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Thermodynamic Evaluation of Reaction Abilities of Structural Units in Fe-O Binary Melts Based on the Atom-Molecule Coexistence Theory

Authors
  • Yang, Xue-Min
  • Li, Jin-Yan
  • Wei, Meng-Fang
  • Zhang, Jian
Publication Date
Feb 01, 2016
Source
Institutional Repository of Institute of Process Engineering, CAS (IPE-IR)
Keywords
License
Unknown
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Abstract

A thermodynamic model for calculating the mass action concentrations of structural units in Fe-O binary melts based on the atom-molecule coexistence theory, i.e., AMCT- model, has been developed and verified to be valid through comparing with the calculated activities of both O and Fe over a temperature range from 1833 K to 1973 K (1560 A degrees C to 1700 A degrees C). Moreover, activity coefficients or or of O coupled with activity or or of O and the corresponding first-order activity interaction coefficient or or of O to O have also been determined by the developed AMCT- model and verified to be credible. In addition, the molar mixing thermodynamic properties of Fe-O binary melts have been determined to be accurate. Values of the calculated mass action concentration of free Fe are in good agreement with results of the calculated activity of Fe relative to pure liquid Fe(l) as standard state in Fe-O binary melts. The calculated mass action concentration of free O has a closely corresponding relationship with the calculated activity of O relative to ideal O-2 at 101,325 Pa as standard state in Fe-O binary melts. However, values of the calculated mass action concentration of free O are much greater than results of the calculated activity of O in Fe-O binary melts. The converted mass action concentration of total O relative to ideal O-2 at 101,325 Pa as standard state can be obtained through transferring standard state of the calculated mass action concentration of free O. The converted mass action concentration of total O or the converted activity of O can well be matched with the calculated activity of O in Fe-O binary melts. Although the obtained expression of first-order activity interaction coefficient or or by the developed AMCT- model for Fe-O binary melts is different with that based on the calculated activity or or of O, they can be applied to accurately predict activity or or of O in Fe-O binary melts. The molar mixing thermodynamic properties such as molar mixing enthalpy change/entropy change/Gibbs energy change of Fe-O binary melts can reliably be determined from the converted mass action concentration of O or the converted activity of O as well as the calculated mass action concentration of [Fe] by the developed AMCT- model for Fe-O binary melts.

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