Fe-Ni-Mn 3元系合金におけるスピノーダル分解と粒界反応析出

抄録

Phase decomposition and precipitation in Fe-35 at%Ni-35 at%Mn, Fe-40 at%Ni-40 at%Mn and Fe-45 at%Ni45 at%Mn alloys were Investigated by means of optical and electron microscopy, X-ray diffraction, dilatation, electrical resistivity and hardness measurements.
Spinodal decomposition in the matrix and cellular precipitation from grain boundary occur about the same time. In the matrix, high Ni and high Mn region changes into an ordered fct phase with progress of the decomposition. In the grain boundary, the primary cell shows a modulated structure and dccomposes to an fcc (or a bcc) phase and an fct phase with progress of aging. As the aging temperature rises, the primary cell becomes a lamellar structure and spinodal decomposition is hardly observed in the matrix. This lamellar structure consists of an fcc phase and an fct phase.
The composition at which the modulated cellular structure appears is the spinodal region. The composition at which the lamellar cellular structure precipitates is regaded as the miscibility gap.