Computer Simulation of Creation and Motion of Edge Dislocations in Face Centered Crystals

1994 ◽  
Vol 356 ◽  
Author(s):  
N. Tajima ◽  
T. Nozaki ◽  
T. Hirade ◽  
Y. Kogure ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Edge Dislocation ◽  
Embedded Atom ◽  
Small Crystals ◽  
Face Centered ◽  
Edge Dislocations

AbstractComplete and dissociated edge dislocations were created near the center of the surface (101) of aluminum small crystals whose surfaces are (111), (111), (101), (101). (121) and (121). Molecular dynamics with N-body embedded atom potentials were used. Higher stress is needed to create a complete edge dislocation than to create a dissociated dislocation.

Computer Simulation of Creation of Dislocations in Titanium Small Crystals

1993 ◽  
Vol 319 ◽  
Author(s):  
Junji Ida ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Single Crystal ◽  
Basal Plane ◽  
Embedded Atom ◽  
Small Crystals ◽  
Edge Dislocations

AbstractEdge dislocations were created on a basal plane (0001) in a small titanium single crystal whose surfases are (0001), (0001), (1010), (1010), (1210) and (1210) by use of n-body embedded atom potentials and molecular dynamics.

Simulation of Void Growth at High Strain-Rate

1998 ◽  
Vol 539 ◽  
Author(s):  
J. Belak ◽  
R. Minich
Keyword(s):  
Molecular Dynamics ◽  
Perfect Crystal ◽  
Dislocation Nucleation ◽  
Growth Exponent ◽  
Face Centered Cubic ◽  
Dynamics Modeling ◽  
Cubic Metals ◽  
Embedded Atom ◽  
Molecular Dynamics Modeling ◽  
Face Centered

AbstractThe dynamic fracture (spallation) of ductile metals is known to initiate through the nucleation and growth of microscopic voids. Here, we apply atomistic molecular dynamics modeling to the early growth of nanoscale (2nm radius) voids in face centered cubic metals using embedded atom potential models. The voids grow through anisotropic dislocation nucleation and emission into a cuboidal shape in agreement with experiment. The mechanism of this nucleation process is presented. The resulting viscous growth exponent at late times is about three times larger than expected from experiment for microscale voids, suggesting either a length scale dependence or a inadequacy of the molecular dynamics model such as the perfect crystal surrounding the void.

Towards a Virtual Laboratory for Grain Boundaries and Dislocations

2009 ◽  
Vol 1224 ◽  
Author(s):  
Sebastián Echeverri Restrepo ◽  
Barend J. Thijsse
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Systematic Study ◽  
Degrees Of Freedom ◽  
Minimum Energy ◽  
Local Symmetry ◽  
Virtual Laboratory ◽  
Face Centered Cubic ◽  
Face Centered ◽  
Edge Dislocations

AbstractIn order to perform a systematic study of the interaction between grain boundaries (GBs) and dislocations using molecular dynamics (MD), several tools need to be available. A combination of computational geometry and MD was used to build the foundations of what we call a virtual laboratory. First, an algorithm to generate GBs on face-centered cubic bicrystals was developed. Two crystals with different orientations are placed together. Then, by applying “microscopic” rigid body translations along the GB plane to one of the crystals and removing overlapping atoms, a set of initial configurations is sampled and a minimum energy configuration is found. Second, to classify the geometry of the GBs a local symmetry type (LST) describing the angular environment of each atom is calculated. It is found that for a given relaxed GB the number of atoms with different LSTs is not very large and that it is possible to find unique geometrical patterns in each GB. For instance, the LSTs of two GBs having the same “macroscopic” configuration but different “microscopic” degrees of freedom can be dissimilar: the configurations with higher GB energy tend to have a higher number of atoms with different LSTs. Third, edge dislocations are introduced into the bicrystals. We see that full edge dislocations split into Shockley partials. Finally, by loading the bicrystals with tensile stresses the edge dislocations are put into motion. Various examples of dislocation-GB interactions in Cu are presented.

Molecular Dynamics Simulation of the Solidification of Liquid Nickel Nanowires

2007 ◽  
Vol 121-123 ◽  
pp. 1053-1056
Author(s):  
Guo Rong Zhong ◽  
Qiu Ming Gao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Liquid Nickel ◽  
Cooling Rates ◽  
Final Structure ◽  
Embedded Atom ◽  
Nickel Nanowires ◽  
Face Centered

Molecular dynamics simulation of the solidification behavior of liquid nickel nanowires has been carried out based on the embedded atom potential with different cooling rates. The nanowires constructed with a face-centered cubic structure and a one-dimensional (1D) periodical boundary condition along the wire axis direction. It is found that the final structure of Ni nanowires strongly depend on the cooling rates during solidification from liquid. With decreasing cooling rates the final structure of the nanowires varies from amorphous to crystalline via helical multi-shelled structure.

