1. PLASTIC DEFORMATION & DISLOCATIONS

2. Change in shape of single crystals (grains)

3. Note intersecting planes
SLIP PLANES
In fcc copper
Note intersecting planes
More than one set of (111) planes is active due to action of CRSS equation and angles on inclination to the applied stress

4. DISLOCATIONS
EDGE DISLOCATION
Extra line of atoms is present in part of the crystal
Dislocation line is normal to Burgers vector
Generates a compression – tension couple (i.e. stress)
Tension below the dislocation
Compression above the dislocation line
Dislocation interacts with applied stress and moves
Generates plastic deformation

5. Movement of an Edge Dislocation

6. Common in crystal growth
SCREW
DISLOCATION
Common in crystal growth
Dislocation line parallel to Burgers vector

7. Screw dislocation from above
Open circles are atoms above dislocation line
Black circles are atoms below dislocation line