ULTRASONIC STUDIES OF DISLOCATION DYNAMICS AND OF THE DEFORMATION OF SOLIDS.
Summary technical rept. 29 Mar 66-10 Jan 67,
BROWN UNIV PROVIDENCE R I METALS RESEARCH LAB
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The report consists of two parts, 1 plastic deformation of gallium single crystals, 2 amplitude dependence of ultrasonic attenuation in lead single crystals. In the case of gallium, it is found that the dislocations do not contribute to the attenuation of ultrasonic waves of 10 Mcsec or higher frequencies, despite the fact that the gallium crystals undergo plastic deformation with well defined dislocation glide. This phenomenon is quite in contrast to that observed in other metal single crystals such as aluminum, and is tentatively attributed to the large frictional resistance against the high velocity motion of dislocations. In the case of lead, large amplitude-dependent attenuation is observed at low temperatures. At 4.2K, a maximum in attenuation as a function of ultrasonic amplitude is found. From this attenuation maximum, it is possible to reduce the values of the electron contribution to the damping constant and of the interaction force between point defects and dislocations. Author
- Metallurgy and Metallography
- Solid State Physics