MOLECULAR DYNAMICS SIMULATIONS OF STRUCTURAL PROPERTIES OF CuNi ALLOYS DURING THE COOLING PROCESS AT HIGH PRESSURE

2020 ◽  
Vol 65 (10) ◽  
pp. 10-17
Author(s):  
Thao Nguyen Thi ◽  
Giang Bui Thi Ha ◽  
Linh Tran Phan Thuy ◽  
Hop Nguyen Van ◽  
Chung Pham Do ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
High Pressure ◽  
Molecular Dynamics Simulations ◽  
Sudden Change ◽  
Face Centered Cubic ◽  
Cooling Process ◽  
Embedded Atom ◽  
The Face ◽  
Face Centered ◽  
Dynamics Simulations

Molecular dynamics simulations of Cu80Ni20 (Cu:Ni = 8:2) model with the size of 8788 atoms have been carried out to study the structure and mechanical behavior at high pressure of 45 GPa. The interactions between atoms of the system were calculated by the Quantum Sutton-Chen embedded-atom potentials. The crystallization has occurred during the cooling process with a cooling rate of 0.01 K\ps. The temperature range of the phase transition is determined based on the sudden change of atomic potential during the cooling process. There is also a sudden change in the number of individual atoms in the sample. At a temperature of 300 K, both Ni and Cu atoms are crystallized into the face-centered cubic (FCC) and the hexagonal close-packed (HCP) phases, respectively. The mechanical characteristics of the sample at 300 K were also analyzed in detail through the determination of elastic modulus, number of atoms, and void distribution during the tensile process.

Structure of a Dissociated Edge Dislocation in Copper

1999 ◽  
Vol 578 ◽  
Author(s):  
L. F. Perondi ◽  
P. Szelestey ◽  
K. Kaski
Keyword(s):  
Molecular Dynamics ◽  
Boundary Conditions ◽  
Edge Dislocation ◽  
Equilibrium Distance ◽  
Embedded Atom ◽  
Equilibrium Size ◽  
Atomic Interactions ◽  
Simulated System ◽  
Dynamics Simulations ◽  
Eam Potential

AbstractThe structure of a dissociated edge dislocation in copper is investigated. Attention is given to the structure of the Shockley partials and the equilibrium size of the fault ribbon. The studies are carried out through Molecular Dynamics simulations. The atomic interactions have been modelled through an Embedded Atom Model (EAM) potential. the implementation of which has been specially designed for this study. Our main results show that the equilibrium distance between partials is very sensitive to the type of boundary conditions imposed on the simulated system.

Computer Simulation of Creation of Dislocations in Copper Small Crystals

1993 ◽  
Vol 319 ◽  
Author(s):  
H. Tanaka ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Partial Dislocation ◽  
Stacking Fault ◽  
Shockley Partial Dislocation ◽  
Shockley Partial ◽  
Small Crystals ◽  
The Creation

AbstractDislocations were created near the center of the surface (101) of copper small crystals whose surfaces are (111), (111), (101), (101), (121), and (121) by use of n-body atom potentials and molecular dynamics. At first, a Heidenreich-Shockley partial dislocation was created., As the partial dislocation proceeds, the partial dislocation and the surface was connected with a stacking fault until the next Heidenreich-Shockley partial dislocation was created at the surface.Just before the creation of a partial dislocation the stress was the highest.

Molecular Dynamics Study on Interaction between Voids for Pure Aluminum

2010 ◽  
Vol 452-453 ◽  
pp. 845-848
Author(s):  
Shu Sheng Xu ◽  
Xiang Guo Zeng ◽  
Hua Yan Chen
Keyword(s):  
Molecular Dynamics ◽  
Pure Aluminum ◽  
Critical Distance ◽  
Atomic Scale ◽  
Embedded Atom Method ◽  
Face Centered Cubic ◽  
Embedded Atom ◽  
Modified Embedded Atom Method ◽  
Face Centered ◽  
The Impact

The voids in pure Aluminum always exit in the manufacturing process. The Modified Embedded Atom Method (MEAM) potential is employed in the molecular dynamics (MD) simulation at atomic scale to investigate the interaction between voids under the impact loading for pure Aluminum. The distance between the voids distributed along the loading orientation affects the failure mechanism seriously. The results show that there are 3 kinds of mechanisms with the change of the distance between voids: 1) coalescence takes place within a critical distance between voids under extra loading, 2) when the distance between voids reaches a certain value, each void cracks at 4 locations along with the slide direction <110> of face-centered cubic (fcc), respectively, 3) a stress shield zone appears when the ligament between the voids is at the size between the cases mentioned above, which brings out the phenomena that each of the voids cracks only at 2 locations, and no crack appeared at the stress shield zone.

Computer Simulation of Creation of Dislocations in Copper Small Crystals

1993 ◽  
Vol 319 ◽  
Author(s):  
H. Tanaka ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Partial Dislocation ◽  
Stacking Fault ◽  
Shockley Partial Dislocation ◽  
Shockley Partial ◽  
Small Crystals ◽  
The Creation

AbstractDislocations were created near the center of the surface (101) of copper small crystals whose surfaces are (111), (111), (101), (101), (121), and (121) by use of n-body atom potentials and molecular dynamics. At first, a Heidenreich-Shockley partial dislocation was created., As the partial dislocation proceeds, the partial dislocation and the surface was connected with a stacking fault until the next Heidenreich-Shockley partial dislocation was created at the surface.Just before the creation of a partial dislocation the stress was the highest.

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