Landau free energy for a bcc-hcp reconstructive phase transformation

Mahdi Sanati, A. Saxena, T. Lookman, and R. C. Albers
Phys. Rev. B 63, 224114 – Published 23 May 2001
PDFExport Citation

Abstract

We study the bcc-hcp phase transition in Ti and Zr with the use of first-principles calculations. We have determined the complete energy surface from the bcc to hcp structure. The results are used to find an appropriate Landau free energy density for describing this transformation. The proposed Landau free energy density has two relevant order parameters: shear and shuffle. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms (TA1 N-point phonon) rather than the shear. Therefore, we reduce the two order parameter Landau free energy to an effective one order parameter (shuffle) potential, which is a reasonable approximation. In general, the effective Landau free energy is a triple-well potential. From the phonon dispersion data and the change in entropy at the transition temperature we find the free energy coefficients for Ti and Zr.

  • Received 15 September 2000

DOI:https://doi.org/10.1103/PhysRevB.63.224114

©2001 American Physical Society

Authors & Affiliations

Mahdi Sanati

  • National Renewable Energy Laboratory, Golden, Colorado 80401

A. Saxena, T. Lookman, and R. C. Albers

  • Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545

References (Subscription Required)

Click to Expand
Issue

Vol. 63, Iss. 22 — 1 June 2001

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×