Ultrasonic Methods in the Study of Fatigue and Deformation in Single Crystals of Aluminum and Sodium Chloride

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Report Number: ASD TDR 62-186
Author(s): Chick, Bruce, Anderson, George, Findley, William , Elbaum, Charles , Truell, Rohn, Hikata, Akira
Corporate Author(s): Brown University
Laboratory: Directorate of Materials and Processes
Date of Publication: 1963-02
Pages: 37
Contract: AF 33(616)-6945
DoD Project: 7360
DoD Task: 736002
Identifier: AD0408704

The use of ultrasonic methods (and in some cases electrical conductivity measurements) for study ing defect formation and motion in connection with deformation and stress cling experiments in aluminum and sodium chloride single crystals is the subject. Recovery in aluminum single crystals at 195 K was compared with recovery at room temperature and an interesting 'threshold effect' was observed; there appears to be a level of deformation which must be exceeded at this temperature before recovery occurs. The auto matic recording time echo (or velocity) measure ment unit was designed to measure the time be tween two successive echoes in a pulse echo train with a sensitivity of one nanosecond out of one hundred microseconds and to record the measure ment as a voltage capable of driving a recorder so that dynamic changes in time will produce a record. It was found that no change in center frequency or bandwidth is seen over a 40 db range of gain control nor does an artificial change of 40 db in signal level produce a detect able change in measured time.

Provenance: Lockheed Martin Missiles & Fire Control

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