ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Thermodynamic Assessment of Liquid Fe–Si–C System by Unified Interaction Parameter Model
Seung Hwan AhnYang Hong KimJoong-Pil ShinYoung Eun Lee
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2014 Volume 54 Issue 4 Pages 750-755


The solution behaviors of Fe–Si–C system are characterized by the formation of SiC, and the properties are defined by the value of the standard Gibbs free energy of formation of SiC, . However, a review shows that reported values of do not agree among the investigators and are shown a significant discrepancy among them as high as 16 kJ/molSiC. In order to resolve this uncertainty, new value of is assessed by reproducing experimentally determined two-fold saturation data with the UIP modeling Fe–Si–C melt. The proposed value of is given by following equation.

With the proposed , the UIP model for Fe–Si–C system was developed from the experimentally determined solubility of C and two-fold saturations of C and SiC taken from the literature reported. The resulting activity coefficients are expressed as follows:

where =–2.004+2718/T, =2.107–15803/T, εCC=9.052+4064/T, εCSi=5.101–9647/T, εSiSi=9.254+3380/T, εCCSi=–7.482+67622/T, εCSiSi=–39.72+185440/T, εSiSiSi=–35.966+98468/T, εCSiSiSi=34.05–160482/T, and εSiSiSiSi=20.921–74752/T.The model reproduces well the experimentally determined C solubility as well as the two-fold saturation of C and SiC. It also describes well the solution behaviors in a wide range of compositions and temperatures, permitting its use for various applications such as ironmaking, steelmaking, cast-iron, Si-based ferroalloys, and the low temperature liquid phase growth of electronic grade silicon carbide.

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© 2014 by The Iron and Steel Institute of Japan
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