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This content will become publicly available on November 20, 2018

Title: Structural Evolution of a Ni Alloy Surface During High-Temperature Oxidation

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 CO 2 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.
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [2]
  1. National Energy Technology Lab. (NETL), Albany, OR (United States); AECOM, Albany, OR (United States)
  2. National Energy Technology Lab. (NETL), Albany, OR (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0030-770X; PII: 9821; TRN: US1800420
Accepted Manuscript
Journal Name:
Oxidation of Metals
Additional Journal Information:
Journal Name: Oxidation of Metals; Journal ID: ISSN 0030-770X
Research Org:
National Energy Technology Lab. (NETL), Albany, OR (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
20 FOSSIL-FUELED POWER PLANTS; 36 MATERIALS SCIENCE; Nickel alloy; Transient oxidation; Chromia former; Void formation; Recrystallization
OSTI Identifier: