It is well known that materials are structure-sensitive. This means that
properties of materials, especially mechanical properties, are determined by
behavior of the lattice imperfections such as dislocations and point
defects. High resolution and quick recording of the images by electron
microscopy have been effectively used for studying behavior of lattice
imperfections. It is very difficult, however, to get a definite conclusion
about the deformation processes based on the static electron microscope
observation of the dislocation structures formed by deformation, because
many processes can be considered to get the same dislocation structure.
Therefore, dynamic study of the behavior of lattice imperfections is
necessary to carry out in order to investigate the properties of
materials.