Effects of temperature and ferromagnetism on the γ-Ni/γ′- Ni3Al interfacial free energy from first principles calculations

Zugang Mao, Christopher Booth-Morrison, Elizaveta Plotnikov, David N Seidman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

The temperature dependencies of the γ(f.c.c.)-Ni/γ′- Ni3Al(L12) interfacial free energy for the {100}, {110}, and {111} interfaces are calculated using first-principles calculations, including both coherency strain energy and phonon vibrational entropy. Calculations performed including ferromagnetic effects predict that the {100}-type interface has the smallest free energy at different elevated temperatures, while alternatively the {111}-type interface has the smallest free energy when ferromagnetism is absent; the latter result is inconsistent with experimental observations of γ′-Ni3Al-precipitates in Ni-Al alloys faceted strongly on {100}-type planes. The γ(f.c.c.)-Ni/ γ′-Ni3Al interfacial free energies for the {100}, {110}, and {111} interfaces decrease with increasing temperature due to vibrational entropy. The predicted morphology of γ′-Ni3Al(L1 2) precipitates, based on a Wulff construction, is a Great Rhombicuboctahedron (or Truncated Cuboctahedron), which is one of the 13 Archimedean solids, with 6-{100}, 12-{110}, and 8-{111} facets. The first-principles calculated morphology of a γ′-Ni 3Al(L12) precipitate is in agreement with experimental three-dimensional atom-probe tomographic observations of cuboidal L12 precipitates with large {100}-type facets in a Ni-13.0 at.% Al alloy aged at 823 K for 4096 h. At 823 K this alloy has a lattice parameter mismatch of 0.004 ± 0.001 between the γ(f.c.c.)-Ni-matrix and the γ′-Ni3Al-precipitates.

Original languageEnglish (US)
Pages (from-to)7653-7659
Number of pages7
JournalJournal of Materials Science
Volume47
Issue number21
DOIs
StatePublished - Nov 1 2012

ASJC Scopus subject areas

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

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