Microstructural evolution of the interface between NiCrAlY coating and superalloy during isothermal oxidation

Y. Z. Liu, Xiaobing Hu, S. J. Zheng*, Y. L. Zhu, H. Wei, X. L. Ma

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

NiCrAlY coating was plasma-sprayed on a Ni-based single crystal superalloy and then subjected to isothermal oxidation at 1100°C in air up to 50h. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we investigate interfacial microstructure evolution of the coating induced by internal oxidation and nitridation. After 5h oxidation, α-Al2O3 and Cr2O3 sub-layers form at the coating/substrate interface. Interestingly, after 10h oxidation, pure Al phase is found at the coating/substrate interface owing to decomposition of substrate phase γ'-Ni3Al. Although, after 25h oxidation, hexagonal AlN and cubic TiN form in the substrate close to the coating/substrate interface, after 50h oxidation, AlN transforms into α-Al2O3 owing to internal oxidation while TiN remains in the substrate because of its high stability. The findings of this work provide solid experimental evidence of microstructural evolution at the coating/substrate interface, especially demonstrate the conjecture that pure metal phases and nitrides could precipitate at coating/substrate interface after high temperature oxidation.

Original languageEnglish (US)
Pages (from-to)63-69
Number of pages7
JournalMaterials and Design
Volume80
DOIs
StatePublished - Sep 5 2015

Keywords

  • Coating
  • Interface
  • Isothermal oxidation
  • Superalloy
  • Transmission electron microscopy (TEM)

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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