αFe中の熱空孔の生成に及ぼす磁気転移の影響

抄録

In the processes of precipitations and phase transformations, thermal vacancies play an important role through diffusions of atoms. Due to magnetic transitions, the thermal vacancy fraction becomes smaller in the ferromagnetic state comparing to the paramagnetic state. In this work, the effect of magnetic transitions on the vacancy formation was examined using Inden model for the magnetic excess Gibbs energy, which has been widely applied in the CALPHAD-type thermodynamic assessments. In the present work, the effect of magnetic transitions on S_Fe^Mag/R and H_Fe^Mag is estimated to be 0 ~ –0.5 and 0 ~ 0.06 eV, respectively, The differences between ferromagnetic and paramagnetic states of αFe are +0.06 eV for the enthalpy of vacancy formation, and −0.435 R for the entropy of vacancy formation.