Thermodynamic analysis of the Mg-RE-Zn (RE = Y, La) ternary hcp phase using the cluster variation method

Satoshi Iikubo, Shuji Hamamoto, Hiroshi Ohtani

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13 Citations (Scopus)

Abstract

In this study, thermodynamic properties of the Mg-RE-Zn (RE = Y, La) ternary hcp phase at finite temperature have been investigated by means of first-principles calculations combined with the cluster variation method (CVM). Free energy calculation, including the configurational entropy, shows that the Mg-Y-Zn ternary hcp phase has a tendency to phase separation. Conversely, the Mg-La-Zn ternary system does not exhibit such behavior even around room temperature. Furthermore, the calculated spinodal region extends to a broader composition range and the maximal spinodal temperature reaches above 1000K for the Mg-Y-Zn system. Conversely, the spinodal region for the Mg-La-Zn system is a limited narrow region near the Mg-rich side, and the maximal spinodal temperature is 300 K. Formation enthalpies calculated on the basis of recent information from structure analyses do not show a definite difference in these two ternary systems. Therefore, we propose that the dominant factors in the formation of a novel long period stacking ordered structure include spinodal decomposition as well as structure transformation from 2H to other structures having periodic stacking faults.

Original languageEnglish
Pages (from-to)636-640
Number of pages5
JournalMaterials Transactions
Volume54
Issue number5
DOIs
Publication statusPublished - 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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