Motion of a screw dislocation in a two-dimensional Peierls potential

Edagawa, Keiichi; Suzuki, Takayoshi; Takeuchi, Shin

doi:10.1103/physrevb.55.6180

Cited by 54 publications

(49 citation statements)

References 20 publications

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“…This Peierls barrier is identified with the lowest energy path over the two-dimensional Peierls potential between two equivalent locations of the dislocation. This potential is, similarly as in [36], a function of the position of the intersection of the dislocation line with the {111} plane perpendicular to the corresponding 〈111〉 slip direction. In an unstressed crystal the Peierls potential possesses the three-fold rotation symmetry associated with the 〈111〉 direction as well as the periodicity of the corresponding {111} plane.…”

Section: Discussionmentioning

confidence: 99%

“…This approach is similar to that advanced in [36] but the novel concept is that the Peierls potential is considered to be a function of the full applied stress tensor. Since atomistic molecular statics calculations do not provide full information about the Peierls potential but give only the values of the Peierls stress, !…”

Section: Construction Of the Peierls Potential And The Peierls Barriermentioning

confidence: 99%

“…However, 1/2 〈111〉 screw dislocations in BCC metals do not have unique slip planes and, moreover, the Peierls barrier actually relates to the core transformations. Hence, we follow the suggestion of Edagawa et al [36] who introduced the notion of the Peierls potential, V (x, y) , that is a function of two variables, x and y, which represent the position of the intersection of the dislocation line with the {111} plane perpendicular to the corresponding 〈111〉 slip direction. The transition of the screw dislocation between two low-energy sites at 0 K is then regarded as a motion along a minimum energy path, described by a curvilinear coordinate !…”

Section: Mesoscopic Dislocation Models Of Kink-pair Formationmentioning

confidence: 99%

“…This function, multiplied by a constant, can be regarded as a zeroth-order approximation of the Peierls potential and we choose it to be the same as in [36], where the two-dimensional Peierls potential was first introduced. It is a product of three sinusoidal functions and for the [111] direction of the dislocation line it reads The low-energy path connecting two minima of m(x, y) that we identify with the Peierls barrier always passes through the region in between neighboring minima and maxima of the Peierls potential.…”

Section: Symmetry Mapping Functionmentioning

confidence: 99%

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Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Gröger

Vítek

2008

Acta Materialia

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In this paper we develop a link between the atomic-level modeling of the glide of 1/2〈111〉 screw dislocations at 0 K and the thermally activated motion of these dislocations via nucleation of pairs of kinks. For this purpose, we introduce the concept of a hypothetical Peierls barrier, which reproduces all the aspects of the dislocation glide at 0 K resulting from the complex response to non-glide stresses and expressed in a compact form by the yield criteria advanced in Part II. To achieve this the barrier is dependent not only on the crystal symmetry and interatomic bonding but also on the applied stress tensor. Standard models are then employed to evaluate the activation enthalpy of kink-pairs formation, which is now also a function of the full applied stress tensor. The transition states theory links then this mechanism with the temperature and strain rate dependence of the yield stress.

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Section: Discussionmentioning

confidence: 99%

Section: Construction Of the Peierls Potential And The Peierls Barriermentioning

confidence: 99%

Section: Mesoscopic Dislocation Models Of Kink-pair Formationmentioning

confidence: 99%

Section: Symmetry Mapping Functionmentioning

confidence: 99%

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Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

Gröger

Vítek

2008

Acta Materialia

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“…Edagawa et al 19 suggested that the dislocation motion in TABLE I. Peierls stress ͑ P ͒ and core structure for a screw dislocation in Ta using the present multiscale approach, the FP-GFBC method, the EAM, and the modified generalized pseudopotential theory ͑MGPT͒.…”

mentioning

confidence: 99%

Effect of the local environment on the mobility of dislocations in refractory bcc metals: Concurrent multiscale approach

et al. 2008

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Using a concurrent multiscale approach we demonstrate that the local environment of transition-metal solutes in refractory bcc metals has a large effect on the mobility and slip paths of dislocation. The results reveal that solid solutes or nanoclusters of different geometries may lead to solid-solution hardening or softening, in agreement with experiment, including spontaneous dislocation glide and activation of new slip planes. The underlying electronic mechanism is the change in the anisotropy of the lattice resistance induced by solutes. DOI: 10.1103/PhysRevB.78.134102 PACS number͑s͒: 61.72.Lk, 71.15.Ϫm, 62.20.FϪ Solute atoms are ubiquitous in metals and play a key role in altering their mechanical properties ͑e.g., strength and ductility͒. Experimental studies during the past several decades indicate that solutes can give rise to both solid-solution hardening ͑SSH͒ and solid-solution softening ͑SSS͒.1,2 The origin of SSH/SSS is due to the interaction between dislocations and solutes and/or precipitates in materials. In most situations, the dislocation behavior is considerably different in the realistically dirty materials, where dislocation mobility can vary by several orders of magnitude. This significant influence induced by small amounts of solutes is of great practical importance to, for example, the bcc refractory metals ͑Nb, W, Ta, and Mo͒. These systems exhibit unique mechanical properties that make them attractive for structural applications at elevated temperatures. An inherent drawback limiting the use of these materials as structural components is their reduced low-temperature toughness, which in turn increases the propensity toward fracture. Thus, the challenge in design of advanced alloys is to combine strengthening and toughening phases with a better balance of properties.Continuum elasticity theory has provided considerable insight of SSS/SSH in terms of the size and elastic constants between the solute and host atoms. The correlation between the hardening rate and number of conduction electrons of transition-metal solutes, however, indicates a nonlinear chemical origin of the dislocation-solute interaction.3,4 In their pioneering work, Trinkle and Woodward 3 using the first-principles Greens function boundary condition ͑FP-GFBC͒ method, 5 demonstrated the transition-metal solutes can have a large effect on the dislocation core and hence the mobility. Nevertheless, understanding the physics of interactions of dislocations with nanoclusters remains a challenging problem.In this paper, we have developed a concurrent multiscale approach, which opens the door to studying the important problem of chemistry effect on the mechanical properties of metals. This approach treats correctly the long-range elastic field of the dislocation and describes the solute-host atomic interaction in the core region accurately. We have applied this approach to the Ta-W alloys, two prototype bcc metals, because ͑1͒ experiments have shown the dual nature of W: the addition of 2.5-10.0 wt.% W in Ta increases the str...

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