Statistical Thermodynamical Studies on the Fundamental Reactions concerning Steel-Making. I

The statistical thermodynamical method was introduced to the studies on the fundamental reactions concerning the steel-making apart from the use of usual chemical thermodynamical methods, which are based on the stoichiometric chemical equations constructed to represent these reactions. In this paper, as the first step, the following two problems were discussed from the view points of statistical thermodynamics : (1) The equilibrium between γ iron and CO-CO_2 gas mixture. (2) The equilibrium betweee molten iron and H_2-H_2O or CO-CO_2 gas mixture. In the first section, physical meaning of activity of carbon in γ solid solution was made clear by the statistical treatment of gaseous carburization equilibrium in austenite. In the second section, the equilibrium relation between the partial pressures of mixed gas and the concentration of solute atoms in the molten iron was discussed under the fundamental assumptions that the molten iron has a quasi-crystalline structure, and oxygen, hydrogen or carbon is dissolved as an atomic form into the interlattice positions of quasi-crystal. Deviations of activities of these solute atoms from the ideal behaviours were well explained by introducing the mutual interactions between these solute atoms. A brief consideration was given to the correlation between oxygen and carbon concentrations in the molten iron and it was pointed out that a deviation from the Vacher Hamilton\u27s law is expected in the high carbon region