Suppression of anomalous slip by oxygen interstitials in vanadium

Bressers, J.; Creten, R.

doi:10.1016/0036-9748(77)90008-4

Cited by 16 publications

(2 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Consequently, the two dislocations may move easily in parallel planes while introducing little work hardening. However, these observations are at odds with experiments on V [16,17], where the (0 11) slip also appears in compression.…”

Section: Structures and Glide Of Isolated 1/2[111] And [100] Screw Di...mentioning

confidence: 75%

Origin of variable propensity for anomalous slip in body-centered cubic metals

Gröger¹

2022

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

Many transition metals crystalizing in the body-centered cubic (bcc) structure exhibit anomalous slip on low-stressed {110} planes at low homologous temperatures, which cannot be reconciled with the Schmid law. Speciﬁcally, for uniaxial loading in the center of the [001] - [011] - [-111] stereographic triangle, this is manifested by 1/2[111] and 1/2[1-1-1] screw dislocations moving on low-stressed (0-11) planes. While the anomalous slip is often attributed to non-planar cores of 1/2<111> screw dislocations or to the tendency for their networks to glide easily, it remains unclear why it dominates the plastic deformation in some bcc metals, whereas it is weak or even absent in others. Using molecular statics simulations at 0 K, we demonstrate that the anomalous slip in bcc metals is intimately linked with the stability of <100> junctions between two intersecting 1/2<111> screw dislocations under stress (for example, 1/2[111] and 1/2[1-1-1] screws giving rise to the [100] junction). Our atomic-level studies show that in nearly all bcc metals of the 5th and 6th groups these junctions cannot be broken by the applied stress and the three dislocations can only move on the common {110} plane (in the above example on the (0-11) plane). On the other hand, these junctions are found to be unstable in alkali metals, tantalum, and iron, where the application of stress results in unzipping of the two dislocations and their further glide on the planes predicted for isolated dislocations. These results also suggest that the experimentally observed increased propensity for the anomalous slip in further stages of plastic deformation may be explained by reduced curvatures of 1/2<111> screw dislocations in dense networks.

show abstract

Section: Structures and Glide Of Isolated 1/2[111] And [100] Screw Di...mentioning

confidence: 75%

Origin of variable propensity for anomalous slip in body-centered cubic metals

Gröger¹

2022

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…a strong temperature dependence of the yield stress and anomalous slip. The latter has been studied most extensively in ~-Fe and in Nb, however, this slip mode has been observed in other b.c.c, metals as well, such as Ta [2][3][4][5], V [6][7][8] and Mo [9,10]. The occurrence of the slip is anomalous as the slip plane observed belongs to one of the {110} planes with a small Schmid factor [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Dislocation dynamics in vanadium: A nuclear magnetic resonance and transmission electron microscopic study

Christian

Kanert

Hosson

1990

Acta Metallurgica et Materialia

View full text Add to dashboard Cite

Pulsed nuclear magnetic resonance proved to be a complementary new technique for the study of moving dislocations in b.c.c, metals. From the motion induced part of the spin-lattice relaxation rate the mean jump distance of mobile dislocations has been measured in Vanadium as a function of temperature. The NMR experiments are combined with transmission electron microscopic investigations to reveal the static structure of defects in the samples. The NMR experiments show that the mean jump distance is nearly constant below 230 K whereas it decreases substantially above 230 to 300 K indicating a transition that marks two different mechanisms. NMR observations in combination with TEM support the physical picture that above the transition temperature dislocation segments are stopped between localized obstacles whereas below T c the lattice friction controls the plastic behaviour.

show abstract

Anomalous Slip in High-Purity Niobium and Tantalum Single Crystals

Wasserbäch

1995

Phys. Stat. Sol. (a)

View full text Add to dashboard Cite

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.

show abstract

Suppression of anomalous slip by oxygen interstitials in vanadium

Cited by 16 publications

References 13 publications

Origin of variable propensity for anomalous slip in body-centered cubic metals

Origin of variable propensity for anomalous slip in body-centered cubic metals

Dislocation dynamics in vanadium: A nuclear magnetic resonance and transmission electron microscopic study

Anomalous Slip in High-Purity Niobium and Tantalum Single Crystals

Contact Info

Product

Resources

About