Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 37: Topical Session High Temperature Materials IV

MM 37.5: Vortrag

Donnerstag, 26. März 2009, 11:30–11:45, IFW A

Investigations of γ-TiAl alloys for industrial application — •Gregor Hullin and Mathias Göken — Institute General Materials Properties, University Erlangen-Nürnberg, Erlangen, Germany

The aim of this work is to improve γ -TiAl alloys for application in automotive engines like turbo chargers or valves. Due to the lower density of TiAl alloys of about 4 g/cm3 the acceleration and the responding characteristics of a turbo charger can be improved. Furthermore the amount of harmful substances in the exhaust gases can be reduced by the elevation of the exhaust temperature. These two facts pose a challenge to find a capable TiAl alloy which has the potential to replace already existing Ni-based superalloys as turbine material. The turbine wheels are fabricated by a newly developed precision casting method. Due to this process high cooling rates can be achieved and therefore a very fine fully lamellar microstructure is produced. This structure in comparison to duplex microstructures has best balance of mechanical properties and is therefore appropriate for the use in turbo chargers. The mechanical properties are determined against casting parameters by doing creep experiments, compression and tensile tests. TiAl alloys remain limited in practical use to about 800°C because of the fast growing non-protective intermixed oxide scale. To make these alloys suitable at elevated temperatures a method to improve oxidation resistance is also under study.