Using Re-W sigma-phase first-principles results in the Bragg-Williams approximation to calculate finite-temperature thermodynamic properties
2002 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 1Article in journal (Refereed) Published
First-principles (FP) calculations of total energies for 32 different configurations of Re-W sigma phase were used to fit a compound energy formalism (CEF) Hamiltonian that was used in phenomenological Calphad method calculations to model finite-temperatures thermodynamic properties. A comparison with Connolly-Williams method-cluster variation method (CWM-CVM) calculations indicates that the first-principles CEF (FP-CEF) describes temperature-dependent site occupancies as well as the CWM-CVM approximation within the temperature range of interest for applications. This result seems to indicate that the Bragg-Williams approximation (BWA) is sufficient to describe the Re-W sigma phase. A complete Re-W phase diagram is calculated using the FP-CEF Hamiltonian for the sigma phase. Differences between the phase diagrams, and single phase properties calculated both with, and without, the first-principles results are striking. It is expected that using the FP-CEF sigma-phase description that takes into account the first-principles energetics will yield more reliable extrapolations into higher-order system.
Place, publisher, year, edition, pages
2002. Vol. 66, no 1
IdentifiersURN: urn:nbn:se:kth:diva-21792DOI: 10.1103/PhysRevB.66.012203ISI: 000177284900009OAI: oai:DiVA.org:kth-21792DiVA: diva2:340490
QC 201005252010-08-102010-08-10Bibliographically approved