Abstract:

The cyclic oxidation behavior of TiAl alloy in air was studied. The cyclic oxidation resistance of TiAl alloy is excellent up to 1073K, but beyond that three outer nodular TiO 2 layers and an inner layer with mixed TiO 2 and Al 2O 3 are formed. The cyclic oxidation resistance of TiAl alloy is improved by depositing Cr\|modified aluminide or alluminide coatings. The Cr\|modified aluminide coating exhibits excellent cyclic oxidation resistance due to formation of Al 67 Ti 26 Cr 7 layer with a ductile cubic Ll 2 structure. Aluminide coating has the tetragonal DO 22 structure which has low symmetry and offers poor ductility and toughness, resulting in an intermediate oxidation rate.

Key words: TiAl, cyclic oxidation, surface modification, aluminide coating, pack cementation