Editing Dislocation (section)

==== Surfaces ====
The surface of a crystal can produce dislocations in the crystal.  Due to the small steps on the surface of most crystals, stress in some regions on the surface is much larger than the average stress in the lattice.  This stress leads to dislocations.  The dislocations are then propagated into the lattice in the same manner as in grain boundary initiation.  In single crystals, the majority of dislocations are formed at the surface.  The dislocation density 200 micrometres into the surface of a material has been shown to be six times higher than the density in the bulk.  However, in polycrystalline materials the surface sources do not have a major effect because most grains are not in contact with the surface.