Mechanical properties and microstructure of Al2O3/TiAl in situ composites doped with Cr2O3

Al2O3/TiAl composites were successfully fabricated from powder mixtures of Ti, Al, TiO2 and Cr2O3 by a hot-press-assisted exothermic dispersion method. The effect of the Cr2O3 addition on the microstructures and mechanical properties of Al2O3/TiAl composites was characterized, and the results showed that the Rockwell hardness, flexural strength and fracture toughness of the composites increased as the Cr2O3 content increased. When the Cr2O3 content was 2.5 wt%, the flexural strength and the fracture toughness attained peak values of 925 MPa and 8.55 MPa m1/2, respectively. This improvement of mechanical properties was due to the more homogeneous and finer microstructure developed from the addition of Cr2O3 and an increase in the ratio of α2-Ti3Al to γ-TiAl matrix phases.