Effect of Al_2O_3 on the microstructure and mechanical properties of Ti_3AlC_2/Al_2O_3 in situ composites synthesized by reactive hot pressing

摘要

Ti_3AlC_2/Al_2O_3 in situ composites with different Al_2O_3 contents were successfully synthesized from the powder mixture of Ti, TiC, Al and TiO_2 by a reactive hot-pressing method at 1350 °C. The effect of Al_2O_3 on the microstructure and mechanical properties of the composites was investigated in detail. The results indicate that the as-fabricated products mainly consist of Ti_3AlC_2, Al_2O_3 and a small amount of TiC. With increasing the Al_2O_3 content, the flexural strength of Ti_3AlC_2/Al_2O_3 composites increase gradually, the fracture toughness reaches the peak value of 8.21 MPa m~(1/2) as the Al_2O_3 content increasing to 9 wt%, the hardness attains the maximum value of 10.16 GPa for 12 wt% Al_2O_3. The strengthening mechanism of the composites was also discussed.