| Numéro |
J. Phys. Colloques
Volume 48, Numéro C8, Décembre 1987
Fifth European Conference on Internal Friction and Ultrasonic Attenuation in Solids
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|---|---|---|
| Page(s) | C8-77 - C8-82 | |
| DOI | https://doi.org/10.1051/jphyscol:1987807 | |
J. Phys. Colloques 48 (1987) C8-77-C8-82
DOI: 10.1051/jphyscol:1987807
ULTRASONIC ATTENUATION IN POLYCRYSTALLINE 5N ALUMINIUM
W.E. ALNASER1 et D.H. NIBLETT21 Physics Department, Bahrain University, PO Box 1082, Bahrain
2 Physics Laboratory, The University, GB-Canterbury CT2 7NR, Kent, Great-Britain
Abstract
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.