Non-planar dislocations: 3D models and thermally-activated glide processes

Ngan, A.H.W.

doi:10.1016/j.msea.2005.03.049

Cited by 4 publications

(2 citation statements)

References 27 publications

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“…The implications for kink nucleation have been examined in detail for Fe potentials that predict a polarized core structure [5][6][7]. For instance, Wen and Ngan studied the activation pathways of kink-nucleation in Fe with an empirical potential [8] and found that the most energetically favored process predicted the correct activation energy at zero stress.…”

Section: Introductionmentioning

confidence: 99%

Screw dislocation mobility in BCC metals: the role of the compact core on double-kink nucleation

Gordon¹,

Neeraj²,

Li³

et al. 2010

Modelling Simul. Mater. Sci. Eng.

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In this work, we examine the kink-nucleation process in BCC screw dislocations using atomistic simulation and transition pathway analysis, with a particular focus on the compact core structure. We observe the existence of a threshold stress, which results in an abrupt change in the minimum energy path of the kink-nucleation process, and hence, a discontinuity in the activation energy versus stress for the process. The magnitude of the discontinuity is found to be related to the degree of metastability of an intermediate split-core structure. This feature appears to be a direct consequence of the so-called 'camel-hump' nature of the Peierls potential, which manifests itself in the existence of a metastable, intermediate split-core structure. The effect is observed in a number of empirical EAM potentials, including Fe, Ta, V, Nb and Mo, suggesting a generality to the observations.

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Section: Introductionmentioning

confidence: 99%

Screw dislocation mobility in BCC metals: the role of the compact core on double-kink nucleation

Gordon¹,

Neeraj²,

Li³

et al. 2010

Modelling Simul. Mater. Sci. Eng.

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“…The transition state pathways are explored using the free-end NEB method [20], a variant of the methods proposed by Henkelman and Jonsson [21][22][23]. The NEB method has found widespread application in exploring reaction transition pathways, and has been applied to study thermally activated processes in stressed mechanical systems, including dislocation emission from cracktips [24], brittle cleavage [25,26] and screw dislocation motion [27,28]. The original formulation of the method can become inefficient in systems where the transition from the initial to the final state results in a large release of stored elastic energy.…”

Section: Simulation Methodsmentioning

confidence: 99%

The effect of heterogeneities on dislocation nucleation barriers from cracktips in α-Fe

Gordon

Neeraj

Luton

2009

Modelling Simul. Mater. Sci. Eng.

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In this work, we employ atomistic models to examine how heterogeneities at or near a cracktip influence the barriers to dislocation nucleation. We conceive of two simple scenarios designed to probe spatial and chemical effects. In the first example, we probe the effect of surface steps along the crackfront. In the second case, substitutional solutes are introduced on the emission slip plane at and in front of the crackfront. The impact of these heterogeneities is assessed by comparing the activation energy barriers for dislocation nucleation with a cracktip of the same orientation and loading without the heterogeneities present. The impact on the activation energies for emission is shown to be a function of the heterogeneity density and the volume of activation required at a given stress intensity.

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Improved Peierls-Nabarro model for asymmetric nonplanar 1/2<110]{111} screw dislocations in L10 alloys

Huang

2021

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Non-planar dislocations: 3D models and thermally-activated glide processes

Cited by 4 publications

References 27 publications

Screw dislocation mobility in BCC metals: the role of the compact core on double-kink nucleation

Screw dislocation mobility in BCC metals: the role of the compact core on double-kink nucleation

The effect of heterogeneities on dislocation nucleation barriers from cracktips in α-Fe

Improved Peierls-Nabarro model for asymmetric nonplanar 1/2<110]{111} screw dislocations in L10 alloys

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