Toughening mechanism of alumina-matrix ceramic composites with the addition of AlTiC master alloys and ZrO2

Titanium carbide and aluminium are introduced in alumina matrix in the form of AlTiC, which is a kind of master alloy. Alumina-matrix ceramic composites are prepared by using transient liquid phase and hot-press sintering. Significant improvements in mechanical properties have been attained due to the good toughening effect of AlTiC master alloys and ZrO2. The microstructures and toughening mechanisms of the fabricated alumina-matrix ceramic materials are analysed using a scanning electron microscope, a transmission electron microscopy and an electron probe microanalysis, respectively. Results show that the microstructures of “intracrystalline shape” and “intercrystalline shape” are formed and “sublattice” exists in the composites, which may extend crack path and restrain intracrystalline failure, thus improving the fracture toughness of the composites.