Improvement of the Oxidation Resistance of new Light Metal Alloys using Liquid Phase and Gas Phase Treatment

The γ-TiAl based alloys are one of the most advanced intermetallics, and due to their excellent specific strength at high temperatures, they have succesfully demonstrated their potential for aerospace and automotive applications, such as turbine blades, exhaust valves and turbocharger rotors. The specific weight of components manufactured from the γ-TiAl alloys is reduced by a factor of 2 compared to the presently used Ni-based superalloys. Hence a distinct reduction of fuel consumption and a lower mechanical wear are expected. However, there is an insufficient oxidation resistance at temperatures above 800°C. One method used to improve the γ-TiAl oxidation behaviour is the halogen effect which occurs at temperatures above 800°C. As result of the halogen effect an alumina scale is formed showing a slow growing kinetics. The halogens (fluorine, chlorine) are deposited within the metal surface using ion implantation. The aim of this project is the development of cost-effective methods of halogenizing - especially with regard to the complex geometies of products manufactured from TiAl-alloys.