Real Materials

· Dislocation motion in crystals can occur when a shear stress act across the slip plane. This is illustrated for an edge dislocation.
· The atomic structure is only adjusted in the region of the dislocation line during this motion.

From: Hull, "Introduction to Dislocations," Pergamon (1965)

· This local process that is less energetically expensive than breaking and remaking all the bonds across the slip plane.
· Dislocations can move in crystals at speeds up to the speed of sound, the velocity of elastic waves in the material.
· The Dislocation motion causes plastic deformation of the material. The passage of a single dislocation completely across the slip plane displaces the material above the plane by b with respect to material below the plane.