THE INFLUENCE OF POINT DEFECT ORIENTATION UPON DISLOCATION MOBILITY IN KCl

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Abstract
Point defects having less than cubic symmetry are known to be much more effective solution-hardening agents in cubic materials than those possessing such symmetry. Solution-hardening theories predict that for certain relative orientations of the dislocation Burgers vector and the anisotropic defect the hardening effectiveness should be reduced or entirely absent. The theory was tested by measuring the solution hardening in KCl:Ag irradiated at liquid nitrogen temperature. The principal hardening agents are Cl2− defects most of which can be aligned parallel to a chosen crystal direction by irradiation with polarized light. The experiments showed that the hardening effectiveness of the defects was about 20% less when they were aligned than when they were randomly distributed. This finding is in qualitative agreement with the theory, but etching experiments failed to confirm the directional character to the dislocation point defect interaction.
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