Dislocation unpinning model of acoustic emission from alkali halide crystals |
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| Authors: | B P Chandra Anubha S Gour Vivek K Chandra Yuvraj Patil |
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| Institution: | (1) School of Studies in Physics, Pt. Ravi Shankar Shukia University, 492 010 Raipur, India;(2) Department of Electronics and Telecommunication, Raipur Institute of Technology, 492 101 Raipur, India;(3) Department of Physics, Government Digvijay P.G. College, 491 441 Rajnandgaon, India |
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| Abstract: | The present paper reports the dislocation unpinning model of acoustic emission (AE) from alkali halide crystals. Equations
are derived for the strain dependence of the transient AE pulse rate, peak value of the AE pulse rate and the total number
of AE pulse emitted. It is found that the AE pulse rate should be maximum for a particular strain of the crystals. The peak
value of the AE pulse rate should depend on the volume and strain rate of the crystals, and also on the pinning time of dislocations.
Since the pinning time of dislocations decreases with increasing strain rate, the AE pulse rate should be weakly dependent
on the strain rate of the crystals. The total number of AE should increase linearly with deformation and then it should attain
a saturation value for the large deformation. By measuring the strain dependence of the AE pulse rate at a fixed strain rate,
the time constantτ
s for surface annihilation of dislocations and the pinning timeτ
p of the dislocations can be determined. A good agreement is found between the theoretical and experimental results related
to the AE from alkali halide crystals. |
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| Keywords: | Acoustic emission dislocation alkali halide crystals plastic deformation |
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