First-principles study of interfacial boundaries in Ni-Ni3Al

C. Woodward, A. Van De Walle, M. Asta, D. R. Trinkle

Research output: Contribution to journalArticlepeer-review

Abstract

The width and energy of low-index interfacial boundaries (IFBs) in Ni-Ni3Al are calculated using first-principles methods for temperatures ranging from 0 to 1300 K. The low-temperature, coherent and chemically sharp (1 0 0), (1 1 0) and (1 1 1) IFBs are studied using conventional spin-polarized density functional methods. Cluster expansion methods, as implemented in the ATAT software suite, are used to estimate the interfacial excess free energies (IEFEs) and composition and long-range order profiles of these defects as a function of temperature. The simple face-centered cubic-based cluster expansion produces interfacial widths in the range of 1.5-3.0 nm at 1000 K. Interfacial widths double in size with an increase in temperature of 500 K. We also find that the IEFEs for the (1 0 0), (1 1 0) and (1 1 1) IFBs are strongly temperature dependent, decreasing by 90% as temperature increases from 0 to 1000 K. While vibrational and electronic entropic contributions were also considered, changes in free energy are dominated by the configurational entropy. The predicted high-temperature IEFE is approximately 10 mJ m-2 which is in excellent agreement with previous fits to experimentally measured coarsening rates.

Original languageEnglish (US)
Pages (from-to)60-70
Number of pages11
JournalActa Materialia
Volume75
DOIs
StatePublished - Aug 15 2014

Keywords

  • Ab initio calculations
  • Interfaces
  • Interfacial free energy
  • Superalloys
  • Temperature dependence

ASJC Scopus subject areas

  • Ceramics and Composites
  • Metals and Alloys
  • Polymers and Plastics
  • Electronic, Optical and Magnetic Materials

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