Structural Evolution of a Ni Alloy Surface During High-Temperature Oxidation
- National Energy Technology Lab. (NETL), Albany, OR (United States); AECOM, Albany, OR (United States)
- National Energy Technology Lab. (NETL), Albany, OR (United States)
We show that considerable structural transformations occur at a Ni alloy surface during the transient stages of high-temperature oxidation. This was demonstrated by exposing the alloy to high-temperature CO2 for short times at both atmospheric and supercritical pressures. A protective Cr-rich oxide layer formed after only 5 min at 700 °C and persisted for longer exposures up to 500 h. Voids formed and grew over time by the condensation of metal vacancies generated during oxidation, while the alloy surface recrystallized after sufficient oxidation had occurred. The oxygen potential established at the oxide/alloy interface led to oxidation along the newly formed grain boundaries as well as adjacent to and inside of the voids. Al, the most stable oxide-former and present at low concentration in the alloy, was preferentially oxidized in these regions. Furthermore, the results provide an improved understanding of the internal oxidation of Al and its role in enhancing scale adhesion for this class of Ni alloys.
- Research Organization:
- National Energy Technology Lab. (NETL), Albany, OR (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE)
- OSTI ID:
- 1413213
- Report Number(s):
- NETL-PUB-21369; PII: 9821; TRN: US1800420
- Journal Information:
- Oxidation of Metals, Vol. 90, Issue 1-2; ISSN 0030-770X
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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