Dislocation nucleation from near surface void under static tensile stress in Cu

Abstract

We examine a possible mechanism for the formation of protrusions on a metallic surface held in a sufficiently high electric field in the presence of a near-surface void. By means of molecular dynamics simulations we show that the high tensile stress exerted on a Cu f110g surface with a near-surface void can promote the nucleation of dislocations on the void surface. These dislocations cause slip along f111g crystallographic planes leading to mass transport in the volume above the void. We find a linear correlation between the radius of the void and the maximum depth for the growth to occur. V

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

“…7b, where the stress concentrations increase the resolved shear stress by only 5-10% in most of the simulation domain. While these results suggest that including the effects due to stress concentrations are not significant in determining the strength of voids as obstacles to dislocation glide, we note that stress concentrations have been shown to play an important role in controlling dislocation evolution around voids such as dislocation nucleation [32,33] and cross-slip [26].…”

Interaction of dislocations with carbides in BCC Fe studied by molecular dynamics

“…Even though it has long been known on a general level that dislocations have a crucial effect on the mechanical properties of metals [1], the mechanisms by which impurities and precipitates interact with dislocations have started to be revealed only recently [2][3][4][5][6][7][8][9]. Dislocation movement and generation have also been found to play an important part in many different phenomena, pointing to the importance of knowledge on how they interact with obstacles in the material [10][11][12][13][14][15][16][17]. The key theoretical development enabling getting new scientific insight in this field has been the possibility to run multimillion-atom computer simulations that enable modelling both the dislocation and alloying elements or precipitates at realistic sizes.…”

From Field Emission to Vacuum Arc Ignition: A New Tool for Simulating Copper Vacuum Arcs

“…However, creating a full model of this life cycle requires the use of several simulation techniques to describe the different processes involved, which occur on different length-and time-scales. We attempt to do this with a combination of density functional theory, molecular dynamics, particle-in-cell (PIC) and hybrid simulation methods [16][17][18]. This paper focuses on modeling the initial plasma build-up in vacuum arcs using PIC.…”