Slip by Dislocation Movement
The concept of the dislocation was first introduced to explain the discrepancy between the observed and theoretical shear strengths of metals.
For the dislocation concept to be valid it is necessary to show
- (1) that the motion of a dislocation through a crystal lattice requires a stress far smaller than the theoretical shear stress, and
- (2) that the movement of the dislocation produces a step, or slip band, at the free surface.