains.