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- Title
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
- Abstract
A thermodynamic model for calculating the mass action concentrations $$ N_{i} $$ of structural units in Fe-O binary melts based on the atom-molecule coexistence theory, i.e., AMCT- $$ N_{i} $$ model, has been developed and verified to be valid through comparing with the calculated activities $$ a_{{{\text{R,}}i}} $$ of both O and Fe over a temperature range from 1833 K to 1973 K (1560 °C to 1700 °C). Moreover, activity coefficients $$ \gamma_{\text{O}}^{{}} $$ or $$ f_{{{\%,{\text O}}}} $$ or $$ f_{\text{H,O}} $$ of O coupled with activity $$ a_{\text{R,O}} $$ or $$ a_{{{\% , \text{O}}}} $$ or $$ a_{\text{H,O}} $$ of O and the corresponding first-order activity interaction coefficient $$ \varepsilon_{\text{O}}^{\text{O}} $$ or $$ e_{\text{O}}^{\text{O}} $$ or $$ h_{\text{O}}^{\text{O}} $$ of O to O have also been determined by the developed AMCT- $$ N_{i} $$ 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 $$ N_{\text{Fe}} $$ of free Fe are in good agreement with results of the calculated activity $$ a_{\text{R,Fe}} $$ of Fe relative to pure liquid Fe(l) as standard state in Fe-O binary melts. The calculated mass action concentration $$ N_{\text{O}} $$ of free O has a closely corresponding relationship with the calculated activity $$ a_{\text{R,O}} $$ of O relative to ideal O at 101,325 Pa as standard state in Fe-O binary melts. However, values of the calculated mass action concentration $$ N_{\text{O}} $$ of free O are much greater than results of the calculated activity $$ a_{\text{R,O}} $$ of O in Fe-O binary melts. The converted mass action concentration $$ N_{\text{O}}^{\prime} $$ of total O relative to ideal O at 101,325 Pa as standard state can be obtained through transferring standard state of the calculated mass action concentration $$ N_{\text{O}} $$ of free O. The converted mass action concentration $$ N_{\text{O}}^{\prime} $$ of total O or the converted activity $$ a_{\text{R,O}}^{\text{AMCT}} $$ of O can well be matched with the calculated activity $$ a_{\text{R,O}} $$ of O in Fe-O binary melts. Although the obtained expression of first-order activity interaction coefficient $$ \varepsilon_{\text{O}}^{\text{O}} $$ or $$ e_{\text{O}}^{\text{O}} $$ or $$ h_{\text{O}}^{\text{O}} $$ by the developed AMCT- $$ N_{i} $$ model for Fe-O binary melts is different with that based on the calculated activity $$ a_{\text{R,O}} $$ or $$ a_{{{{\%,{ \text O}}}}} $$ or $$ a_{\text{H,O}} $$ of O, they can be applied to accurately predict activity $$ a_{\text{R,O}} $$ or $$ a_{{{{\%, {\text O}}}}} $$ or $$ a_{\text{H,O}} $$ 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 $$ N_{\text{O}}^{\prime} $$ of O or the converted activity $$ a_{\text{R,O}}^{\text{AMCT}} $$ of O as well as the calculated mass action concentration $$ N_{\text{Fe}} $$ of [Fe] by the developed AMCT- $$ N_{i} $$ model for Fe-O binary melts.
- Subjects
THERMODYNAMICS; CHEMICAL reactions; MOLECULAR structure; ANALYTICAL chemistry; ENTHALPY
- Publication
Metallurgical & Materials Transactions. Part B, 2016, Vol 47, Issue 1, p174
- ISSN
1073-5615
- Publication type
Article
- DOI
10.1007/s11663-015-0482-z