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Comments on the activity of carbon in liquid iron
Author(s) -
Gokcen Nev A.
Publication year - 1994
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199400940
Subject(s) - gibbs free energy , graphite , chemistry , thermodynamics , activity coefficient , physics , organic chemistry , aqueous solution
Existing data on the activity of carbon in liquid iron have been critically assessed and interpreted by using new equations derived by the author. These equations are the standard Gibbs energy of melting of graphite, the graphite‐liquid iron saturation equation, and the interrelationship in the Margules equation. The resulting equation is g 2 = 130,330 ‐ 32.19 T ‐ (108,330 ‐ 15.47 7) x 1 2 ‐ (344,000 ‐ 220.4 T) x 1 2 x 2 + (512,500 ‐ 380.3 7) x 1 2 x 2 2 where g 2 is the partial excess Gibbs energy of dissolved carbon in J/mol, T is the temperature in K, and x 1 and x 2 are the mole fractions of iron and carbon in the melt, respectively. g 2 refers to graphite as the standard state so that g 2 = R T In γ 2 = ‐ R T ln x 2 (at graphite saturation), where R is the gas constant, and γ 2 is the activity coefficient. From the preceding equation, g 1 for iron has been obtained.