Abstract
A study was conducted to examine the isothermal oxidation behavior of a wrought Ni-Cr-Al-Fe-Y alloy in air at temperatures in the range of 950-1150°C. Oxidation kinetics were determined from weight-change measurements. Analytical electron microscopy, scanning electron microscopy, and x-ray diffraction were used to characterize the morphology, structure, and composition of the oxide scale. Overall oxidation of the alloy was found to follow parabolic kinetics. Under steady-state conditions, the oxidation reaction appeared to be controlled by diffusional transport in an adherent Y-modified α-Al2O3 scale with an activation energy of about 400 KJ/mol. Yttrium was found to preferentially segregate to grain boundaries of α-Al2O3 which maintained a fine columnar grain structure about 0.05-0.2 μm in size. Based upon the results obtained, it was suggested that the role of Y was to promote the formation of a thin layer of α-Al2O3 with improved mechanical strength.
| Original language | English |
|---|---|
| Pages (from-to) | 143-166 |
| Number of pages | 24 |
| Journal | Oxidation of Metals |
| Volume | 37 |
| Issue number | 3-4 |
| DOIs | |
| State | Published - Apr 1992 |
Keywords
- Ni-base alloy
- isothermal oxidation
- surface scale
- yttrium-effect
- α-AlO scale
ASJC Scopus subject areas
- Inorganic Chemistry
- Metals and Alloys
- Materials Chemistry