Low Temperature Internal Friction of Aluminum at 1 Hz

The internal friction and shear modulus of single and polycrystals of Al were measured of 1 Hz from 4.2 to 300 °K as a function of the amount of deformation, temperature at deformation, and gamma irradiation. Two Bordoni peaks were found with activation energies of (0.16 ± 0.01)eV and (0.26 ± 0.03) eV, and attempt frequencies of 5 × 10 (12 ± 0.6) s −1 and 3 × 10 (14 ± 1.3) s −1 , respectively. The low temperature peak has a single attempt frequency, but a distribution of activation energies, while the process contributing to the other peak involves a distribution of attempt frequencies, and possibly a single activation energy. Gamma irradiation at low temperature does not effect these peaks. The relaxation strengths of the processes are a function of temperature. The annealing behavior of the Bordoni and other peaks found after low temperature deformation was also studied.