High-density liquid-like component facilitates plastic flow in a model amorphous silicon system

2003 ◽  
Vol 806 ◽  
Author(s):  
Michael J. Demkowicz ◽  
Ali S. Argon

ABSTRACTMolecular dynamics simulations show that plastic deformation behavior of model Stillinger-Weber amorphous Si is very sensitive to the density of the initial unstressed state. Low-density systems exhibit a pronounced yield phenomenon, strain softening, and a dramatic drop in pressure during deformation at constant volume. This behavior is explained by the interplay in every system of the prevailing solid-like and liquid-like components, with the latter being denser and more amenable to plastic flow.

RSC Advances ◽  
2016 ◽  
Vol 6 (99) ◽  
pp. 96824-96831 ◽  
Author(s):  
Junqin Shi ◽  
Yanan Zhang ◽  
Kun Sun ◽  
Liang Fang

The effect of a water film on the plastic deformation behavior and mechanism of monocrystalline copper are studied by molecular dynamics simulations.


Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5351
Author(s):  
Ahmed Tamer AlMotasem ◽  
Matthias Posselt ◽  
Tomas Polcar

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.


Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 750
Author(s):  
Xiaoyue Yang ◽  
Shuang Xu ◽  
Qingjia Chi

In this study, molecular dynamics simulations were performed to study the uniaxial compression deformation of bi-crystal magnesium nanopillars with a { 10 1 ¯ 2 } twin boundary (TB). The generation and evolution process of internal defects of magnesium nanopillars were analyzed in detail. Simulation results showed that the initial deformation mechanism was mainly caused by the migration of the twin boundary, and the transformation of TB into (basal/prismatic) B/P interface was observed. After that, basal slip as well as pyramidal slip nucleated during the plastic deformation process. Moreover, a competition mechanism between twin boundary migration and basal slip was found. Basal slip can inhibit the migration of the twin boundary, and { 10 1 ¯ 1 } ⟨ 10 1 ¯ 2 ⟩ twins appear at a certain high strain level ( ε = 0.104). In addition, Schmid factor (SF) analysis was conducted to understand the activations of deformation modes.


2011 ◽  
Vol 675-677 ◽  
pp. 949-951
Author(s):  
Li Ming Jiang ◽  
Ya Fang Guo

The mechanisms of low-temperature deformation around a crack tip in a hexagonally closed-packed (hcp) magnesium single crystal have been studied by molecular dynamics simulations. In our simulation a {1010} < 12 10 > model I (opening model) crack is selected. The results indicate that slip on the basal plane is activated due to the shear stress at the crack tip. Thus shear banding caused by a successive slip of the basal planes is the main deformation way for this type of crack.


2001 ◽  
Vol 703 ◽  
Author(s):  
Sebastian von Alfthan ◽  
Antti Kuronen ◽  
Kimmo Kaski

ABSTRACTEffect of a crystalline-amorphous interface on heat conduction has been studied using atom-istic simulations of a silicon system. System with amorphous silicon was created using the bond-switching Monte Carlo simulation method and heat conduction near room temperature was studied by molecular dynamics simulations of this system.


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