| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1468495 | Corrosion Science | 2015 | 10 Pages |
•High-temperature oxidation of Ni-base alloy 602 CA for up to 5470 h at 1100 °C is reported.•Simultaneous oxidation-induced depletion of Cr and Al leads to carbide dissolution in the alloy subsurface.•The carbide free zone (CFZ) formation is discussed in terms of alloy thermodynamics.•Carbon is experimentally shown to migrate from the surface to the alloy interior leading to precipitation of new carbides.•A quantitative thermodynamic–kinetic description is given for the CFZ growth showing excellent agreement with experiment.
The high-temperature oxidation resistance of the carbide strengthened nickel-base alloy 602 CA is provided by the formation of a protective outer Cr2O3 scale accompanied by internal precipitation of alumina and dissolution of Cr-rich carbides. The carbide free zone formation has been discussed in the literature to be a consequence of either chromium depletion or alloy decarburization.A new dissolution mechanism is proposed in this paper. Carbide dissolution in alloy 602 CA exposed to oxidizing atmospheres at 1100 °C was studied. The alloy microstructure was characterized by means of SEM/EDX/EPMA and GDOES. The experimental observations were substantiated by CALPHAD based computations.
