High temperature oxidation behaviour of a TiAl–Al2O3 intermetallic matrix composite

A TiAl-based intermetallic matrix composite has been produced through sintering of mechanically milled Al/TiO2 composite powder. The composite contains 42–50 vol.% of α-Al2O3 as the particulate reinforcement phase. Oxidation experiments were carried out at 800–900 °C in air up to 500 h to evaluate its oxidation and scale spallation resistance. A cast Ti–50at.%Al alloy was also tested for comparison. The composite samples showed much lower oxidation mass gain than the cast alloy under all testing conditions. Moreover, the composite samples exhibited extremely strong scale spallation resistance. Spallation could never be recorded and observed even under long-time intensive cyclic oxidation exposure. Based on the kinetic and microstructural studies, the mechanisms for the improved oxidation and spallation resistance are discussed.