THERMAL CONVERSION OF INTERSTITIALS IN ELECTRON IRRADIATED COPPER.

A study by internal friction measurements has been made on high‐purity copper of the effects of 1‐MeV electron irradiation on the rate of addition of point defects to dislocations in the temperature range 78–400°K. A distinct minimum in the point‐defect pinning rate is observed at about 160°K. It is also observed that a peak in the decrement as a function of irradiation time occurs, having a peak‐position time dependence which reflects the rate at which point defects arrive at dislocations. The above observations are discussed and taken as directed experimental evidence in support of the thermal‐conversion model. The maximum in internal friction and the minimum in the pinning rate are accounted for in a model of damping due to the dragging of point defects by dislocations.