Variation of Elastic Modulus and Internal Friction Peaks of Commercial Copper and Copper Alloy with Resonance Method

Abstract

Squared resonant frequency and internal friction in commercial copper and copper alloy rolled sheets are measured as a function of temperature. Using adequate high temperature background of internal friction raw data enabled to separate into different internal friction peaks reflecting various relaxation mechanisms. Appearance of the highest peaks of internal friction for oxygen free copper and iron particles dispersion copper alloy C19419 was the same temperature. Because of this temperature in the vicinity of 0.6Tm, these internal friction peaks were presumed the reflection of grain boundary relaxation mechanism. Activation energy of the highest peak for C19419 alloy was estimated about 200kJ/mol. Another internal friction peaks for the OFC and C19419 copper alloy were found at 400K. Because of appearing of these peaks especially after annealed or cooling process from high temperature to room temperature, these peaks were presumed the reflection of dislocation lines pinning.