Dislocation-Stacking Fault Tetrahedron Interactions in Cu

2002 ◽  
Vol 124 (3) ◽  
pp. 329-334 ◽  
Author(s):  
B. D. Wirth ◽  
V. V. Bulatov ◽  
T. Diaz de la Rubia
Keyword(s):  
Edge Dislocation ◽  
Interatomic Potential ◽  
High Energy ◽  
Dislocation Motion ◽  
Shear Localization ◽  
Stacking Fault ◽  
Dynamics Simulation ◽  
High Energy Particle ◽  
Face Centered Cubic ◽  
Stacking Fault Tetrahedra

In copper and other face centered cubic metals, high-energy particle irradiation produces hardening and shear localization. Post-irradiation microstructural examination in Cu reveals that irradiation has produced a high number density of nanometer sized stacking fault tetrahedra. The resultant irradiation hardening and shear localization is commonly attributed to the interaction between stacking fault tetrahedra and mobile dislocations, although the mechanism of this interaction is unknown. In this work, we present results from a molecular dynamics simulation study to characterize the motion and velocity of edge dislocations at high strain rate and the interaction and fate of the moving edge dislocation with stacking fault tetrahedra in Cu using an EAM interatomic potential. The results show that a perfect SFT acts as a hard obstacle for dislocation motion and, although the SFT is sheared by the dislocation passage, it remains largely intact. However, our simulations show that an overlapping, truncated SFT is absorbed by the passage of an edge dislocation, resulting in dislocation climb and the formation of a pair of less mobile super-jogs on the dislocation.

scholarly journals Atomistic Simulation of Dislocation-Defect Interactions in Cu

2000 ◽  
Vol 650 ◽  
Author(s):  
B. D. Wirth ◽  
V. V. Bulatov ◽  
T. Diaz de la Rubia
Keyword(s):  
Plastic Flow ◽  
Shear Localization ◽  
Stacking Fault ◽  
Dislocation Dynamics ◽  
Dynamics Simulation ◽  
Flow Localization ◽  
Plastic Flow Localization ◽  
Stacking Fault Tetrahedra ◽  
Dislocation Defect ◽  
Defect Interactions

ABSTRACTThe mechanisms of dislocation-defect interactions are of practical importance for developing quantitative structure-property relationships, mechanistic understanding of plastic flow localization and predictive models of mechanical behavior in metals under irradiation. In copper and other face centered cubic metals, high-energy particle irradiation produces hardening and shear localization. Post-irradiation microstructural examination in Cu reveals that irradiation has produced a high number density of nanometer sized stacking fault tetrahedra. Thus, the resultant irradiation hardening and shear localization is commonly attributed to the interaction between stacking fault tetrahedra and mobile dislocations, although the mechanism of this interaction is unknown. In this work, we present a comprehensive molecular dynamics simulation study that characterizes the interaction and fate of moving dislocations with stacking fault tetrahedra in Cu using an EAM interatomic potential. This work is intended to produce atomistic input into dislocation dynamics simulations of plastic flow localization in irradiated materials.

Interaction of Edge Dislocation With Stacking Fault Tetrahedron in Cu

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Jianfeng Jin ◽  
Hanchen Huang
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Edge Dislocation ◽  
Driving Force ◽  
Stacking Fault ◽  
Morphological Transformation ◽  
Atomic Mechanism ◽  
Stacking Fault Tetrahedra ◽  
Stacking Fault Tetrahedron ◽  
Thermodynamic Driving Force

This paper reports an anomaly in the yield strength of dislocation interacting with stacking fault tetrahedra (SFT) in Cu, reveals atomic mechanisms that are responsible for the anomaly, and further shows the thermodynamic driving force for the atomic mechanisms to prevail. Instead of monotonically increasing with the area of intersection cross-section, the yield strength first increases and then decreases with the area. The decrease, or the anomaly, is due to a change of atomic mechanism of the interactions—the SFT goes through a morphological transformation. The thermodynamic driving force for the transformation derives from the competition between the elastic energy of dislocations and the stacking fault energy.

