Inhibition of high‐temperature embrittlement in titanium aluminides by designed pack cementation coatings and the halogen effect


Bild Forschungsprojekt

Hochtemperaturofen in Betrieb

Period: 2013-02-01 to 2015-07-31
Funder: Federal Ministry for Economics and Technology (BMWI, Germany) via AiF
Project Manager: Julia Greff
Research Group: High Temperature Materials

With less than half the density of nickel-base alloys and good mechanical properties, intermetallic titanium aluminide alloys represent an important class of high temperature structural materials and offer a wide potential for industrial applications, e.g. for turbine blades or turbolader wheels. One of the drawbacks of these alloys is their insufficient oxidation resistance and embrittlement at higher temperatures (> 700°C). In order to effectively replace the heavier nickel-base alloys currently in use, the surface of titanium aluminide alloys has to be modified to overcome this drawback.

To address this problem, a combination of Al enrichment plus additional fluorine treatment is used to protect the alloy against the rapid diffusion of oxygen at high temperatures which leads to structural damage of the material. Indeed, Al-rich coatings plus fluorine are expected to promote the formation of a protective alumina layer at high temperatures which not only protects the alloy from oxidation, but also impedes embrittlement at high temperatures.

To accomplish this goal advanced coatings will be produced by means of a metal-organic chemical vapor deposition process at DFI. Additionally fluorine will be implanted at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) by plasma-immersion-ion-implantation (PI3). The coating effect on the oxidation behavior of the technical titanium aluminide alloys will then be examined under isothermal and thermocyclic conditions (800-1000°C) in air, and the mechanical properties of coated and uncoated samples after atmospheric exposure will be compared using 4-point bend tests to investigate the room temperature strength and ductility after exposure.


Das IGF-Vorhaben Nr. 17668 der Forschungsvereinigung DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main wurde über die AiF im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung (IGF) vom Bundesministerium für Wirtschaft und Energie aufgrund eines Beschlusses des Deutschen Bundestages gefördert.

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