日本金属学会誌

J. Japan Inst. Metals, Vol. 57, No. 11 (1993),
pp. 1288-1292

Effect of Surface Roughness on High-Temperature Oxidation of γ-TiAl Alloy

Kazuo Kasahara1 and Masao Takeyama2

1National Research Institute for Metals, Tokyo
2Faculty of Engineering, Department of Metallurgical Engineering, Tokyo Institute of Technology, Tokyo

Abstract:

The oxidation behavior of Ti--52 mol%Al in a temperature range of 1000 to 1273 K was examined by using samples with different surface preparations. At temperatures below 1170 K, the oxidation resistance increases with increasing surface roughness, and the mass gain of the sample with sand-blasted surfaces is smaller by an order of magnitude than that of the sample with electropolished surfaces at 1000 K. The drastic increase in oxidation resistance is caused by the formation of protective aluminum-rich oxide layers on the surfaces at an early stage of oxidation, which is presumably due to a rapid diffusion of aluminum atoms form the bulk to the surface through the work-hardened layer introduced by the abrasive treatment on the surface. At higher temperatures above 1170 K, however, little difference in the mass gain is observed among the samples with different surface preparations. The titanium-rich oxide is dominantly formed on the sample surfaces, regardless of the surface preparations, leading to no positive effect of surface roughness on the oxidation resistance.


(Received March 10, 1993)

Keywords:

gamma-TiAl alloy, high-temperature oxidation, oxidation product, surface roughness


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