Dynamic aspects of dislocation motion: atomistic simulations

Bitzek, Erik; Gumbsch, Peter

doi:10.1016/j.msea.2005.03.047

Cited by 88 publications

(65 citation statements)

References 10 publications

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“…(1) can significantly overestimate the strength of voids as obstacles to dislocation motion [3,7,36]. While Bitzek and Gumbsch [7] have shown that inertial effects are one factor that reduces s c , our results suggest that image forces also contribute to the reduction in s c , compared to Eq. (1).…”

Section: Void Strength Modelcontrasting

confidence: 57%

“…Several studies of the interaction of dislocations and voids have been carried out by means of molecular dynamics (MD) [3][4][5][6][7][8]. These studies have provided tremendous insight into bypass mechanisms at the atomic scale, such as glide [3], climb [4], and inertial effects [7].…”

Section: Introductionmentioning

confidence: 99%

“…These studies have provided tremendous insight into bypass mechanisms at the atomic scale, such as glide [3], climb [4], and inertial effects [7]. However, void sizes directly accessible to MD are typically in the range of 1-6 nm, whereas corresponding void sizes found in crystalline materials commonly range from tens of nanometers to microns [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Capturing the effects of free surfaces on void strengthening with dislocation dynamics

2015

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a b s t r a c tVoid strengthening in crystalline materials refers to the increase in yield stress due to the impediment of dislocation motion by voids. Dislocation dynamics (DD) is a modeling method well suited to capture the physics, length scales, and time scales associated with void strengthening. However, previous DD simulation of dislocation-void interactions have been unable to accurately account for the strong image forces acting on the dislocation due to the void's free surface. In this article, we employ a finite-element-based DD method to determine the obstacle strength of voids, defined as the critical resolved shear stress for a dislocation to glide past an array of voids. Our results demonstrate that the attractive image forces between the dislocation and free surface significantly reduce the obstacle strength of voids. Effects of surface mobility and stress concentrations around the void are also explored and are shown to have minimal effect on the critical stress. Finally, a new model relating void size and spacing to obstacle strength is proposed.

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Section: Void Strength Modelcontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Capturing the effects of free surfaces on void strengthening with dislocation dynamics

2015

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“…Like the partial dislocation cross-slip, this "stimulated emission" of partial or full dislocation loops on the inclined planes is also observed using slightly different set-ups (21) . It is interesting to note that the stimulated emission can be suppressed by setting all atomic velocities to zero shortly before contact between dislocation and crack (21) , thus significantly reducing the dislocation velocity and inertia (25) .…”

Section: Dislocations Of Class IImentioning

confidence: 99%

Atomistic Simulations of Dislocation - Crack Interaction

Bitzek

Gumbsch

2008

JMMP

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The interaction of dislocations with a static mode I crack is studied by large scale molecular dynamics simulations. The model consists of a blunted [001](110) crack in nickel, to which after relaxation at K < K Ic the displacement field of a dislocation is added. The response of the system is monitored during its evolution in the microcanonical ensemble. The simulations allowed to identify different characteristic processes during the interaction of the impinging dislocation with the crack. In particular, stimulated dislocation emission and cross slip processes are observed to be important for the development of a plastic zone.

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“…16 Traditionally, approaches to dislocation motion, mainly relevant to the low-velocity phonon-dragcontrolled regime, 17 rely on a simple overdamped mobility law and include inertia (when needed) by means of a Newtonian-like dislocation mass factor. 18,19 However, such phenomenological approaches (including relativistic ones 20 ) have been ruled out by phase-field calculations when acceleration is fast, and when the velocity becomes a sizable fraction of the shear wave speed. 21 As has long been recognized, 22 the key to dislocation inertia resides in the phenomenon of radiation reaction.…”

Section: Introductionmentioning

confidence: 99%

Equation of motion and subsonic-transonic transitions of rectilinear edge dislocations: A collective-variable approach

Pellegrini

2014

Phys. Rev. B

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A theoretical framework is proposed to derive a dynamic equation motion for rectilinear dislocations within isotropic continuum elastodynamics. The theory relies on a recent dynamic extension of the Peierls-Nabarro equation, so as to account for core-width generalized stacking-fault energy effects. The degrees of freedom of the solution of the latter equation are reduced by means of the collective-variable method, well-known in soliton theory, which we reformulate in a way suitable to the problem at hand. Through these means, two coupled governing equations for the dislocation position and core width are obtained, which are combined into one single complex-valued equation of motion, of compact form. The latter equation embodies the history dependence of dislocation inertia. It is employed to investigate the motion of an edge dislocation under uniform time-dependent loading, with focus on the subsonic/transonic transition. Except in the steady-state supersonic range of velocities-which the equation does not address-our results are in good agreement with atomistic simulations on tungsten. In particular, we provide an explanation for the transition, showing that it is governed by a loading-dependent dynamic critical stress. The transition has the character of a delayed bifurcation. Moreover, various quantitative predictions are made, that could be tested in atomistic simulations. Overall, this work demonstrates the crucial role played by core-width variations in dynamic dislocation motion.

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Dynamic aspects of dislocation motion: atomistic simulations

Cited by 88 publications

References 10 publications

Capturing the effects of free surfaces on void strengthening with dislocation dynamics

Capturing the effects of free surfaces on void strengthening with dislocation dynamics

Atomistic Simulations of Dislocation - Crack Interaction

Equation of motion and subsonic-transonic transitions of rectilinear edge dislocations: A collective-variable approach

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