Bonding characteristics of micro-alloyed B2 NiAl in relation to site occupancies and phase stability

Y. L. Hao, R. Yang, Q. M. Hu, D. Li, Y. Song, M. Niinomi

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A recently developed mean-field model has been combined with first principles calculations of binding energy to investigate the site occupancies of micro-alloying elements and vacancies in NiAl as well as the stability of the micro-alloyed B2 phase with respect to disordering and second-phase formation. The theoretical results suggest that the transition metal elements in the same row of the periodic table increasingly tend to the Ni sublattice with increasing atomic number. Micro-alloying addition tends to decrease the vacancy concentration of NiAl alloys. Alloying with X that substitutes for Ni is predicted to have the sides of its solubility lobe parallel to the Ni-X side of the isotherm, but parallel to the Al-X side if X substitutes for Al. Micro-alloying was shown to raise the ordering temperature of the B2 phase over the corresponding binary alloy, in contrast with the effect of vacancies. Alloying effects on ordering temperature and the formation of point defects appear independent of the site substitution behaviour, and are less significant for 3d than for 4d and 5d transition metal elements.

Original languageEnglish
Pages (from-to)5545-5554
Number of pages10
JournalActa Materialia
Volume51
Issue number18
DOIs
Publication statusPublished - 2003 Oct 20

Keywords

  • Ab initio electron theory
  • Intermetallic phases (nickel aluminides)
  • Lattice defects (vacancies)
  • Phase transformations (ordering)

ASJC Scopus subject areas

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

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