Author: Julius Frankel
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ISBN:
Category :
Languages : en
Pages : 17
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When a metal undergoes small plastic deformation, there is a change in its apparent Young's Modulus and internal friction. Both of these quantities recover following the deformation. This experiment was made to study the decrease of ultrasonic attenuation in copper single crystals following small plastic deformation. The change in the attenuation of an ultrasonic wave in a stressed single crystal does not take place smoothly. This work indicates that more than one recovery process is involved, and that the most clearly measured process has an activation energy of 1.5ev.
Author: Julius Frankel
Publisher:
ISBN:
Category :
Languages : en
Pages : 46
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Copper single crystals of 99.9% purity were deformed about .5% in tension at temperatures in the range 332.5 to 368K. The ultrasonic attenuation was measured continuously after deformation at a frequency of about 17Mc. During the measurement the specimen was in the load-off condition and at the deformation temperature. It is found by use of the Granato, Hikata and Lucke recovery theory, that the Cottrell-Bilby 't(2/3)' strain aging law is obeyed in the recovery of the ultrasonic attenuation. In most cases the use of an incubation time is required which differentiates between the time the deformation stopped and the time at which the t(2/3) law seems to take effect. The recovery parameters for the three low temperature runs plotted against 1/kT yield 1.0 plus or minus 0.2 ev as the activation energy for migration of the deformation-formed defect. The defect is therefore identified as the vacancy. It was possible to determine the approximate time after deformation stopped for which the pinning point density on the dislocations is a maximum. These times can be correlated with the times obtained by Birnbaum's low temperature strain-aging technique. (Author).
Author:
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ISBN:
Category : Science
Languages : en
Pages : 908
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Category : Aeronautics
Languages : en
Pages : 308
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ISBN:
Category : Government publications
Languages : en
Pages : 1576
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Author: American Society for Metals
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ISBN:
Category : Metal-work
Languages : en
Pages : 404
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Author: Deutsche Rheologische Gesellschaft
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ISBN:
Category : Rheology
Languages : en
Pages : 874
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Author: Acoustical Society of America
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ISBN:
Category : Sound
Languages : en
Pages : 1116
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Author: George Armand Alers
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ISBN:
Category : Deformations (Mechanics)
Languages : en
Pages :
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Author:
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ISBN:
Category : Science
Languages : en
Pages : 1030
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