Subsurface characterization of an oxidation-induced phase transformation and twinning in nickel-based superalloy exposed to oxy-combustion environments

Jingxi Zhu, Gordon R. Holcomb, Paul D. Jablonski, Adam Wise, Jia Li, David E. Laughlin, Seetharaman Sridhar

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

In the integration of oxy-fuel combustion to turbine power generation system, turbine alloys are exposed to high temperature and an atmosphere comprised of steam, CO 2 and O 2. While surface and internal oxidation of the alloy takes place, the microstructure in the subsurface region also changes due to oxidation. In this study, bare metal coupons of Ni-base superalloys were exposed in oxy-fuel combustion environment for up to 1000h and the oxidation-related microstructures were examined. Phase transformation occurred in the subsurface region in Ni-based superalloy and led to twinning. The transformation product phases were analyzed through thermodynamic equilibrium calculations and various electron microscopy techniques, including scanning electron microscopy (SEM), orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). The mechanism by which the phase transformation and the formation of the microstructure occurred was also discussed. The possible effects of the product phases on the performance of the alloy in service were discussed.

Original languageEnglish (US)
Pages (from-to)243-253
Number of pages11
JournalMaterials Science and Engineering A
Volume550
DOIs
StatePublished - Jul 30 2012
Externally publishedYes

Keywords

  • High temperature oxidation
  • Oxy-fuel combustion
  • Phase transformation
  • Superalloy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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