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The
diagram shows the location of atoms close to an edge dislocation line that
runs back into the screen. The green circle outlines a group of atoms close
to the dislocation line that have larger displacements (local strains)
than permitted in a continuum model of the material. This cylindrical region
surrounding the dislocation line is known as the dislocation core.
For
the edge dislocation shown, the A atoms are more closely spaced than atoms
in the undistorted lattice and this region of the core is in compression.
The B-atoms are further apart than in the undistorted lattice and this
is a region of tension. Continuum elasticity yields an elastic stress infinity
at the core. Atomic models suggest that the strain energy per unit length
of the core region is on the order of 1 eV/atom plane. |
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