Oxidation behaviour of Ag-containing TiAl-based intermetallics

The effect of alloy composition on the oxidation behaviour of γ-TiAl alloys with silver additions was studied during exposure at 800 °C in air. For this purpose, a number of Ti–Al–Ag alloys with systematic variation of the chemical composition was prepared by levitation induction melting. Subsequently, the alloys were isothermally and/or discontinuously oxidised at 800 °C in air. The results showed that suitable silver additions can promote and stabilise formation of an alumina scale on γ-TiAl up to the maximum test times of 12,000 h. An oxidation map was derived which allows defining which type of surface oxide is formed on various TiAl–Ag alloy compositions. This result can be applied in further work for development of oxidation resistant coatings for γ-TiAl or/and Ti-based alloys.