置換型,侵入型正則溶液の確率過程と準正則溶液理論の改良並びに修正正則溶液理論

概要

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The kinetics of two-component regular solutions is investigated, based on the theory of stochastic processes. By selecting suitable stochastic state variables and assuming that the ratio of the transition rates per one atom is equal to that of activity coefficients per one atom, the solubility curve and the spinodal line for triangle and tetrahedral systems are calculated from the first moments of the stochastic variables in the zeroth and first approximations. Further, fluctuations in the thermal equilibrium state are calculated from the second moments. Their behaviors at and near the critical state are discussed. Results obtained show that the fluctuations are divergent on the spinodal line, manifesting the anomaly of the specific heats of the systems. Next, pressure-concentration-temperature (P.c.T.) curves for the interstitial systems are obtained, and application of the results to hydrogen-metal systems is attempted. Further, an improvement of the subregular solution theory presented by Hardy is attempted to provide improved P.c.T. curves for the solutions. A further modification of the regular solution theory is presented that provides a still further improvemrnt on the P.c.T. curves. The resurts are tested on hydrogen-metal systems, which show that the modified regular solution theory fits best to LaNi_5-H system.
2005-03-30