Reassessment of Al-Ce and Al-Nd binary systems supported by critical experiments and first-principles energy calculations

Michael C. Gao*, Necip Ünlü, G. J. Shiflet, Marek Mihalkovic, Michael Widom

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

98 Citations (Scopus)

Abstract

The present study reinvestigates the Al-Ce and Al-Nd phase diagrams and reoptimizes their thermodynamics using the CALPHAD method. First-principles energy calculations play an important role in terms of sublattice formalism and phase-stability prediction, demonstrating that they should be effectively integrated into experimental investigations and thermodynamic assessments. Specifically, current experimental results and theoretical calculations show that Al2Nd (or Al2Ce) should be treated as a stoichiometric compound phase rather than as the solution phase that was proposed in previous studies. Further, a new compound, AlCe2, is found stable at high temperatures (648 °C to 775 °C) in the Al-Ce system. It forms through a peritectic reaction of liquid and AlCe phases at 775 °C, and decomposes into AlCe and, βAlCe3 at 648 °C and below. Since the AlCe2 phase is not retained at room temperature by quenching experiments, it is suggested that AlCe2 may be isostructural with the previously known compound AlNd2 (oP12). Based on current differential thermal analysis (DTA) measurements and theoretical calculations, it is also proposed that there is an α/βAl3Ce polymorphous transition occurring at 973 °C in the Al-Ce system and an α/βAl3Nd polymorphous transition occurring at 888 °C in the Al-Nd system. The βAl3RE phase may be isostructural with βAl3Y (hP12). Finally, the previously described βAl11RE3 phase (rare earth elements (RE) = La, Ce, Nd, or Pr) is proposed to have a stoichiometry of Al4RE (t/10), based on direct evidence from differential scanning calorimetry (DSC) measurements.

Original languageEnglish
Pages (from-to)3269-3279
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume36
Issue number12
DOIs
Publication statusPublished - Dec 2005
Externally publishedYes

Funding

Reassessment of Al-Ce and Al-Nd Binary Systems Supported by Critical Experiments and First-Principles Energy Calculations

FundersFunder number
Multi-University Research InitiativeF49602-01-1-0352
NDFDMR-0111198
U.S. Department of Energy
Office of Science

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