1979 年 43 巻 11 号 p. 1048-1055
Mössbauer nuclei 119mSn were doped into the grain boundary of ultra fine grained iron specimens. Various parameters such as internal magnetic field, Debye temperatures and thermal jump frequency were measured. The parameters showed that tin atoms segregated at the grain boundary are contributing a less amount of outer shell electrons to bonds with the neighboring atoms and the average force constant is reduced below that of tin in solid solution in the iron matrix. The differences, however, were small while a large difference was noticed in its internal magnetic field. The absence in the internal magnetic field suggests that iron atoms next to tin in the grain boundary are in a special state with respect to their d-level and may explain the embrittlement of steel. The oxygen-induced embrittlement which was suggested from experiments of pure iron may be a different mechanism peculiar to pure iron.