Reassessment of the Al-Mn system and a thermodynamic description of the Al-Mg-Mn system

Yong Du, Jiong Wang, Jingrui Zhao, Julius Clemens Schuster, Franz Weitzer, Rainer Schmid-Fetzer, Munekazu Ohno, Honghui Xu, Zi Kui Liu, Shunli Shang, Wenqing Zhang

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Abstract

A thermodynamic optimization for the Al-Mn system is performed by considering reliable literature data and newly measured phase equilibria on the Al-rich side. Using X-ray diffraction, differential thermal analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy methods, the melting behavior of λ-Al4Mn was correctly elucidated, and two invariant reactions associated with λ-Al4Mn (L + μ-Al4Mn ↔ λ-Al4Mn at 721 ± 2°C and L + λ-Al4Mn ↔ Al6Mn at 704 ± 2°C) are observed. The model Al12Mn4(Al, Mn) 10 previously used for Al8Mn5 was modified to be Al12Mn5(Al, Mn)9 based on crystal structure data. In addition, the high-temperature form of Al11 (Mn4 is included in the assessment. Employing fewer adjustable parameters than previous assessments, the present description of the Al-Mn system yields a better overall agreement with the experimental phase diagram and thermodynamic data. The obtained thermodynamic description for the Al-Mn system is then combined with those in the Al-Mg and Mg-Mn systems to form a basis for a ternary assessment. The thermodynamic parameters for ternary liquid and ternary compound Mn2Mg3Al18 (τ) are evaluated on the basis of critically assessed experimental data. The enthalpy of formation for τ resulting from CALPHAD (CALculation of PHAse Diagrams) approach agrees reasonably with that via first-principles methodology. Comparisons between the calculated and measured phase equilibria in the Al-Mg-Mn system show that the accurate experimental information is satisfactorily accounted for by the present description. A reaction scheme for the whole ternary system is presented for practical applications.

Original languageEnglish (US)
Pages (from-to)855-871
Number of pages17
JournalInternational Journal of Materials Research
Volume98
Issue number9
DOIs
StatePublished - Sep 1 2007

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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    Du, Y., Wang, J., Zhao, J., Schuster, J. C., Weitzer, F., Schmid-Fetzer, R., Ohno, M., Xu, H., Liu, Z. K., Shang, S., & Zhang, W. (2007). Reassessment of the Al-Mn system and a thermodynamic description of the Al-Mg-Mn system. International Journal of Materials Research, 98(9), 855-871. https://doi.org/10.3139/146.101547