Effects of residual stress and intragranular particles on mechanical properties of hot-pressed Al2O3/SiC ceramic composites

Al₂O₃/SiC ceramic composites with different SiC contents have been prepared by powder metallurgy at 1600 °C for 120 min at 30 MPa pressure. The effect of second phase particles on the microstructure and mechanical properties of composites have been studied. The results show that SiC particle has a significant impact on the matrix subjected to residual stress, and on the microstructure of the composites as well. The average grain size of alumina matrix decreases as the SiC particle content increases. Simultaneously, it has been found that the mechanical properties of the material are significantly enhanced in comparison with monolithic Al₂O₃. The highest strength and toughness are obtained when the SiC content is 15 vol%, and the values are 1237 MPa and 5.68 MPa m^1/2, respectively. The mechanisms of strengthening and toughening have been discussed.