Kinetics and Morphology of the Oxide Growth by Oxidation of NiAl Coatings on Nickel

摘要

The oxidation of NiAl coatings on unalloyed nickel has been investigated with respect to the NiAl composition. The two types of NiAl coatings, i.e., Ni-rich and Al-rich NiAl, were prepared by pack cementation. The kinetics of oxidation were determined in the temperature range 750/1000 exp 0 C. The oxidized surfaces develop in a textured structure along with, in case of the Al-rich NiAl coatings, a thicker alumina scale which can spall off leading to irregular kinetics. In Ni-rich NiAl coatings a martensitic transformation takes place due to aluminium depletion, when oxidized above 980 exp 0 C. (ERA citation 08:018259)