Dislocation structures and dislocation sources in deformed metals

In crystalline solids, ductility and strength are known to be governed by generation of dislocations and their motion either by glide or climb. Meanwhile, a transmission electron microscope (TEM) has been developed as an indispensable tool for studying the microstructures of crystalline solids used for various purposes. Topics related to the dislocation structures may be examined most critically by TEM observations, especially by stereo microscopy using a high voltage electron microscope. The present paper describes various types of dislocation sources, dislocation glide and climb, dislocation-dislocation interactions, and the resultant effects on the structure and strength. Brief review is made on these subjects with visual evidence obtained by TEM observations. The materials we focus on are: Al-Cu alloys stressed after quenching, Fe based shape memory alloys, Ll(2) ordered alloys for high temperature use and Al based amorphous alloys with high strength/weight ratio.