Equilibrium Configurations of Dislocations under Stress: Comparison of Experimental Observations with Theory

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Abstract
Single crystals of copper were compressed and irradiated with fast neutrons while under load to pin dislocations in their stress‐applied positions. Thin electron‐microscope samples were prepared with surfaces parallel to the primary slip plane, and micrographs were taken of dislocations lying in this plane. The equilibrium shapes of these dislocations were compared with those predicted by the theory of DeWit and Koehler. A computer and digitally controlled plotter were used to generate curves representing the theoretical dislocation shapes, and these curves were plotted on transparent film for superposition onto micrographs of dislocations. The stresses thus measured on dislocations observed in samples compressed to 40, 100, and 500 gm/mm2 resolved shear stress were found to agree closely with the applied stress, even through a majority of the dislocations studied were in the vicinity of other dislocations, which might be expected to modify the stress acting on the dislocations studied.