J. Phys. Colloques
Volume 48, Numéro C8, Décembre 1987Fifth European Conference on Internal Friction and Ultrasonic Attenuation in Solids
|Page(s)||C8-77 - C8-82|
J. Phys. Colloques 48 (1987) C8-77-C8-82
ULTRASONIC ATTENUATION IN POLYCRYSTALLINE 5N ALUMINIUMW.E. ALNASER1 et D.H. NIBLETT2
1 Physics Department, Bahrain University, PO Box 1082, Bahrain
2 Physics Laboratory, The University, GB-Canterbury CT2 7NR, Kent, Great-Britain
The ultrasonic attenuation of 5N purity polycrystalline aluminium has been measured over the temperature range from 110 to 300K at a frequency of 10 MHz, using a conventional pulse echo technique with a single quartz transducer. Five specimens were used and each was subjected to a series of deformations by compression, the plastic strain ranging up to about 20% For the higher deformations two dislocation relaxation peaks (Bordoni and Niblett-Wilks peaks) were observed at about 226 and 168K respectively, superimposed on attenuation due to other sources. The Bordoni peak was not observed after low levels of deformation, only the Niblett-Wilks peak being evident at these strains. Our results are compared with previous measurements on similarly-strained 5N aluminium at other frequencies and indicate that the activation energies for the Bordoni and Niblett-Wilks peaks are about 0.22 and 0.15 eV respectively.