Glide and cross-slip of a-dislocations in Zr and Ti

Caillard, D.; Gaumé, M.; Onimus, F.

doi:10.1016/j.actamat.2018.05.038

Cited by 80 publications

(46 citation statements)

References 35 publications

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“…This basal slip mechanism is similar to the one already identified in Zr [24]. Because of the high energy barrier associated with such a path, basal slip will proceed through the nucleation of double kinks thanks to thermal activation, in agreement with the Peierls mechanism inferred from TEM observations [15]. The same configurations being involved for basal as for prismatic and pyramidal motion, this explains the wavy slip traces experimentally observed when basal slip is active [15,16].…”

supporting

confidence: 84%

“…Because of the high energy barrier associated with such a path, basal slip will proceed through the nucleation of double kinks thanks to thermal activation, in agreement with the Peierls mechanism inferred from TEM observations [15]. The same configurations being involved for basal as for prismatic and pyramidal motion, this explains the wavy slip traces experimentally observed when basal slip is active [15,16]. Finally, as the Peierls barrier of basal and pyramidal [11] glide are close, both basal and pyramidal slip are activated at high enough temperature [15,16].…”

supporting

confidence: 79%

“…Besides prismatic and pyramidal glide, a dislocations in hcp Ti are also known to glide in the (0001) basal planes [12][13][14]. Recent TEM observations [15,16] at and above room temperature show straight screw dislocations moving viscously in the basal planes. This deformation mode is, however, part of profuse cross slip and is always linked with prismatic glide, leading to wavy slip traces.…”

mentioning

confidence: 99%

“…This deformation mode is, however, part of profuse cross slip and is always linked with prismatic glide, leading to wavy slip traces. Caillard et al [15] have proposed that basal glide of the screw dislocations proceeds through a kinkpair mechanism, where the screw dislocation remains dissociated either in a pyramidal or prismatic plane and a kink-pair nucleates in the neighboring Peierls valley, with the kinks lying in the basal plane. A basal dissociation of the gliding dislocation will therefore not be required to allow for basal slip.…”

mentioning

confidence: 99%

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Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

Kwaśniak

Clouet

2019

Scripta Materialia

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Basal slip of a screw dislocations in hexagonal closed-packed titanium is investigated with ab initio calculations. We show that a basal dissociation is highly unstable and reconfigures to other structures dissociated in a first order pyramidal plane. The obtained mechanism for basal slip corresponds to the migration of the partial dislocations and of the associated stacking fault ribbon in a direction perpendicular to the dissociation plane. Presented results indicate that both basal and pyramidal slip will operate through the Peierls mechanism of double-kink nucleation and will be equally active at high enough temperature.

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supporting

confidence: 84%

supporting

confidence: 79%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

Kwaśniak

Clouet

2019

Scripta Materialia

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“…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%

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

Kwaśniak

Clouet

2019

Acta Materialia

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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.

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Microplasticity at Room Temperature in α/β Titanium Alloys

Hémery

Villechaise

Banerjee

2020

Metall Mater Trans A

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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.

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Glide and cross-slip of a-dislocations in Zr and Ti

Cited by 80 publications

References 35 publications

Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

Basal slip of ⟨a⟩ screw dislocations in hexagonal titanium

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

Microplasticity at Room Temperature in α/β Titanium Alloys

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