Electron Microscopic Study of Single Crystal Films of NaCl Containing CaCl2

Electron microscopic study of single crystal films of NaCl containing CaCl 2 was performed in more detail than that previously reported (J. Phys. Soc. Japan 19 (1964) 1892), with respect to climb motion of grown-in dislocations during observation and with respect to precipitation of CaCl 2 . A characteristic interaction between climbing dislocations was observed and the sign of climb motion was determined to be positive by a new method based upon the characteristic black-and-white aspect of a dislocation image near the foil surfaces, which is due to the anomalous absorption effect. It was also concluded that as incipient precipitates nucleate, they introduce an abnormal 1/6<112> type displacement in the matrix along {111} precipitation planes and they preferentially nucleate on a dislocation causing dissociation of it into two partial segments. The climb motion is discussed in connection with the observations and a model for the nucleation and growth process of the precipitate is given.