ABSTRACT
The dislocation strengthening of metals and their alloys is perhaps one of the major technological accomplishments of the last 100 years. For example, the strength of pure metals such as aluminum and nickel have been improved by factors of 10-50 by the use of defects that restrict dislocation motion in a crystal subjected to stress. The defects may be point defects (solutes or interstitials), line defects (dislocations), surface defects (grain boundaries or twin boundaries), and volume defects (precipitates or dispersions). The strain fields that surround such defects can impede the motion of dislocations, thus making it necessary to apply higher stresses to promote the movement of dislocations. Since yielding and plastic flow are associated primarily with the movement of dislocations, the restrictions give rise ultimately to intrinsic strengthening.
