The oxidation of alloys

A review of the principles governing alloy oxidation is presented together with the means by which practical oxidation-resistant alloys have been developed. The reactions involved are complex and involve acquiring data from many fields. Wagner developed the basic diffusional models for the formation of oxide scales, but these need to be expanded using detailed physical and metallurgical studies of the alloy phases, oxides and their defects, as well as the mode of scale formation and the structural relationships between alloy and oxide scale. At this time the engineering solutions have outstripped fundamental understanding, but an attempt is made to show how the development of oxidation theory has contributed to this effort by a term now referred to as 'informed empiricism'. There is no doubt that further fundamental studies will help improve present alloys in the continuing requirements of new atmospheres and higher temperatures. (author)