Microstructure and mechanical properties of hot-pressing chromium carbide/alumina nanocomposite prepared by MOCVD in fluidized bed

Nanocomposites of Cr3C2/Al2O3 were prepared by metal-organic chemical vapor deposition (MOCVD) method in a fluidized bed and sintered under hot-pressed condition at 1500 °C for1 h. The TEM microstructure showed that the Al2O3 matrix contained both intragranular and intergranular phase of Cr3C2. The hot-pressed Cr3C2/Al2O3 nanocomposites possessed better mechanical performance as regard to bending strength and fracture toughness in comparison to the monolithic Al2O3. The phenomenal change of the fracture mode from intergranular fracture of monolithic Al2O3 to transgranular fracture of nanocomposites is attributed to the enhancement of the residual stress and formation of a solid solution, eventually improving the strength of the Cr3C2/Al2O3 nanocomposite. Furthermore, it has been deciphered that the toughening mechanisms of the nanocomposites contribute to the crack deflection and the residual stress.