Cyclic oxidation behaviour of aluminide coatings on Ti-base alloy IMI-834 at 750 °C

Cyclic oxidation behavior of Al3Ti and Pt-aluminide coatings on the near α titanium alloy has been studied at 750 °C in air under cyclic heating and cooling conditions. Both these coatings are found to provide very good oxidation resistance to the above alloy. Even long periods of oxidation at the above temperature do not cause appreciable changes in the microstructure. It is found that, for achieving the best oxidation resistance for the Ptaluminide coatings, an optimum Pt content in the coating is needed. Through-thickness cracks that are present in both Al3Ti and Pt-aluminide coatings in as-coated condition act as easy paths for oxygen to reach the substrate which results in considerable localized damage.