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The analysis of the elementary processes of fragmentation (broken sub-boundaries
and a misorientation band formation) is performed by the discrete dislocation computer
simulation method. It is shown that a fragmentation driving force is a decrease of the system
energy due to the dislocations redistribution in the elastic field of primary mesodefects
(disclinations, dipoles of disclinations et al.) accumulating on the grain boundaries and triple
junctions during plastic deformation. The comparison of the results with the results obtained
by continual approach is made. The misoriented structures formation inside shear bands
during plastic deformation of mono--crystals is considered. It is shown that this process is
similar to the polycrystal fragmentation, but in this case dislocation clusters accumulating
near shear band interface act as the primary mesodefects. An analysis of conditions of low-angle
sub-boundaries trasformation into medium-angle boundaries is performed.
Keywords: plastic deformation; fragmentation; dislocations; disclinations; computer simulation |
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