At even smaller grain sizes of down to approx. 0.5 μm the dominant features are dislocation bundles and random dislocations, although at a larger compressive strain of 30% dislocation rotation boundaries may also be found in the interior of grains of this size.
A zero-displacement and a zero-rotation boundary condition were imposed on the nodes along the foramen magnum (Fig. 5a, b).
The boundary condition was as follows: the pterygoid processes as fixed points, the upward and downward, forward and backward, and right and left displacement was constrained and it was imposed on zero-displacement and zero-rotation boundary conditions on the nodes along the horizontal segmented plan above the nasal floor (Fig 1).
It has three stages: (1) formation of elongated cells and subgrains; (2) increased misorientation between neighboring grains and breakup of elongated grains into smaller units; and (3) rotation of boundaries by grain boundary rotation and formation of equiaxed structure.
(f) Structural diagram of rotation grain boundary.
Numerical results are presented to show the effects of chirality angle, nonlocal parameter, moderate rotation, and boundary conditions of CNTs.
Grain rotation, grain boundary sliding or migration, dislocation motion and intergranular activities are observed in the deformation process.
There are eight rotation grain boundaries in InSb NW as shown in Figure 3a.
In Figure 3a, the dark contrast area represents the [1 10] orientation indexed by 1, while the bright contrast area represents the [1 10] orientation indexed by 2. The interfaces between bright areas and dark areas indicate the rotation grain boundaries.
Several mechanisms may contribute concurrently to the plastic deformation of nanocrystalline materials (grain-boundary sliding, grain-boundary rotation, and the generation of dislocations at grain-boundaries) [84].
All of these three effects may increase the resistance for grain-boundary sliding, grain-boundary rotation, and the generation of dislocations at grain-boundaries.
