Abstract
Using first-principles total energies and frozen phonon calculations, we predict the thermodynamic properties (enthalpies of formation and vibrational entropies) for three phases in the Al-Mg-Si system: the stable phase (β-Mg2Si), and two metastable precipitate phases (β′ - Mg18 Si10 and β″ - Mg5 Si6). The stable fcc / β and the metastable fcc / β′ and fcc / β″ phase boundaries are obtained from a combination of the Gibbs energy of the compounds determined from first-principles and the free energy of the Al-rich solid solution (fcc phase) taken from the literature. Predicted phase boundaries show good agreement with available phase stability measurements. The present work demonstrates the capability of first-principles calculations in predicting Gibbs energies of stable and metastable phases.
Original language | English (US) |
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Pages (from-to) | 20-25 |
Number of pages | 6 |
Journal | Calphad: Computer Coupling of Phase Diagrams and Thermochemistry |
Volume | 34 |
Issue number | 1 |
DOIs | |
State | Published - Mar 2010 |
Funding
This work was funded by the National Science Foundation (NSF) through Grant Grants Nos. DMR-0205232 and 0510180. First-principles calculations were carried out in part on the LION clusters at the Pennsylvania State University supported by NSF (Grant Nos. DMR-9983532, DMR-0122638, and DMR-0205232) and the Materials Simulation Center and the Graduate Education and Research Services at PSU, and in part on the resources of the National Energy Research Scientific Computing Center supported by the Office of Science of the US Department of Energy under Contract No. DE-AC03-76SF00098. C. Wolverton was supported by the US Automotive Materials Partnership (USAMP) through the US Council for Automotive Research (USCAR), contract 07-1876.
Keywords
- CALPHAD
- First-principles calculations
- Intermetallic compounds
- Metastable phases
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Computer Science Applications