Pt diffusion in B2-type ordered NiAl intermetallic compound and its diffusion mechanisms

Y. Minamino, Y. Koizumi, N. Tsuji, M. Morioka, K. Hirao, Y. Shirai

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19 Citations (Scopus)

Abstract

Diffusion of platinum element which increase protectivity of NiAl layer for hot corrosion and oxidation of Ni-base superalloys was investigated in NiAl compound with compositions of 43.7-51.9 at% Al at 1373-1673 K by the diffusion couple method. The diffusion coefficients, DPt, exhibit a large concentration dependence of valley type-shape; the DPt has the minimum value quite near the stoichiometric composition and it increases with deviation from the stoichiometry. On the other hand, the activation energy, Q, shows the maximum value near the stoichiometry. Q slightly decreases with Ni composition in Ni-rich side, while it decrease dramatically with Al composition in Al-rich side. Diffusion of platinum element in NiAl occurs mainly by the Triple defect mechanism at stoichiometry, by the anti-site atom bridge mechanism in considerably off-stoichiometry in Ni-rich side and by the next nearest neighbor-jump mechanism with constitutional Ni vacancies in quite off-stoichiometry in Al-rich side.

Original languageEnglish
Pages (from-to)237-249
Number of pages13
JournalScience and Technology of Advanced Materials
Volume1
Issue number4
DOIs
Publication statusPublished - 2000 Dec 1

Keywords

  • Activation energy
  • Anti-site atoms
  • Diffusion
  • Divacancy
  • Frequency factor
  • Intermetallic compound
  • Nearest neighbor jumps
  • Next nearest neighbor jumps
  • NiAl
  • Ordering
  • Platinum
  • Triple defects
  • Vacancies

ASJC Scopus subject areas

  • Materials Science(all)

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