Molecular Dynamics Simulation of Dislocation-Obstacle Interactions in Irradiated Materials

2007 ◽  
Vol 345-346 ◽  
pp. 947-950 ◽  
Author(s):  
Hyon Jee Lee ◽  
Jae Hyeok Shim ◽  
Brian D. Wirth
Keyword(s):  
Molecular Dynamics ◽  
Specific Interaction ◽  
Dislocation Motion ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Void Size ◽  
Dislocation Interaction ◽  
Stacking Fault Tetrahedron ◽  
Face Centered ◽  
Induced Defects

The interactions of a dislocation with commonly observed irradiation induced defects such as a stacking fault tetrahedron (SFT) and a void are studied using molecular dynamics (MD) simulation methods. The simulation of an SFT interacting with a dislocation in face centered cubic (FCC) copper (Cu) reveals that an SFT is a strong obstacle against a dislocation motion, with dislocation detachment often involving an Orowan like mechanism. The resulting SFT generally involves a shear step, although partial absorption is also observed in some specific interaction geometries. Dislocation interaction with a void has been studied in body centered cubic (BCC) molybdenum (Mo). The dislocation locally annihilates upon contact with the void and then re-nucleates on the void surface as the dislocation glides past the void. The interaction results in the simple shear of the void by one Burger’s vector. The obstacle strength of the void is measured using conjugate gradient molecular statics (MS) method as a function of void size. A large increase in the obstacle strength is observed for a void size greater than 3 nm in diameter.

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.

Mechanical Behavior of Polycrystalline Aluminum under Penetration with Extremely Large Loading Rates via Molecular Dynamics Simulation

2014 ◽  
Vol 566 ◽  
pp. 167-172 ◽  
Author(s):  
Chun Yi Wu ◽  
Yun Che Wang
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
High Velocity ◽  
Interatomic Potential ◽  
Thin Sheet ◽  
Tight Binding ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Thin Sheets ◽  
Polycrystalline Aluminum

In this study, polycrystalline aluminum nanoscale thin sheets are constructed by sputter deposition simulations with the molecular dynamics (MD) simulation. Subsequently, the penetration problem of a conical rigid projectile moving through the aluminum thin sheet is simulated by the MD technique. The MD simulations adopted the interatomic potential of a tight-binding type. During the deposition simulation, in order to include the ion-ion interactions, the pair-wise Moliere potential was adopted to model the interaction between working gas argon and deposited atoms. The as-deposited films did not show clear grain boundaries, but after thermal annealing, grains grow and form nanocrystalline structure with a grain size of 8 nm. The thin sheets consisted of the face-centered cubic phases of crystal unit cells, separated by grain boundaries. For the penetration simulations, four velocities were chosen 102, 103, 104 and 105 m/s. The first two velocities are called high velocity case and the rest two velocities are the hypervelocity case. Our results show that, as the penetration rate increases, more stresses are required to move the projectile through the Al film due to temperature effects from the high velocity to hypervelocity case. In addition, defects, such as dislocations, increase during the projectile penetration. In the high velocity case, the penetrated hole in the film may be recovered, but not in the hypervelocity case. The temperature difference increased in the hypervelocity case is significantly than that in the high velocity case.

FAULTED DEFECTS AND STACKING-FAULT ENERGY

1967 ◽  
Vol 45 (2) ◽  
pp. 1135-1146 ◽  
Author(s):  
L. M. Clarebrough ◽  
P. Humble ◽  
M. H. Loretto
Keyword(s):  
Direct Methods ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Face Centered Cubic ◽  
Dislocation Loops ◽  
Cubic Metals ◽  
The Third ◽  
Stacking Fault Tetrahedra ◽  
Dislocation Energy ◽  
Face Centered

Four direct methods of obtaining values of stacking-fault energy from observation of faulted defects in pure face-centered cubic metals are discussed. It is shown that there is essential agreement between the method based on the observation of threefold nodes and that based on the observation of triangular Frank dislocation loops and stacking-fault tetrahedra in deformed f.c.c. metals, in the range where both methods are applicable. On the other hand, it is shown that the third method, based on the collapse size of stacking-fault tetrahedra in quenched metals, cannot yield even an upper limit. New experimental results show that the fourth method, based on the annealing rate of faulted loops, is applicable only to metals of high stacking-fault energy and then only if jog nucleation and propagation are not rate controlling; for low stacking-fault energy metals, these factors, together with the dislocation energy, must be considered, and cannot be completely taken into account.

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