Low-temperature point defects and dislocation study from megahertz ultrasonic measurements in aluminium

Ultrasonic measurements are made during quasi-static stress cycle applied to pure aluminium, plastically deformed at 90 K. It appears that changes in attenuation vs. stress (amplitude of stress less than 100 g/mm2), measured on the one hand at low temperature after isochronal annealings, and on the other hand during a linear temperature increase, are strongly dependent on these thermal treatments. The results are discussed in terms of dislocations and point-defect configurations. The interpretation is correlated to previous low-frequency internal friction results obtained on the same material