Screw dislocation interaction with irradiation defect-loops in α-iron: evaluation of cross-slip effect using dislocation dynamics simulations

2018 ◽  
Vol 26 (5) ◽  
pp. 055009 ◽  
Author(s):  
Y Li ◽  
C Robertson ◽  
M Shukeir ◽  
L Dupuy
Keyword(s):  
Screw Dislocation ◽  
Cross Slip ◽  
Dislocation Dynamics ◽  
Slip Effect ◽  
Dislocation Interaction ◽  
Irradiation Defect ◽  
Dynamics Simulations

Determination of Dislocation Interaction Strengths Using Discrete Dislocation Dynamics of Curved Dislocations

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Alankar Alankar ◽  
Ioannis N. Mastorakos ◽  
David P. Field ◽  
Hussein M. Zbib
Keyword(s):  
Shear Stress ◽  
Pure Aluminum ◽  
Dislocation Dynamics ◽  
Dislocation Interaction ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Junction Formation ◽  
Latent Hardening ◽  
Dynamics Simulations

In latent interactions of dislocations, junction formation is one of the most important phenomena that contribute to the evolution of strength. In this work, the latent hardening coefficients for pure aluminum are estimated using 3D multiscale dislocation dynamics program (MDDP). Three well-known junction configurations, namely, the Hirth lock, the glissile junction, and the Lomer lock, are studied using 3D discrete dislocation dynamics simulations. The evolution of strength is discussed as a function of the resolved shear stress (RSS) and the number of junctions for the three junctions investigated. Hirth lock and Lomer lock are found to be the weakest and strongest junctions, respectively. Collinear reaction of dislocations does not form a junction but causes a higher strength than a Lomer lock. Quantitative and qualitative results are compared with those found in the literature.

Molecular dynamics simulation of screw dislocation interaction with stacking fault tetrahedron in face-centered cubic Cu

2007 ◽  
Vol 22 (10) ◽  
pp. 2758-2769 ◽  
Author(s):  
Hyon-Jee Lee ◽  
Jae-Hyeok Shim ◽  
Brian D. Wirth
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Stacking Fault ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Dislocation Interaction ◽  
Complete Absorption ◽  
Stacking Fault Tetrahedron ◽  
Face Centered ◽  
Dynamics Simulations

The interaction of a gliding screw dislocation with stacking fault tetrahedron (SFT) in face-centered cubic (fcc) copper (Cu) was studied using molecular dynamics simulations. Upon intersection, the screw dislocation spontaneously cross slips on the SFT face. One of the cross-slipped Shockley partials glides toward the SFT base, partially absorbing the SFT. At low applied stress, partial absorption produces a superjog, with detachment of the trailing Shockley partial via an Orowan process. This leaves a small perfect SFT and a truncated base behind, which subsequently form a sheared SFT with a pair of opposite sense ledges. At higher applied shear stress, the ledges can self-heal by gliding toward an SFT apex and transform the sheared SFT into a perfect SFT. However, complete absorption or collapse of an SFT (or sheared SFT) by a moving screw dislocation is not observed. These observations provide insights into defect-free channel formation in deformed irradiated Cu.

scholarly journals Temperature and composition dependent screw dislocation mobility in austenitic stainless steels from large-scale molecular dynamics

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Kevin Chu ◽  
Michael E. Foster ◽  
Ryan B. Sills ◽  
Xiaowang Zhou ◽  
Ting Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Drag Coefficient ◽  
Screw Dislocation ◽  
Stainless Steels ◽  
Threshold Stress ◽  
Elevated Temperatures ◽  
Austenitic Stainless Steels ◽  
Dislocation Dynamics ◽  
Dislocation Mobility ◽  
Dynamics Simulations

AbstractExtensive molecular dynamics simulations are performed to determine screw dislocation mobility in austenitic Fe0.7NixCr0.3-x stainless steels as a function of temperature ranging from 100 to 1300 K, resolved shear stress from 30 to 140 MPa, and Ni composition from 0.0 to 30.0 at%. These mobility data are fitted to a linear mobility law with a nonzero stress offset, referred to as the threshold stress. We find that both the linear drag coefficient and the threshold stress increase with Ni composition. The drag coefficient increases with temperature, whereas the threshold stress decreases with temperature. Based on these calculations, we determine fitting functions for the linear solute drag coefficient as a function of temperature and composition. The mobility laws determined in this study may serve to inform dislocation dynamics simulations pertinent to dislocation network evolution at elevated temperatures for a wide composition range of austenitic stainless steels.

Plastic Ploughing of a Sinusoidal Asperity on a Rough Surface

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
H. Song ◽  
R. J. Dikken ◽  
L. Nicola ◽  
E. Van der Giessen
Keyword(s):  
Friction Stress ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Unit Process ◽  
Contact Models ◽  
Self Similar ◽  
Dynamics Simulations ◽  
Micrometer Scale ◽  
Edge Dislocations ◽  
Flat Contact

Part of the friction between two rough surfaces is due to the interlocking between asperities on opposite surfaces. In order for the surfaces to slide relative to each other, these interlocking asperities have to deform plastically. Here, we study the unit process of plastic ploughing of a single micrometer-scale asperity by means of two-dimensional dislocation dynamics simulations. Plastic deformation is described through the generation, motion, and annihilation of edge dislocations inside the asperity as well as in the subsurface. We find that the force required to plough an asperity at different ploughing depths follows a Gaussian distribution. For self-similar asperities, the friction stress is found to increase with the inverse of size. Comparison of the friction stress is made with other two contact models to show that interlocking asperities that are larger than ∼2 μm are easier to shear off plastically than asperities with a flat contact.

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