Study of structure of γ- and α-phases in Fe-Ni alloys near martensite transformation point. 3. Non-stability of crystal lattice and short order of shifts in α-martensite

Using the methods of electron diffraction microscopy, electron diffraction of high resolution and nuclear γ resonance (NGR), the martensite of the Fe-Ni system alloy has been studied in a wide temperature range. Regular changes in the diffusion scatter of electrons and in the NGR effect have been discovered when approaching the point of the reverse α → γ transformation, the changes being stimulated by a reduced stability of the crystalline body-centered cubic lattice of α-martensite and the appearance of the short-distance order of atom displacement. Possible types of the short-distance displacements have been considered. Their thermodynamic stability has been theoretically analyzed