Effect of impurity atoms on α2/γ lamellar interfacial misfit in Ti-Al alloy: A systematic first principles study

Yuichiro Koizumi, Masato Yoshiya, Atsushi Sugihara, Yoritoshi Minamino

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The effect of transition metal solutes on the lattice parameters of γ-TiAl and α 2 -Ti 3 Al were studied by first principles calculations to find suitable elements for controlling the α 2 /γ interfacial misfit in lamellar Ti-Al alloys. Better agreement was found between the calculated and experimental phase and site preferences of impurity atoms than in a previous first principles study. The calculated lattice parameters suggest that elements in groups 6-11 of the 4th period (Cr, Mn, Fe, Co, Ni and Cu) are effective for increasing the misfit, leading to increasing density of misfit dislocation and, in turn, higher yield strength and ductility. This effect is caused by the change in the lattice parameter of the γ-TiAl phase rather than those of α 2 - Ti 3 Al phase. This prediction agrees qualitatively with experimental data from a previous study although the effects of temperature are not taken into account. Further improvements should be possible by considering those effects. Nevertheless, the results highlight the effects of impurity addition on interfacial misfit at a level which cannot be achieved by classical concepts such as atomic size in a hard sphere model. The results will also be valuable in further more quantitative predictions and in understanding the effects of temperature, including off-stoichiometry, thermal expansion and vibration entropy.

Original languageEnglish
Pages (from-to)3685-3704
Number of pages20
JournalPhilosophical Magazine
Volume91
Issue number28
DOIs
Publication statusPublished - 2011 Oct 1

Keywords

  • density-functional theory
  • first-principles calculations
  • interfaces
  • intermetallics
  • lamellar boundary
  • lattice defects
  • lattice parameter
  • multilayers
  • nanostructured materials
  • ordered intermetallics
  • titanium aluminides

ASJC Scopus subject areas

  • Condensed Matter Physics

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