Some effects of electron irradiation on the internal friction of copper

Abstract

Studies have been made of the variations of the internal friction of pure copper after electron irradiation at about 100°K and room temperature. The results are interpreted in terms of the pinning of dislocation lines by point defects. The variation of the room temperature internal friction with electron energy and dose is consistent with a displacement energy for an atom in copper of 20–25 ev. On warming up the sample after irradiation at 100°K, the damping was found to decrease in two temperature ranges, beginning at approximately 200°K and 270°K. The decrease is attributed to defects becoming mobile at these temperatures. The relation of these regions of defect movement to the electrical resistance annealing stages is discussed.