Actions for DISLOCATION RELAXATION SPECTRA IN PLASTICALLY DEFORMED REFRACTORY BCC METALS

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DISLOCATION RELAXATION SPECTRA IN PLASTICALLY DEFORMED REFRACTORY BCC METALS

Author
Chambers, R. H.
Published
United States : [publisher not identified], 1961.
[Oak Ridge, Tennessee] : [U.S. Atomic Energy Commission], 1961.
Physical Description
microopaque : positive ; 8 x 13 cm
Additional Creators
Schultz, J.

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Summary
Pairs of broad, thermally activated stress-relaxation peaks were produced by room-temperature plastic deformation of the bcc transition metals Nb, Ta, and Mo. At least one peak and perhaps two existed in hot-worked tungsten. The effective activation energies of these peaks were measured by internal- friction methods at frequencies from 5 to 100,000 cps at strain amplitudes near 10/sup -7/. These mechanical-relaxation phenomena were interpreted in terms of some kind of thermally activated motion of segments of dislocation lines over intrinsic lattice-potential barriers. Relatively low-temperature anneals produced a lowering of the peak heights as well as a decrease in the peak temperature. Measurements on cold-worked molybdenum and tantalum containing small amounts of interstitial impurities showed evidence of a post-relaxation rise in the background internal friction similar to that found in lightly cold- worked copper single crystals. Increased amounts of impurities and/or heavy cold working sharply reduced this background contribution in tantalum. A thermal- aging treatment at temperatures just under the recrystallization temperature produced a large increase in the modulus as measured at room temperature but very little change as measured at 5 deg K. (auth)
Report Numbers
GA-2379
Other Subject(s)
Collection
U.S. Atomic Energy Commission depository collection.
Note
DOE contract number: AT(04-3)-167
NSA number: NSA-15-028033
OSTI Identifier 4843488
Research organization: General Atomics, San Diego, CA (United States).
View MARC record | catkey: 41840928