M. Schütze, S. Friedle
MRS Proceedings 1516 (2013), 77-88, DOI: 10.1557/opl.2012.1666
Above 750-800°C oxidation becomes a serious life time issue for the new group of intermetallic light-weight high temperature alloys based on titanium aluminides (TiAl). Fast growing titanium oxide competes with protective alumina as a surface scale in the oxidation reaction by which the formation of a slow-growing protective oxide scale is prevented. The key to the development of alloys with sufficient oxidation resistance is the understanding of the thermodynamic and kinetic situation during the oxidation process. The latter is influenced by the type of alloying elements, the Al- and Ti-activities in the alloy, the oxidation temperature and the environment (e.g. dry or humid air, etc.). This paper provides a comprehensive summary of the oxidation mechanisms and the parameters influencing oxide scale formation. Besides the role of metallic alloying elements, the halogen effect will also be discussed. The paper finishes with recent results concerning the prevention of oxidation-induced room temperature embrittlement of TiAl alloys.