Investigation of the Fluorine Microalloying Effect in the Oxidation of TiAl at 900℃ in Air

摘要

The oxidation resistance of TiAl at elevated temperatures > 750℃ 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 required fluorine amounts for the establishing of the microalloying effect are determined in the case of ion implantation and treatment with HF. The fluorine maximum is found to be at the oxide/metal interface, which supports the theoretical explanation of the fluorine microalloying effect. The oxidation behaviour up to 1000h/900℃/air shows a slow alumina growth kinetics. This offers the possibility for a technical application of the fluorine microalloying effect to improve the oxidation resistance of TiAl-alloys at temperatures >750℃.