First-principles phase stability calculations of pseudobinary alloys of (Al,Zn) 3Ti with L1 2, D0 22, and D0 23 structures

Gautam Ghosh*, Axel Van De Walle, Mark Asta

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The thermodynamic and mechanical stability of intermetallic phases in the Al 3Ti-Zn 3Ti pseudobinary alloy system is investigated from first-principles total energy calculations through electronic density-functional theory within the generalized gradient approximation. Both supercell calculations and sublattice-cluster-expansion methods are used to demonstrate that the addition of Zn to the Al sublattice of Al 3Ti stabilizes the cubic L1 2 structure relative to the tetragonal D0 22 and D0 23 structures. This trend can be understood in terms of a simple rigid-band picture in which the addition of Zn modifies the effective number of valence electrons that populate bonding and anti-bonding states. The calculated zero-temperature elastic constants show that the binary end members are mechanically stable in all three ordered phases. These results point to a promising way to cost effectively achieve the stabilization of L1 2 precipitates in order to favor the formation of a microstructure associated with desirable mechanical properties.

Original languageEnglish (US)
Pages (from-to)9-22
Number of pages14
JournalJournal of Phase Equilibria and Diffusion
Volume28
Issue number1
DOIs
StatePublished - Feb 2007

Keywords

  • Cluster expansion
  • Computational studies
  • Crystal structure
  • Elastic properties
  • Electronic structure
  • First principles
  • Intermetallics

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry

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