Comparison of thermodynamic databases for 3xx and 6xxx aluminum alloys

C. Ravi*, C. Wolverton

*Corresponding author for this work

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Computational thermodynamics, or Calculation of Phase Diagram (CALPHAD) methods have proven useful in applications to modeling a variety of alloy properties. However, the methods are only as accurate as the thermodynamic databases they use, and two commercial thermodynamic databases exist for aluminum alloys: Thermotech and Computherm. In order to provide a critical comparison of these databases, we used both the databases to calculate equilibrium solid-state phase fractions and phase diagram isothermal sections of several industrial aluminum alloys: a 319-type and 356 cast alloys, as well as the wrought alloys 6022 and 6111. All of these alloys may be generically described as being based on the Al-Mg-Si-Cu quaternary with other additions such as Fe, Mn, and Zn. Although many of the results are consistent between the two databases, several qualitative and quantitative differences were observed. Many of these differences are found to be due to the intermetallic compounds involving Fe, Mn, Cr, and Zn. On the other hand, thermodynamics involving only phases from the Al-Mg-Si-Cu quaternary show good agreement between the databases, although some small differences still exist, particularly involving the quaternary Q phase. To understand and assess these differences, formation enthalpies and reaction energies from the databases were compared against density functional first-principles energetics. These comparisons indicate possible avenues for future improvements of Al-alloy thermodynamic databases. Finally, we demonstrate an interesting correlation between the calculated phase fractions and the measured yield strengths across this wide family of 3xx cast and 6xxx wrought alloys.

Original languageEnglish (US)
Pages (from-to)2013-2023
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume36
Issue number8
DOIs
StatePublished - Aug 2005

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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