Effect of Cr on the high temperature oxidation of Ll(2)-type Al3Ti intermetallics

Three kinds of Lit-type Al3Ti-Cr alloys, Al67Ti25Cr8, Al66Ti24Cr10 and Al59 Ti26Cr15, were prepared by induction melting followed by thermomechanical t reatment. The oxidation behavior was investigated at 1273, 1373 and 1473 K in air. The oxidation resistance of the prepared alloys was excellent, howe ver, there were some differences for each alloy. The isothermal oxidation r esistance increased in the order of Al59Ti26Cr15, Al66Ti24Cr10 and Al67Ti25 Cr8, while the order became reversed in terms of the cyclic oxidation resis tance. As more Al2O3 formed owing to the increased Al content in the alloy, the isothermal oxidation resistance increased, whereas the cyclic oxidatio n resistance decreased. The oxide scale was primarily composed of Al2O3, co ntaminated with Cr2O3 and TiO2 that were present mainly at the lower part t he oxide scale. (C) 2000 Elsevier Science S.A. All rights reserved.