Structure of and ion segregation to an alumina grain boundary: Implications for growth and creep

Ivan Milas, Berit Hinnemann, Emily A. Carter

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Using periodic density-functional theory (DFT), we investigated the structure and cohesive properties of the α-alumina Σ11 tilt grain boundary, with and without segregated elements, as a model for the thermally grown oxide in jet engine thermal barrier coatings. We identified a new low-energy structure different from what was proposed previously based on electron microscopy and classical potential simulations. We explored the structure and energy landscape at the grain boundary for segregated Al, O, and early transition metals (TMs) Y and Hf. We predict that the TMs preferentially adsorb at the same sites as Al, while some adsites favored by O remain unblocked by TMs. All segregated atoms have a limited effect on grain boundary adhesion, suggesting that adhesion energies alone cannot be used for predictions of creep inhibition. These findings provide some new insights into how TM dopants affect alumina growth and creep kinetics.

Original languageEnglish (US)
Pages (from-to)1494-1508
Number of pages15
JournalJournal of Materials Research
Volume23
Issue number5
DOIs
StatePublished - May 2008

All Science Journal Classification (ASJC) codes

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

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