Enhancing the sinterability and fracture toughness of Al2O3–TiN0.3 composites

We introduce a new and effective method for improving the fracture toughness of Al2O3-based composites through the addition of a nonstoichiometric material. Al2O3–TiN0.3 composites were sintered by spark plasma sintering with different TiN0.3 content at temperatures between 1300 and 1600 °C for 10 min and a micro-region diffusion phenomenon was observed at the Al2O3–TiN0.3 interface. Ti atoms from TiN0.3 diffused into Al2O3 to occupy Al sites, which led to the formation of Al vacancies that enabled the transport of aluminum by a vacancy mechanism. The optimal densification temperature of the Al2O3–30vol% TiN0.3 composite was approximately 1400 °C. The maximum fracture toughness measured was 6.91 MPa m1/2, from the composite with 30 vol% TiN0.3 sintered at 1500 °C.