Temperature Dependence of Flow Stress in Gamma Ray Irradiated Sodium Chloride Crystals

The mechanisms of radiation hardening in sodium chloride crystals were studied by examining the stress-strain curves and the temperature dependence of the flow stress. It was found that the flow stress of pure crystal is far more temperature insensitive than those which were doped with Ca ++ -ions both before and after irradiation. The experimental results were compared with the Fleischer's theory of the temperature dependence of the flow stress and a qualitative agreement was obtained for both crystals in the temperature range from 77°K to 300°K. Possible mechanisms of the radiation hardening were discussed on the basis of the present results.