Comparison between the ultrasonic and the low frequency Bordoni peaks in copper

A comparison between properties of the Bordoni peaks at low and high freque ncy is realised from experimental data of attenuation and velocity obtained at Hz and MHz frequencies. The measurements were obtained in crystalline s amples, all of them cut from the same crystal lot. Significant differences on secondary propel-ties are obtained for the low and the high frequency pe aks. The high frequency relaxation is interpreted as produced by a single r elaxation process due to kink pair formation with kink diffusion in disloca tion lines, but the low frequency relaxation must be considered as a more c omplicated process. (C) 2000 Elsevier Science S.A. All rights reserved.