Application of ion beam analysis for the control of the improvement of the oxidation resistance of TiAl at 900 °C in air by fluorine ion implantation and HF-treatment

The oxidation resistance of TiAl at elevated temperatures >750 °C can be improved by the addition of small amounts of fluorine. The fluorine is applied in two ways: ion implantation and wetting with diluted HF. Using non-destructive Ion Beam Analysis the fluorine depth concentration profiles in the near surface region are determined before and after oxidation. The fluorine maximum is found to be at the metal/oxide interface, which supports the theoretical explanation of the fluorine microalloying effect. The time dependent behaviour of the fluorine content is characterized by a fast decrease of the fluorine concentration during the first hours of oxidation followed by a moderate decrease. The results offer the possibility for a technical application of the fluorine microalloying effect to improve the oxidation resistance of TiAl-alloys at temperatures >750 °C.