On recovery of dislocations in subgrains and subgrain coalescence

Abstract

A model is presented for the recovery of dislocations in the subgrain interiors and in the subboundaries. In addition to the pairwise annihilation the transfer of dislocations between the interior and the boundaries is considered. It is demonstrated that the recovery of the dislocations in the subgrain interiors in general occurs in two steps: first by pairwise annihilation and then by absorption at the boundaries, the latter process being essentially slower. The contribution from two mechanisms for subgrain coalescence is derived: extraction and emission of dislocations from the subboundaries. These contributions are compared to that from migration of boundary dislocations derived by Li. A comparison is also made to the subgrain growth rate due to subboundary migration. The two latter contributions which both involve the collective migration of dislocations, and are therefore conveniently referred to as such, are identical up to a numerical factor and occur consequently always together. Comparison to experiments will be made in a forthcoming paper.