ULTRASONIC METHODS IN THE STUDY OF FATIGUE AND DEFORMATION IN SINGLE CRYSTALS OF ALUMINUM AND SODIUM CHLORIDE

摘要

The use of ultrasonic methods for studying defect formation and its consequences in connection with stress cycling and deformation in aluminum and sodium chloride single crystals is the subject of this report.nThe observed ultrasonic changes appeared closely associated with changes in dislocation behavior. To establish this deformation experiments ware used in such a way that results could be related to the behavior of the slip systems and to their orientation. Aluminum single crystals were used for these experiments* Simultaneous measurements of attenuation and velocity changes- were made continuously during tensile deformation. In the very early stages of deformation, for all orientations, an increase in attenuation is observed before microscopic yield. Easy glide is observed by the attenuation and velocity changes.nMeasurements in tension have been made for the purpose of comparing the dislocation damping and pinning effects in an ionic crystal with those in s metal.nImportant equipment improvements have been made for automatic recording of attenuation and velocity measurements.