Radiation Hardening of Neutron‐Irradiated Copper Single Crystals. II. Interpretation

It is shown that the vacancy‐type Frank dislocation loops on {111} planes observed in neutron‐irradiated copper by means of electron microscopy lead to a decrease in the mobility of glide dislocations during plastic deformation which accounts quantitatively for the enhancement of the critical shear stress of copper single crystals caused by neutron irradiation. This follows from the analysis of measurements of the critical shear stress and of electron‐microscopical determinations of the loop density in terms of a statistical theory of thermally activated dislocation motion over barriers of different heights. No adjustable parameters enter this analysis.