Abstract
The determination of equilibrium-state in gas-solid materials systems is of practical interest; this consists of finding the values of intensive variables such as mole-fractions, partial pressures, activities or chemical potentials of constituents that occur in the gaseous and solid phases for stipulated temperature, pressure and initial reactant-gas composition. The mass-action iterative equilibrium constant method, shown to be a direct derivative of the minimization of Gibbs free energy, was used to compute the equilibrium-state in the carburizing and decarburizing iron-carbon heat treatment systems. By suitably combining the equilibrium partial pressure data with the extent of reaction formalism, the optimum feed-gas mixtures that ensured neutral atmospheres were determined.
