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INTRACRYSTALLINE MOVEMENTS

Limited to a single individual crystal only and can be in the form of point defects or line defects or planar defects. The first of these can be achieved by any of the mechanisms such as the diffusional creep mechanisms. The second can be accomplished by dislocation glide and the third by deformation twinning. In contrast, the inter- crystalline movements are not confined to a single crystal but a group of crystals, such as grain boundary sliding (GBS) or grain boundary migration (GBM) or pressure solution.

INTRA- AND INTERCRYSTALLINE PROCESSES

1. Dislocation Glide- leads to internal deformation of individual grains, and hence of grain boundaries

2. Twinning- leads to internal deformation of individual grains, and hence of grain boundaries

3. Climb- can lead to internal deformation of individual grains, and hence of grain boundaries

4. Nabarro Herring Creep- leads to internal deformation of individual grains, and hence of grain boundaries

5. Kinking- leads to internal deformation of individual grains, and hence of grain boundaries

6. Cracking- leads to generation of new grain boundaries, their orientation can be either crystallographically controlled or by orientation of stress field, or some combination of both.

7. Rotation Recrystallisation- newly formed subgrains are typically fairly equant, so if these become sufficiently reoriented to become new grains, they will degrade the grain shape foliation.