Dislocation Contribution to the Temperature Dependence of the Internal Friction and Young's Modulus of Copper

Abstract

A study of the amplitude‐independent internal friction and Young's modulus in copper from 14°K to room temperature, both before and after neutron irradiation, indicates that there are two dislocation components in these quantities. These have been tentatively identified as a relaxation component studied in detail theoretically by Seeger and a background component which appears to be characteristic of Koehler's bowing mechanism. It is felt that these two components are probably quite intimately related, for the background internal friction rises at just slightly higher temperatures than the maximum of the individual relaxation processes, and the activation energy of the background process is about twice the kink energy obtained from Seeger's theory. Moreover, the Bordoni, or relaxation spectrum, is shown to be considerably more complex than has been previously indicated in that there appear to be at least four principal relaxations. As a result of the analysis attempted in the present work, it appears that the more obvious difficulties of Seeger's theoretical treatment are alleviated.