The pinching-off of dislocation dipoles by glide

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Abstract
The possibility of a dislocation dipole's pinching-off by cross slip either at its end or in its interior is investigated. It is concluded that the forces between the screw segments at the end of an edge dislocation dipole are repulsive, so that pinching-off will not occur unless an applied stress is present, and only if the two edge segments of the dipole are of unequal length. Pinching-off in the interior of a dipole can occur when the dipole is of predominantly screw character. In an appendix to the paper, it is shown that the stress field of a screw dislocation of finite length l is essentially one-half that of two infinitely long screw dislocations of opposite Burgers vector, separated by a distance l. This result is used to show that the minimum length of two screw dislocations that annihilate each other by cross slip must be twice the initial separation distance between the dislocations.
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