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Metallurgical investigations such as recrystallization, martensitic transformation and dynamic behaviors of dislocations have been carried out with a 500 kV electron microscope. The critical foil thickness sufficient to observe the same dynamic behaviors of these phenomena as occurred in bulk specimens is about 1 µ for recrystallization in aluminum and iron alloys, and 3 µ for cell formation in aluminum. On the other hand, foil thickness which allows observation with the 500 kV electron microscope is practically above 8 µ for annealed aluminum and above 2 µ for annealed iron and copper, and it is about one half in order to allow continuous observation of the dynamic behaviors of phenomena. It is concluded that the 500 kV electron microscope has great advantages for the dynamic investigations of metals, especially of materials with the atomic number smaller than 15 such as aluminum and many of ionic crystals.

Layered cell structures in deformed copper single crystals with the [112] and the [415] tensile axes were observed by transmission electron microscopy on slices with (1̄1̄1), (11̄0), and (001). It was confirmed that cell walls are formed on planes rotated around the <112> axis on the active slip plane to a definite direction with respect to the tensile axis. The rotation angles were measured as a function of tensile stress. The slip line lengths on the two side planes were measured by optical microscopy. The slip line lengths and the ratios of the slip line lengths of edge dislocations to those of screw dislocations agree approximately with the slip distances estimated from the spacing and the rotation angle of the cell walls, assuming that the cell walls of the primary system are obstacles for primary dislocations. It is concluded that the slip line length is mainly determined by the layered cell structure.

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