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 m^1/2, 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.