Study of the Bordoni Internal Friction Peaks in Copper

Abstract

The internal friction of several cold‐worked copper single crystals was measured between 4° and 300°K at 4 kc. Vibrational strain amplitudes ranging from 10⁻⁷−2×10⁻⁵ were used. In pure samples the height of the Bordoni relaxation peak increased slightly with strain amplitude, but in all samples the activation energy of the relaxation process was not affected. This conclusion may be reconciled with the theory of Donth—and some other aspects of the measurements (e.g., peak width) can be clarified—by assuming that the dislocations participating in the relaxation process are under internal stresses resulting from the prior cold work. An activation energy of 0.12 ev is consistent with the present data, but the range of frequency represented in the comparison is not sufficient to determine the value accurately. It is shown that the subsidiary peak consists of two separate peaks at about 30° and 40°K.