EVOLUTION OF OXIDES ON NI-BASE ODS SUPERALLOYS

Mechanically-alloyed Ni-base ODS superalloys currently receive attenti on for application in future gas turbines because they exhibit outstan ding mechanical properties at high temperatures. They also protect the mselves against oxidation by forming chromia and/or alumina scales. Ho wever, little attention has been given so far to the initial stages of oxidation of Ni-base ODS superalloys, containing Cr as well as Al in considerable amounts. In the current work, oxidation at 1150 degrees C was studied for different holding times up to 200 hr for the commerci al materials MA6000 and PM3030 which contain Al in increasing amounts. MA754, a chromia former, was investigated as a reference. It was show n that for the potential alumina formers MA6000 and PM3030 the continu ity and therefore protectiveness of the secondary Al2O3 at later stage s is indeed determined by the initial stages of oxidation.