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The effects of reactive element additions and sulfur removal on the adherence of alumina to Ni‐ and Fe‐base alloys
Author(s) -
Meier G. H.,
Pettit F. S.,
Smialek J. L.
Publication year - 1995
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19950460407
Subject(s) - materials science , annealing (glass) , flue gas desulfurization , alloy , sulfur , oxide , hydrogen , metallurgy , doping , chemical engineering , chemistry , organic chemistry , optoelectronics , engineering
The effects of reactive element additions to alumina‐forming alloys (single‐crystal Ni‐base and ferritic Fe‐Cr‐Al alloys) and the effect of hydrogen annealing to remove sulfur on the oxide adherence to these alloys have been studied. The results have shown that desulfurization by hydrogen annealing can result in improvements in cyclic oxidation comparable to that achieved by doping with reactive elements. The results have also shown that there is less stress generation during the cyclic oxidation of Y‐doped FeCrAl compared to Ti‐doped or desulfurized FeCrAl. This indicates that the growth mechanism, as well as the strength of the oxide/alloy interface, influences the ultimate oxidation morphology and stress state which will certainly affect the length of time the alumina remains protective. It has been shown to be possible to estimate the amount of sulfur available to segregate to the alloy/oxide interface and how this is influenced by reactive element additions or hydrogen annealing. If these calculations can be made more quantitative it should be possible to engineer alumina‐forming alloys for optimum resistance to cyclic oxidation e.g. by combining an appropriate desulfurization treatment and choice of reactive element addition.