The improvement of high temperature oxidation of Ti–50Al by sputtering Al film and subsequent interdiffusion treatment

The high temperature oxidation resistance of Ti–50Al can be improved by sputtering an Al film and subsequent interdiffusion treatment at 600 °C for 24 h in high vacuum. In these conditions, a TiAl3 layer is formed on the surface, which exhibits good adhesion with Ti–50Al substrate and provides high oxidation resistance. Cyclic and isothermal oxidation tests show that the Ti–50Al with 3–5 μm Al film can dramatically reduce the oxidation at 900 °C in air, at which the parabolic oxidation rate constant Kp of specimen with 5 μm Al film is only about 1/15,000 of that of bare Ti–50Al. XRD and SEM results indicate that the TiAl3 layer can promote the formation of a protective Al2O3 scale on the surface as well as react with γ-TiAl to form TiAl2 during the oxidation. Simultaneously, layers of Al2O3/TiAl2/Al-enriched γ-TiAl/Ti–50Al are also formed on specimens. The TiAl2 layer thickness will decrease gradually with increasing the oxidation time. After oxidation at 900 °C for 300 h, there is a clearly discontinuous thin layer of Ti37Al53O10 compound observed in between Al2O3 and TiAl2.