Effect of Cr on the high temperature oxidation of L12-type Al3Ti intermetallics

Three kinds of L12-type Al3Ti–Cr alloys, Al67Ti25Cr8, Al66Ti24Cr10 and Al59Ti26Cr15, were prepared by induction melting followed by thermomechanical treatment. The oxidation behavior was investigated at 1273, 1373 and 1473 K in air. The oxidation resistance of the prepared alloys was excellent, however, there were some differences for each alloy. The isothermal oxidation resistance increased in the order of Al59Ti26Cr15, Al66Ti24Cr10 and Al67Ti25Cr8, while the order became reversed in terms of the cyclic oxidation resistance. As more Al2O3 formed owing to the increased Al content in the alloy, the isothermal oxidation resistance increased, whereas the cyclic oxidation resistance decreased. The oxide scale was primarily composed of Al2O3, contaminated with Cr2O3 and TiO2 that were present mainly at the lower part the oxide scale.