The effect of platinum on diffusion kinetics in β-NiAl: Implications for thermal barrier coating lifetimes

Kristen A. Marino, Emily A. Carter

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Platinum is added to thermal barrier coatings (TBCs) as it is observed empirically to extend their lifetime, but the mechanism by which Pt acts is unknown. Since Pt has been proposed to alter diffusivities in NiAl, a key component of TBCs, we use first-principles quantum mechanics calculations to investigate atomic level diffusion mechanisms. Here, we examine the effect of Pt on five previously proposed mechanisms for Ni diffusion in NiAl: next-nearest-neighbor jumps, the triple defect mechanism, and three variants of the six jump cycle. We predict that Pt increases the rate of Ni diffusion by stabilizing point defects and defect clusters that are diffusion intermediates. Previously, we predicted the triple defect mechanism to be a dominant Ni diffusion mechanism; it simultaneously results in long-range Al diffusion in the opposite direction. Since Pt increases the rate of Ni diffusion, it also increases Al diffusion in NiAl, which may be key to extending the coating lifetime.

Original languageEnglish (US)
Pages (from-to)226-235
Number of pages10
JournalChemPhysChem
Volume10
Issue number1
DOIs
StatePublished - Jan 12 2009

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

Keywords

  • Alloys
  • Density functional calculations
  • Diffusion
  • Kinetics
  • Platinum

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