| Numéro |
J. Phys. Colloques
Volume 42, Numéro C5, Octobre 1981
ICIFUAS-7Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids |
|
|---|---|---|
| Page(s) | C5-55 - C5-60 | |
| DOI | https://doi.org/10.1051/jphyscol:1981507 | |
Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. Colloques 42 (1981) C5-55-C5-60
DOI: 10.1051/jphyscol:1981507
AMPLITUDE-DEPENDENT INTERNAL FRICTION IN HIGH PURITY MOLYBDENUM SINGLE CRYSTALS IN THE TEMPERATURE RANGE 5.9 - 300 K
H.J. Kaufmann1, 2, 3, P.P. Pal-Val1, D. Schulze1, 2 et V.I. Startsev11 Physico-Technical Institute of Low Temperatures, Academy of Sciences of the Ukr.SSR, Kharkov, USSR
2 Akademie der Wissenschaften der DDR, Zentralinstitut für Festköperphysik und Werkstofforschung, Dresden, DDR
3 Akademie der Wissenschaften der DDR, Otto-Nuschke-Strasse 22/23, 1080 Berlin, DDR
Abstract
Amplitude and temperature dependences of internal friction in molybdenum single crystals of the orientations <100>, <110>, <111>, <941> are studied. The residual resistance ratio of the samples is (1-2)x105. The measurements are carried out at the frequency of 88 kHz in the temperature range 5.9 -- 300 K. It has been established that at high temperatures the amplitude-dependent internal friction is due to the process of thermally activated dislocation unpinning from the pinning centres. At low temperatures a maximum is found in the amplitude dependences the height of which decreases with decreasing temperature, but its position does not depend on the temperature. In the same amplitude range a saturation region appears in the modulus defect amplitude dependences. Such a behaviour of the high-amplitude internal friction at low temperatures can not be explained in the framework of the theories present.