On the atomic force microscopy characterization of void evolution in severely plastic deformed pure iron

Forouzanmehr, Nazanin; Nili-Ahmadabadi, N

doi:10.1088/1757-899x/63/1/012149

Cited by 3 publications

(1 citation statement)

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“…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]. Furthermore, MD, due to its limitations in the size of the computational domain, can frequently only be applied to modeling a single void in a periodic array of voids.…”

Section: Introductionmentioning

confidence: 99%

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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