The halogen effect in the oxidation of intermetallic titanium aluminides |
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Authors: | M. Schü tze,G. SchumacherF. Dettenwanger,U. HornauerE. Richter,E. WieserW. Mö ller |
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Affiliation: | a Karl-Winnacker-Institut der DECHEMA e.V., Postfach 150104, 60061 Frankfurt/Main, Germany b Forschungszentrum Jülich, NMT, 52425 Jülich, Germany c Forschungszentrum Rossendorf, TWII, Postfach 510119, 01314 Dresden, Germany |
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Abstract: | Stoichiometric TiAl and two quasi-technical TiAl alloys were investigated in the temperature range of 800-1000°C with regard to the halogen microalloying effect on oxidation resistance. The halogens Br, Cl, F and I were introduced into the material surface by ion implantation with different doses and energies before the thermogravimetric oxidation experiments were started. The results show that a very low “homeopathic” amount of these halogens at the oxide scale/metal interface activates a mechanism of selective Al-oxidation which changes oxidation behavior from fast mixed titania/alumina kinetics to slow pure alumina kinetics. A model is described which explains this change in kinetics supported by quantitative data from thermodynamic calculations. The halogen microalloying effect offers a high potential for the improvement of oxidation resistance of TiAl alloys for technical applications. |
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Keywords: | Intermetallics Ion implantation Chlorination Interfaces Selective oxidation |
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