Structure, processing and properties of ODS superalloys

Abstract

The present paper reviews the technology and science of oxide-dispersion strengthened (ODS) superalloys in the light of the latest developments in COST 501 and elsewhere. The emphasis is on the alloys Inconel MA 6000 and Incoloy MA 956, on which most recent work has been performed. The essential microstructural elements in theses alloys are described and illustrated. The processing steps, including mechanical alloying, powder consolidation, recrystallization, forging, joining and machining are critically examined. Further, the properties of ODS superalloys - i.e. yield, creep, fatigue and thermal fatigue strength as well as hot corrosion resistance - are reviewd and, wherever possible, compared to those of conventional superalloys. Important property improvements over the dispersoid-free counterparts are identified and the beneficial effects of the oxide dispersoids are discussed on the basis of the latest scientific progress in this area. Finally, the scope for further development of ODS alloys with regard to alloy composition, structure, and fabricability is outlined.