Influence of Elastic Anisotropy on the Dislocation Contribution to the Elastic Constants

Abstract

Calculations of the dislocation contribution to the measured elastic constants of face-centered cubic crystals are made as follows. First, the displacement of a pinned dislocation segment under an externally applied stress is evaluated. Then the contribution to the resulting macroscopic distortion of the specimen resulting from the motion of all the dislocations present is calculated. The results are that the contributions for given dislocation arrangements increase with increasing anisotropy. For copper and lead the contributions can amount to a few percent in a pure well annealed crystal and can be as large as 10% in slightly deformed crystals. Edge dislocations are found to make about ten times larger contributions than a similar density of screw dislocations.