Predicting metastable phase boundaries in Al-Cu alloys from first-principles calculations of free energies: The role of atomic vibrations

C. Ravi*, C. Wolverton, V. Ozoliņš

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Metastable precipitate phase boundaries are difficult to ascertain experimentally and yet are important for controlling the microstructure of precipitation-hardenable alloys. We demonstrate how first-principles calculations of configurational and vibrational free energies can be used to predict precipitate phase boundaries of stable and metastable phases in Al-Cu alloys. Surprisingly, the formation entropy of a Cu impurity is found to be hugely positive (+2.7 kB/atom), leading to a dramatic enhancement in the solubility. The large entropy is dominated by the very low-frequency vibration of the small impurity atom (Cu) inside the large cage of the host (Al). The agreement between the GGA and experimental data is within 100 K for all phases, showing that accurate first-principles determination of metastable phase boundaries is now possible.

Original languageEnglish (US)
Pages (from-to)719-725
Number of pages7
JournalEurophysics Letters
Volume73
Issue number5
DOIs
StatePublished - Mar 1 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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