DISLOCATION RELAXATION SPECTRA IN PLASTICALLY DEFORMED REFRACTORY BCC METALS

Technical Report · Tue Aug 01 00:00:00 EDT 1961

DOI:https://doi.org/10.2172/4843488· OSTI ID:4843488

Chambers, R. H.; Schultz, J.

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)

• Research Organization: General Atomics, San Diego, CA (United States)
• DOE Contract Number: AT(04-3)-167
• NSA Number: NSA-15-028033
• OSTI ID: 4843488
• Report Number(s): GA-2379
• Resource Relation: Other Information: This paper was presented at the Conference on Internal Friction due to Crystal Lattice Imperfections held at Cornell Univ., Ithaca, N.Y., on July 10-12, 1961. Orig. Receipt Date: 31-DEC-61
• Country of Publication: United States
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ANNEALING
ATOMS
COLD WORKING
DEFECTS
DEFORMATION
DISLOCATIONS
DUCTILITY
EXCITATION
FREQUENCY
FRICTION
GRAIN BOUNDARIES
HEAT TREATMENTS
HOT WORKING
IMPURITIES
INTERSTITIAL ATOMS
INTERSTITIALS
LATTICES
LOW TEMPERATURE
MOLYBDENUM
MOTION
NIOBIUM
RECRYSTALLIZATION
REFRACTORIES
SPECTRA
STRESSES
TANTALUM
TEMPERATURE
THERMODYNAMICS
TRACE AMOUNTS
TUNGSTEN