The dislocation-internal friction peak. gamma. in tantalum

Journal Article · Fri Mar 31 23:00:00 EST 1989 · Acta Metallurgica; (USA)

DOI:https://doi.org/10.1016/0001-6160(89)90111-9· OSTI ID:5579164

Baur, J ^[1]; Benoit, W ^[2]; Schultz, H ^[3]

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1. ALUSUISSE, CH-3965 Chippis (CH)
2. Ecole Polytechnique Federale, Lausanne (Switzerland)
3. Postfach 7000, D-7250 Leonberg (DE)

Torsion-pendulum measurements were carried out on high-purity single crystal specimens of tantalum, having extremely low oxygen contents (<1 at. ppm), and on similar specimens doped with small, controlled amounts of oxygen (7 at. ppm). Our investigations are mainly concerned with the {gamma} peak, which is usually explained by kink-pair formation in screw dislocations, and with the {gamma}/sub 2/ peak, which appears close to {gamma} is small traces of oxygen are presents. The {gamma}/sub 2/ peak was formerly explained as a dislocation-enhanced Snoek peak . The {gamma} peak recovers at the peak temperature, whereas the {gamma}/sub 2/ peak is more stable. On the basis of their results, and making use of earlier investigations of Rodrian and Schultz, the authors suggest that {gamma}/sub 2/ is modified {gamma} relaxation, related to screw-dislocation segments, stabilized by oxygen-decorated kinks. The stability of the {gamma}/sub 2/ peak allows an accurate determination of the activation energy, found to be 1.00 +- 0.03 eV. This value is distinctly lower than the activation energy of the oxygen Snoek effect (1.10 eV) and is related here to the mechanism of kink-pair formation in screw dislocations, as the original {gamma} peak. The numerical value is compatible with recent values derived from flow-stress measurements. The peak {gamma}/sub 2/ shows increasing stability with increasing oxygen content. This is explained by single- and multi-decorated kinks.

• OSTI ID: 5579164
• Journal Information: Acta Metallurgica; (USA), Journal Name: Acta Metallurgica; (USA) Vol. 37:4; ISSN 0001-6160; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals &amp; Alloys-- Structure &amp; Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric &amp; Radiochemical Procedures
656001* -- Condensed Matter Physics-- Solid-State Plasma
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
CRYSTALS
DISLOCATION PINNING
ELEMENTS
ENERGY
INSTABILITY
INTERACTIONS
KINK INSTABILITY
METALS
MONOCRYSTALS
NONMETALS
OXYGEN
PAIR PRODUCTION
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SOLID-STATE PLASMA
TANTALUM
TRANSITION ELEMENTS