Large vibrational effects upon calculated phase boundaries in Al-Sc.
The fcc portion of the Al-Sc phase diagram is calculated from first principles including contributions to alloy free energies associated with ionic vibrations. It is found that vibrational entropy accounts for a 27-fold increase in the calculated solubility limits for Sc in fcc Al at high temperatures, bringing calculated and measured values into very good agreement. The present work gives a clear example demonstrating a large effect of vibrational entropy upon calculated phase boundaries in substitutional alloys.
Ozoliņs
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Sandia National Laboratories, MS 9161, P.O. Box 969, Livermore, California 94551-0969, USA.
Asta
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