Abstract
The oxidation behavior of the intermetallic compounds TiAl containing 34-38 mass%Al has been investigated in a temperature range between 1073 and 1223 K under an atmospheric pressure. The oxidation products have been examined by X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. They are composed of four layers, i.e., TiO2, Al2O3, TiO2+Al2O3 and Ti3Al from the outer side.
The mass gains during the oxidation obey the parabolic law, which increase rapidly at temperatures above 1073 K. An increase of Al content in TiAl does not change the oxidation resistance but decreases the quantity of spollation of the oxide scales during the cooling. As the oxidation rate of TiAl is lower than that of pure Ti, the existence of the Al2O3 layer have improved the oxidation resistance of TiAl. This Al2O3 layer, however, is not enough dense so as to prevent the oxidation above 1073 K.
