Anelastic study of screw-dislocation motion in high-purity tantalum

Journal Article · Sat Dec 31 23:00:00 EST 1994 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(95)90282-1· OSTI ID:6550079

Mizubayashi, H; Egashira, H; Okuda, S ^[1]

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1. Univ. of Tsukuba, Ibaraki (Japan). Inst. of Materials Science

The kink pair formation (KPF) process on screw dislocations in Ta was investigated by means of the anelastic creep (AEC) measurements near room temperature. The effect of [sigma][sub eff] on H[sub KPF] and that on [nu][sub 0] were investigated for [sigma][sub eff] below 16 MPa, where [sigma][sub eff] denotes the effective stress applied to screw dislocations responsible for the AEC through KPF, H[sub KPF] the activation enthalpy of the KPF process, and [nu][sub 0] the pre-exponential factor of the inverse of the relaxation time of the KPF process. The extrapolation of the observed [sigma][sub eff] dependence gives 2H[sub k] = 0.97 [+-] 0.03 eV and 1n[[nu][sub 0,0](s[sup [minus]1])] = 29.6 [+-] 1, where H[sub k] denotes the enthalpy of an isolated single kink and [nu][sub 0,0] is [nu][sub 0] at [sigma][sub eff] = 0. Both H[sub KPF] and [nu][sub 0] show a strong decrease with increasing [sigma][sub eff]. These features for H[sub KPF] and [nu][sub 0] are very similar to those reported for Nb and Fe after the AEC measurements. The authors surmise that a change in the core structure of screw dislocation plays an important role for the rate of KPF on screw dislocations in the b.c.c. metals. The AEC results are discussed together with the strong decrease in H[sub KPF] with increasing [sigma][sub eff] reported for Fe, Nb and Ta after the flow stress measurements.

• OSTI ID: 6550079
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 43:1; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
ELEMENTS
ENTHALPY
FLOW STRESS
LINE DEFECTS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
METALS
PHYSICAL PROPERTIES
SCREW DISLOCATIONS
STRESSES
TANTALUM
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS