Anomalous slip in high-purity vanadium crystals deformed in compression

Creten, R.; Bressers, J.; Meester, Paul De

doi:10.1016/0025-5416(77)90145-8

Cited by 21 publications

(16 citation statements)

References 13 publications

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“…The core structure in tungsten is not shown because it is practically the same as in molybdenum. For the positive τ the dislocation core extends further onto the (101) plane while it constricts on both (0 11) and (110) planes. On the other hand, for negative τ, the core constricts on the (101) plane and extends on (0 11) and (110) planes.…”

Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

“…For the positive τ the dislocation core extends further onto the (101) plane while it constricts on both (0 11) and (110) planes. On the other hand, for negative τ, the core constricts on the (101) plane and extends on (0 11) and (110) planes. Based on this observation we can surmise that for positive τ the glide of the screw dislocation on the (101) plane, driven by the shear stress σ, will be easier when compared to the case of either none or negative shear stress perpendicular to the slip direction.…”

Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

“…Hence, one may expect that for τ > 0 the CRSS will be decreasing with increasing τ. Analogously, we can speculate that negative τ makes the glide on the (101) plane increasingly more difficult and at large negative τ the (101) glide may even be suppressed owing to the large extension of the core into the other two {110} planes of the [111] zone. Instead, the dislocation glide may proceed either on the (011) or on the (110) plane even though the shear stress in the direction of the Burgers vector is in these planes smaller than in the (101) plane. In any case an appreciably larger CRSS can be expected at negative τ than when no shear stress perpendicular to the slip direction is applied.…”

Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

“…While direct experimental observations of the cores of screw dislocations are precarious [42,43], such core spreading has been found in all atomistic calculations (for reviews see [3,[44][45][46][47][48][49][50][51]). In all these studies the core was found to spread into three {110} planes, specifically (101) , (011) and (110) for the 1/2 [111] dislocation.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Multiscale modeling of plastic deformation of molybdenum and tungsten: I. Atomistic studies of the core structure and glide of 1/2〈111〉 screw dislocations at 0K

2008

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Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

Section: Loading By Shear Stress Perpendicular To the Slip Direction mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multiscale modeling of plastic deformation of molybdenum and tungsten: I. Atomistic studies of the core structure and glide of 1/2〈111〉 screw dislocations at 0K

2008

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“…5. Temperature dependence of the angle w between the macroscopically or mesoscopically observed slip plane and the primary slip plane at c ¼ 0 in Ta, Mo, Nb, and V. Sources: Ta (77 K T 300 K) [2]; Ta (1 K T 40 K) [53]; Mo [54]; Nb, residual resistivity ratio RRR ¼ 6000 (77 K T 300 K) [2]; (44 K T 77 K) [55,56]; Nb, 200 mm foils [46]; Nb, RRR ¼ 2000 [57,58]; V [21,59] points in Fig. 4 are guides to the eye; from the data one cannot conclude that the addition of Nb to Mo extends the range of anomalous glide to larger c.) The reduction with decreasing purity of the range of orientations showing anomalous slip, clearly visible in the Ta data of Fig.…”

Section: Anomalous Slip In Individual Metalsmentioning

confidence: 99%

Anomalous Slip - A Feature of High-Purity Body-Centred Cubic Metals

Seeger¹,

Wasserbäch²

2002

phys. stat. sol. (a)

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The hitherto poorly understood phenomenon of anomalous slip in body-centred cubic (bcc) metal crystals, constituting a striking violation of Schmid's law of resolved shear stresses in limited ranges of temperature and crystallographic orientation of the stress axis, is shown to be a natural consequence of the fact that the slip planes of a 0 h111i=2 screw dislocations change from f110g at low temperatures to f112g at higher temperatures. Above the temperature T T of this change, which is responsible for the so-called lower bend of the flow-stress-temperature relationship, in the orientation range of anomalous slip the two slip systems with the largest resolved shear stress have different slip directions. The screw dislocations of these systems may avoid jog formation and generation of atomic defects by cross-slipping to the anomalous f110g plane. This mechanism accounts for the dependence of anomalous slip on temperature, crystallographic orientation, and purity. The variation from metal to metal is shown to be correlated with the elastic anisotropy. Mechanisms that might be responsible for this variation, in particular for the absence of anomalous slip in bcc iron, are discussed.

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Anomalous Slip in High-Purity Niobium and Tantalum Single Crystals

Wasserbäch

1995

Phys. Stat. Sol. (a)

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High‐purity niobium and tantalum single crystals having orientations in the central part of the stereographic triangle and a residual resistance ratio RRR of better than 5500:1 are deformed in tension, compression, and by cyclic deformation at temperatures below ambient. The deformation behaviour is studied by observation of the slip‐line morphology, Laue X‐ray backreflection, X‐ray topography, and transmission electon microscopy (TEM). Anomalous (011) slip is observed at temperatures below about 200 K for the niobium crystals and at liquid nitrogen temperatures for the tantalum crystals, respectively. The influence of the specimen purity on the appearance of the anomalous slip is investigated by etching experiments: for example, etching in an acid solution subsequently suppresses anomalous slip in the tantalum specimens owing to the influence of hydrogen interstitials. Prestraining of the specimens has different effects on the appearance of the anomalous slip, depending on the temperature and the mode of the predeformation: anomalous slip is generally suppressed by prestraining unless the specimens are predeformed into stage I of the three‐stage work‐hardening curve at the appropriate temperatures. The TEM investigations reveal that the dislocation arrangement consists of regular networks of screw dislocations with primary and conjugate Burgers vectors, lying in the anomalous slip plane. The X‐ray topography investigations demonstrate that twist walls of alternating signs are built up during anomalous slip. The separation of two adjacent twist walls of alternating signs corresponds to the separation of the anomalous slip lines on the crystal surfaces. From the angle of twist the density of the excess dislocations in the twist walls is estimated to be about 3% of the total dislocation density.

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Anomalous slip in high-purity vanadium crystals deformed in compression

Cited by 21 publications

References 13 publications

Multiscale modeling of plastic deformation of molybdenum and tungsten: I. Atomistic studies of the core structure and glide of 1/2〈111〉 screw dislocations at 0K

Multiscale modeling of plastic deformation of molybdenum and tungsten: I. Atomistic studies of the core structure and glide of 1/2〈111〉 screw dislocations at 0K

Anomalous Slip - A Feature of High-Purity Body-Centred Cubic Metals

Anomalous Slip in High-Purity Niobium and Tantalum Single Crystals

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