Acoustic Characteristics of Twinning in Indium.
JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICS AND MATERIALS SCIENCE
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Since mechanical twinning is one of the major causes of fatigue failure in metals, acoustic emission measurements were made during mechanical deformation of indium single crystals. Indium was selected since upon stress application well delineated twins develop which can be made to disappear upon stress reversal. Associated with this twinning and detwinning are high intensity acoustic emissions and therefore indium affords an excellent material with which to develop techniques. By recording the acoustic emission signals on a video tape recorder it was possible to play them back as often as desired, to observe them in slow and stop motion, and to play any desired portion of the signal through a spectrum analyzer for frequency analysis. The experimental results show that a correspondence exists between the duration of the acoustic signal and the volume of twinned material as determined by cinematographic observation of the generation and growth of twin bands.
- Metallurgy and Metallography