Combined influences of micro-pillar geometry and substrate constraint on microplastic behavior of compressed single-crystal micro-pillar: Two-dimensional discrete dislocation dynamics modeling

2009 ◽  
Vol 526 (1-2) ◽  
pp. 235-243 ◽  
Author(s):  
Chaojun Ouyang ◽  
Zhenhuan Li ◽  
Minsheng Huang ◽  
Lili Hu ◽  
Chuantao Hou
Keyword(s):  
Single Crystal ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Dynamics Modeling ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Substrate Constraint

Influence of Initial Defects on the Mechanical Properties of Single Crystal Copper: Discrete Dislocation Dynamics Study

2018 ◽  
Vol 913 ◽  
pp. 627-635
Author(s):  
Ming Yi Zhang ◽  
Min Zhong ◽  
Shuai Yuan ◽  
Jing Song Bai ◽  
Ping Li
Keyword(s):  
Dislocation Density ◽  
Single Crystal ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Dislocation Dynamics ◽  
Single Crystal Copper ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Stress Curve ◽  
Initial Dislocation Density

In this paper, three dimensional discrete dislocation dynamics method was used to quantitatively investigate the influence of initial defects on mechanical response of single crystal copper. Both the irradiation defects (interstitial loops) and random dislocation lines with different densities are considered. The simulation results demonstrate that the yield strength of single crystal copper is higher with higher initial dislocation density and higher interstitial loop density. Dislocation density increases quickly by nucleation and multiplication and microbands are formed during plastic deformation when only the random dislocation lines are initially considered. Characteristics of microbands show excellent agreement with experiment results. Dislocation multiplication is suppressed in the presence of interstitial loops, and junctions and locks between dislocations and interstitial loops are formed. Dislocation density evolution shows fluctuation accompanied with strain-stress curve fluctuation.

A discrete dislocation dynamics modeling for thermal fatigue of preferred oriented copper via patterns

2010 ◽  
Vol 63 (7) ◽  
pp. 788-791 ◽  
Author(s):  
Gyu Seok Kim ◽  
Marc C. Fivel ◽  
Hyo-Jong Lee ◽  
Chansun Shin ◽  
Heung Nam Han ◽  
...  
Keyword(s):  
Thermal Fatigue ◽  
Dislocation Dynamics ◽  
Dynamics Modeling ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Preferred Oriented

scholarly journals Dislocation climb in two-dimensional discrete dislocation dynamics

2012 ◽  
Vol 111 (10) ◽  
pp. 103522 ◽  
Author(s):  
Kamyar M. Davoudi ◽  
Lucia Nicola ◽  
Joost J. Vlassak
Keyword(s):  
Dislocation Climb ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation

scholarly journals Influence of Size on the Fractal Dimension of Dislocation Microstructure

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 478
Author(s):  
Yinan Cui ◽  
Nasr Ghoniem
Keyword(s):  
Fractal Dimension ◽  
Three Dimensional ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Transmission Electron ◽  
Dynamics Simulations ◽  
2D And 3D ◽  
Microscopy Images

Three-dimensional (3D) discrete dislocation dynamics simulations are used to analyze the size effect on the fractal dimension of two-dimensional (2D) and 3D dislocation microstructure. 2D dislocation structures are analyzed first, and the calculated fractal dimension ( n 2 ) is found to be consistent with experimental results gleaned from transmission electron microscopy images. The value of n 2 is found to be close to unity for sizes smaller than 300 nm, and increases to a saturation value of ≈1.8 for sizes above approximately 10 microns. It is discovered that reducing the sample size leads to a decrease in the fractal dimension because of the decrease in the likelihood of forming strong tangles at small scales. Dislocation ensembles are found to exist in a more isolated way at the nano- and micro-scales. Fractal analysis is carried out on 3D dislocation structures and the 3D fractal dimension ( n 3 ) is determined. The analysis here shows that ( n 3 ) is significantly smaller than ( n 2 + 1 ) of 2D projected dislocations in all considered sizes.

scholarly journals Influence of Excess Volumes Induced by Re and W on Dislocation Motion and Creep in Ni-Base Single Crystal Superalloys: A 3D Discrete Dislocation Dynamics Study

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 637 ◽  
Author(s):  
Siwen Gao ◽  
Zerong Yang ◽  
Maximilian Grabowski ◽  
Jutta Rogal ◽  
Ralf Drautz ◽  
...  
Keyword(s):  
Single Crystal ◽  
Excess Volume ◽  
Dislocation Motion ◽  
Excess Volumes ◽  
Dislocation Dynamics ◽  
Size Difference ◽  
Strengthening Effect ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Solute Atoms

A comprehensive 3D discrete dislocation dynamics model for Ni-base single crystal superalloys was used to investigate the influence of excess volumes induced by solute atoms Re and W on dislocation motion and creep under different tensile loads at 850 ° C. The solute atoms were distributed homogeneously only in γ matrix channels. Their excess volumes due to the size difference from the host Ni were calculated by density functional theory. The excess volume affected dislocation glide more strongly than dislocation climb. The relative positions of dislocations and solute atoms determined the magnitude of back stresses on the dislocation motion. Without diffusion of solute atoms, it was found that W with a larger excess volume had a stronger strengthening effect than Re. With increasing concentration of solute atoms, the creep resistance increased. However, a low external stress reduced the influence of different excess volumes and different concentrations on creep.

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