Influence of aluminium content on the oxidation behavior of binary Ti-Al alloys

The isothermal oxidation, at 800 degrees C and 900 degrees C in air, of five kinds of Ti-Al binary alloy with aluminium content from 33.3 at% Al to 52 at% Al has been investigated. X-ray diffraction and scanning electron microscopy have been used to analyze the oxidation products, and the surface and cross-section microstructures of the oxide scale. It is shown that the oxide scale of binary Ti-Al alloys consists typically of a series of thin layers rather than a thick continuous and dense protective layer of AI(2)O(3); The aluminium content has a strong influence on the morphology and distribution of Al2O3 in the oxdation scale, and the isothermal oxidation rate. The oxidation rates of binary Ti-Al alloys (33.3Al, 46Al, 48Al, 50Al and 52Al) decrease with the increase of Al content at 800 degrees C, and this is also true for oxidation at 900 degrees C except the 52Al which shows heavier weight gain than do the 46A1, 48Al and 50Al alloys after 100 h of oxidation. The mechanism of the influence of Al content on the oxidation behavior of binary T1-Al alloy is discussed.