Thermodynamic evaluation of the phase equilibria and glass-forming ability of the Ti-Be system

Tatsuya Tokunaga, Hiroshi Ohtani, Mitsuhiro Hasebe

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The glass-forming ability of Ti-Be alloys is of great interest. Experimental and theoretical evaluations of the glass-forming ability of this binary alloy show that the formation of a meta-stable TiBe phase with a CsCl-type B2 structure controls the glass-forming ability in this system. However, there is no information on the thermochemical properties of metastable TiBe for the quantitative evaluation of the glass-forming ability using Davies-Uhlmann kinetic formulations. We have carried out a thermodynamic analysis using experimental phase diagram data and the energy of formation of the stoichiometric compounds from ab initio calculations. Furthermore, the Gibbs energy of formation for the body-centered cubic (bcc) phase was evaluated over the entire composition range by applying the cluster expansion method (CEM) to the total energy of some bcc-based ordered structures obtained from ab initio calculations. For the bcc phase, the two-sublattice formalism, (Ti, Be)0.5(Ti, Be)0.5, was adopted to describe the A2/B2 transformation. A good agreement between the calculated values and experimental phase equilibria was obtained. Evaluation of the glass-forming ability was also attempted utilizing the thermodynamic quantities obtained from the phase diagram assessment. The calculated glass-forming ability agrees well with the experimental results.

Original languageEnglish
Pages (from-to)83-91
Number of pages9
JournalJournal of Phase Equilibria and Diffusion
Volume27
Issue number1
DOIs
Publication statusPublished - 2006 Feb
Externally publishedYes

Keywords

  • Ab initio calculations
  • CALPHAD
  • Entropy of fusion
  • Glass-forming ability
  • Metastable
  • Phase equilibria
  • Titanium-beryllium

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry

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