The effect of annealing and electron irradiation on the internal friction in copper in the kHz range

This thesis comprises two parts, Part 1 presents an explanation of the improved measuring equipment for determining the internal friction in the kHz range, using repeated bending vibrations of thin specimens. Part 2 describes the measurements carried out for determining the internal friction in copper specimens following different types of annealing, and prior and subsequent to electron irradiation. The method applied is the ordinary one for this purpose, transforming the specimens's vibrations into capacitive changes ΔC, inducing a frequency modulation in a VHF oscillator. The method has been modified by reducing the distance between specimen and counter-electrode and by largely avoiding stray capacities, thus making ht erelative capacitive change ΔC so large that amplitudes up to 1x10-8 can be measured. With this amplitude, the deflection of the vibrating specimen tips is only 2x10-6 mm. In addition, the temperature range has been extended to 4.2 K. In non-deformed, reduced and oxidized Cn specimens bending vibrations have been induced in order to study internal friction at approx. 2 kHz. Irradiation has been made in situ with 3 MeV electrons at 4.2 K in a Van de Graaf accelerator. Reducing the recrystallisation temperature to 1023 K after annealing, dislocation pinning effects following irradiation have been achieved. (orig./IHOE)