Isothermal Oxidation Behavior of Ti50Al Alloy wit

Authors: Y Wu Y Umakoshi X W Li T Narita

Publish Date: 2006/11/09

Volume: 66, Issue: 5-6, Pages: 321-348

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Abstract

The isothermaloxidation behavior of Alrich TiAl alloys containing Y up to 10 at was studied in synthetic air with a flow of 200–250 mL/min at 800 and 900°C Oxidation kinetics and scale adherence were studied in terms of the morphological features and microstructural evolution of the oxide scale In the specimens oxidized at 800°C all alloys containing 03–10 atY showed reduced mass gain compared to the Yfree alloy especially for the 03 atY alloy Under isothermal exposure at 900°C the addition of small amounts of Y 01 and 03 at was effective in enhancing the oxidation resistance The alloys with higher Y contents 06 and 10 at on the contrary had a reverse effect on the oxidation resistance by providing rapid diffusion paths in the form of coarse Y2O3 particles close to the substrate The improvement of oxidation resistance of the alloy with Y additions was due partly to the improved adhesion of the scale and due partly to the formation of a continuous αAl2O3 layer in the outer scale Y segregation and/or Y2O3 precipitation at the oxide grain boundaries was effective in decreasing the oxidation rate and refining the oxide grains The thinner scale was responsible for relaxing the thermal stress and thus the cohesion between the scale and substrate was greatly improved in Ycontaining alloysThis work was financially supported by a GrantinAid for Scientific Research and Development from the Ministry of Education Culture Sports Science and Technology of Japan and also by ‘Priority Assistance of the Formation of World Renowned Centers of ResearchThe 21st Century COE Program Project Center of Excellence for Advanced Structural and Functional Materials Design’ from the Ministry of Education Culture Sports Science and Technology of Japan Dr Wu would like to thank the Japan Society for the Promotion of Science JSPS for a Postdoctoral Fellowship for Foreign Researchers under the contract of P02341 The help with SEM and TEM observation by Dr Hagihara is also appreciated

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