Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

Kwaśniak, Piotr; Clouet, Emmanuel

doi:10.1016/j.scriptamat.2018.11.027

Cited by 26 publications

(18 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…E inter SF−X is the interaction energy of the stacking fault with the solute atom. Its calculations is described in Appendix C. Using for the core radius r c = a √ 3/2 ∼ 2.55Å, the same value as in our previous study [29], one obtains the results shown as solid lines in Fig. 4.…”

Section: Energy Variationmentioning

confidence: 67%

“…Above room temperatures, where the friction associated with this locking-unlocking glide mechanism becomes negligible, the lattice friction originates from the interaction of interstitial solute elements, in particular oxygen which is inevitably present in titanium alloys, with the core of the screw dislocations [17,19,28]. As for secondary slip systems, ab initio calculations have shown that a screw dislocations gliding in pyramidal or basal planes need to overcome a high energy barrier [27,29], thus leading to a mobility controlled by the nucleation and propagation of kink pairs in both cases [21,27].…”

Section: Introductionmentioning

confidence: 99%

“…It is then appealing to correlate this variation of the stacking fault energies with the decrease of the ratio between the CRSS of basal and prismatic slips which has been experimentally observed with Al addition. But this assumption is nevertheless questionable as ab initio calculations in pure Ti have shown that a basal dissociation of the a screw dislocation is indeed unstable and that the screw dislocation can glide in a basal plane while remaining dissociated in a prismatic or a pyramidal plane, thus without developing any basal stacking fault [29]. One can thus wonder if a basal dissociation of the screw dislocation can be stabilized by an addition of simple metals, thus offering an explanation to the decrease of the CRSS ratio between basal and prismatic slip.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of simple metals on the stability of 〈a〉 basal screw dislocations in hexagonal titanium alloys

Kwaśniak

Clouet

2019

Acta Materialia

Self Cite

View full text Add to dashboard Cite

Basal slip acts as a secondary deformation mode in hexagonal close-packed titanium and becomes one of the primary mechanisms in titanium alloyed with simple metals. As these solute elements also lead to a pronounced reduction of the energy of the basal stacking fault, one can hypothesize that they promote basal dissociation of dislocations which can then easily glide in the basal planes. Here, we verify the validity of this hypothesis using ab initio calculations to model the interaction of a screw dislocation with indium (In) and tin (Sn). These calculations confirm that these simple metals are attracted by the stacking fault existing in the dislocation core when it is dissociated in a basal plane, but this interaction is not strong enough to stabilize a planar configuration, even for a high solute concentration in the core. Energy barrier calculations reveal that basal slip, in the presence of In and Sn, proceeds without any planar dissociation, with the dislocation being spread in pyramidal and prismatic planes during basal slip like in pure Ti. The corresponding energy barrier is higher in presence of solute atoms, showing that In and Sn do not ease basal slip but increase the corresponding lattice friction. This strengthening of basal slip by solute atoms is discussed in view of available experimental data.

show abstract

Section: Energy Variationmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of simple metals on the stability of 〈a〉 basal screw dislocations in hexagonal titanium alloys

Kwaśniak

Clouet

2019

Acta Materialia

Self Cite

View full text Add to dashboard Cite

show abstract

“…Basal slip appears also easier than pyramidal slip in titanium, with screw dislocations gliding through a slow and viscous motion compatible with a Peierls mechanism [7]. As ab initio calculations have shown that a a screw dislocation dissociated in a basal plane is unstable in titanium [37], basal glide in titanium is also realized without any basal dissociation. The same mechanism, where the screw dislocation glides in a basal planes trough the nucleation and propagation of kink-pairs while remaining dissociated in another plane, either prismatic or pyramidal, is therefore expected in titanium.…”

Section: Discussionmentioning

confidence: 97%

Secondary slip of screw dislocations in zirconium

Maras,

Clouet

2021

Preprint

Self Cite

View full text Add to dashboard Cite

Plasticity in hexagonal close-packed zirconium is controlled by screw dislocations which easily glide in the prismatic planes where they are dissociated. At high enough temperatures, these dislocations can deviate out of the prism planes to also glide in the first order pyramidal and basal planes. To get a better understanding of these secondary slip systems, we have performed molecular dynamics (MD) simulations of a screw dislocation gliding in a basal plane. The gliding dislocation remains dissociated in the prism plane where it performs a random motion and occasionally cross-slips out of its habit plane by the nucleation and propagation of a kink-pair. Deviation planes are always pyramidal, with an equal probability to cross-slip in the two pyramidal planes on both sides of the basal plane, thus leading to basal slip on average. Basal slip appears therefore as a combination of prismatic and pyramidal slip in the high stress regime explored in MD simulations. This is confirmed by nudged elastic band (NEB) calculations. But NEB calculations also reveal a change of glide mechanism for a decreasing applied stress. At low stress, kinks do not lie anymore in the pyramidal planes. They are now spread in the basal planes, thus fully compatible with a motion of the screw dislocation confined to the basal plane as seen in experiments. Basal slip, which is in competition with pyramidal slip, appears therefore favoured at low stress in pure zirconium.

show abstract

“…[36] Perhaps non-intuitively for those familiar with slip in fcc metals, there is no stable core dissociation in basal planes of Ti, and as a consequence, glide in the basal plane has all the features of a Peierls mechanism where screw orientation can be locked by dissociation on either prismatic or pyramidal planes. [37,38] Fig. 6-Slip and twinning systems in the a phase.…”

Section: B Deformation Modesmentioning

confidence: 99%

Microplasticity at Room Temperature in α/β Titanium Alloys

Hémery

Villechaise

Banerjee

2020

Metall Mater Trans A

View full text Add to dashboard Cite

The current understanding of room temperature microplasticity in a/b titanium alloys is reviewed with a special emphasis on dual-phase engineering alloys. As the interplay between microstructure and deformation mechanisms governs both the microscale and macroscale mechanical response, a brief description of the main features of a/b microstructures is first provided. Elastic and plastic deformation in individual phases is then described. The complex interactions that govern the effect of grain boundaries, phase interfaces and microtexture on deformation behaviour are reviewed. Crystal plasticity simulations have evolved over the past decade as a key technique to obtain a mechanistic understanding of the deformation of Ti alloys. Micromechanical aspects are emphasized with a discussion of input parameters required to achieve realistic constitutive modeling. As microplasticity is especially relevant in cyclic loading such as experienced in-service by components, the current understanding of the relation of this regime with fatigue and dwell-fatigue behavior is briefly summarized in the final section.

show abstract

Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

Cited by 26 publications

References 31 publications

Influence of simple metals on the stability of 〈a〉 basal screw dislocations in hexagonal titanium alloys

Influence of simple metals on the stability of 〈a〉 basal screw dislocations in hexagonal titanium alloys

Secondary slip of screw dislocations in zirconium

Microplasticity at Room Temperature in α/β Titanium Alloys

Contact Info

Product

Resources

About