The cyclic-oxidation resistance of a TiAl coupon at 1300K was significantly improved by the preoxidation at 1200K for 100ks in a pack of a mixture of 70mass% Cr
2O
3 and 30mass% metallic Cr powders. This is attributable to the formation of a thin dense scale of about 1μm thickness consisting mainly of α-Al
2O
3. The scale contains small amounts of TiO
2 and Cr
2O
3, and a very small amount of metallic Cr on its surface. The scale became thicker very slightly after ten-cycle oxidation (720ks) with no significant structural changes. Other combinations of temperature (1100, 1200, and 1300K) and pack composition (100, 70, and 30% Cr
2O
3 with balance of metallic Cr) lead to the formation of poorly protective scales. There is a general trend; when temperature is low or the amount of Cr
2O
3 in the pack is small, thin defective scales very rich in Al are formed, while when temperature is high or the Cr
2O
3 content is large, thick porous scales consisting of TiO
2 and Al
2O
3 are developed. The above can be explained in terms of the rate of oxygen supply.
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