On the mechanism of grain-boundary migration in metals: A molecular dynamics study

1991 ◽  
Vol 6 (11) ◽  
pp. 2291-2304 ◽  
Author(s):  
J.M. Rickman ◽  
S.R. Phillpot ◽  
D. Wolf ◽  
D.L. Woodraska ◽  
S. Yip
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Three Dimensional ◽  
Atomic Level ◽  
Dynamics Simulation ◽  
Grain Boundary Migration ◽  
Migration Process ◽  
Interparticle Bond ◽  
Simulation Cell

The migration of a (100) θ = 43.6°(Σ29) twist grain boundary is observed during the course of a molecular-dynamics simulation. The atomic-level details of the migration are investigated by determining the time dependence of the planar structure factor, a function of the planar interparticle bond angles, and the location of the center of a mass of planes near the grain boundary. It is found that a migration step consists of local bond rearrangements which, when the simulation cell is made large enough, produce domain-like structures in the migrating plane. Although no overall sliding is observed during migration, a local sliding of the planes near the migrating grain boundary accompanies the migration process. It is suggested that a three-dimensional cloud of thermally produced Frenkel-like point defects near the boundary accompanies, and facilitates, its migration.

Molecular Dynamics Simulation of Stress Induced Grain Boundary Migration during Nanoindentation Experiments

2004 ◽  
Vol 449-452 ◽  
pp. 89-92 ◽  
Author(s):  
Jang Hyuk Yoon ◽  
Seong Jin Kim ◽  
Ho Jang
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Boundary Plane ◽  
Dynamics Simulation ◽  
Geometric Feature ◽  
Grain Boundary Migration ◽  
Grain Boundary Plane ◽  
Diamond Indenter ◽  
Slip Planes

Molecular dynamics (MD) simulation was performed to study the stress induced grain boundary migration caused by the interaction of dislocations with a grain boundary. The simulation was carried out in a Ni block (295020 atoms) with a Σ = 5 (210) grain boundary and an embedded atom potential for Ni was used for the MD calculation. Stress was provided by indenting a diamond indenter and the interaction between Ni surface and diamond indenter was assumed to have a fully repulsive force to emulate a traction free surface. Results showed that the indentation nucleated perfect dislocations and the dislocations produced stacking faults in the form of a parallelepiped tube. The parallelepiped tube was comprised of four {111} slip planes and it contained two pairs of parallel dislocations with Shockley partials. The dislocations propagated along the parallelepiped slip planes and fully merged onto the Σ = 5 (210) grain boundary without emitting a dislocation on the other grain. The interaction of the dislocations with the grain boundary induced the migration of the grain boundary plane in the direction normal to the boundary plane and the migration continued as long as the successive dislocations merged onto the grain boundary plane. The detailed mechanism of the conservative motion of atoms at the grain boundary was associated with the geometric feature of the Σ = 5 (210) grain boundary.

Studying Motion of 〈100〉 Tilt Grain Boundaries Using Molecular Dynamics Simulation

2014 ◽  
Vol 1704 ◽  
Author(s):  
Shijing Lu ◽  
Donald W. Brenner
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Grain Boundary ◽  
Driving Force ◽  
Boundary Migration ◽  
Activation Energies ◽  
Dynamics Simulation ◽  
Grain Boundary Migration ◽  
Boundary Velocity ◽  
Rate Limiting

ABSTRACTIn the study of grain boundary migration of metallic materials using molecular dynamics simulation (MDS), grain boundary mobilities and activation energies are often found to be different from experimentally observed values. To reconcile the discrepancies, tremendous effort has been made to replicate experiment conditions in MDS, e.g.as low a driving force as possible, near zero grain boundary velocity. In the present study, we propose an analytic method that removes effects from non-physical conditions such as high driving force or high temperature. The analytic model presumes that two types of rate limiting events coexist during grain boundary migration. Kinetics parameters, such as activation energies, of the rare events are different and therefore should be modeled separately. Activation energies from this model are closer to experiment than previously reported values. Further, by analyzing the evolution of atomic structures, these two types of rate limiting events correspond to shear coupled migration and grain boundary sliding mechanisms, respectively.

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