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)|
|Number of pages||6|
|Journal||Calphad: Computer Coupling of Phase Diagrams and Thermochemistry|
|State||Published - Mar 2010|
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Computer Science Applications