THE MOBILITY OF THE EDGE DISLOCATION IN METAL: A MOLECULAR DYNAMICS SIMULATION

2011 ◽  
Vol 25 (25) ◽  
pp. 3315-3324
Author(s):  
XIYUAN YANG
Keyword(s):  
Molecular Dynamics ◽  
Relaxation Time ◽  
Edge Dislocation ◽  
Initial Period ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Embedded Atom ◽  
Partial Dislocations ◽  
Dislocation Movement ◽  
Straight Lines

In this paper, we use molecular dynamics (MD) simulations and a modified analytic embedded-atom method to investigate the edge dislocation movement without imposed strain at 0 K. The obtained results indicate that the straight lines of the partial dislocations always preserve their original shapes and are parallel to each other during the simulation process. According to the energy of each atom, the positions of both partial dislocation cores are determined. Then the velocities in the period of the relaxation process are investigated in detail. The MD simulations reveal that the MD relaxation time dependence of the edge dislocation mobility is divided into two parts. First, during the initial period ranging from 0 to 6 ps, the relative velocity of the dislocation movement lineally increases with the incremental relaxation time. Second, in the latter period from 6 ps to the end of the simulated process the velocity decreases exponentially as the MD simulation time evolves.

Choosing Appropriate Interatomic Potentials for Nanometric Molecular Dynamics (MD) Simulations

2016 ◽  
Vol 686 ◽  
pp. 194-199
Author(s):  
Akinjide O. Oluwajobi ◽  
Xun Chen
Keyword(s):  
Molecular Dynamics ◽  
Diamond Tool ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Interatomic Potentials ◽  
Embedded Atom ◽  
Pair Potentials ◽  
Empirical Potentials ◽  
Nanometric Machining ◽  
Cutting Processes

There is a need to choose appropriate interatomic empirical potentials for the molecular dynamics (MD) simulation of nanomachining, so as to represent chip formation and other cutting processes reliably. Popularly applied potentials namely; Lennard-Jones (LJ), Morse, Embedded Atom Method (EAM) and Tersoff were employed in the molecular dynamics simulation of nanometric machining of copper workpiece with diamond tool. The EAM potentials were used for the modelling of the copper-copper atom interactions. The pairs of EAM-Morse and EAM-LJ were used for the workpiece-tool (copper-diamond) atomic interface. The Tersoff potential was used for the carbon-carbon interactions in the diamond tool. Multi-pass simulations were carried out and it was observed that the EAM-LJ and the EAM-Morse pair potentials with the tool modelled as deformable with Tersoff potential were best suitable for the simulation. The former exhibit the lowest cutting forces and the latter has the lowest potential energy.

Stability of Hollow Nanospheres: A Molecular Dynamics Study

2007 ◽  
Vol 129 ◽  
pp. 125-130 ◽  
Author(s):  
Alexander V. Evteev ◽  
Elena V. Levchenko ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Molecular Dynamics ◽  
Defect Formation ◽  
External Surface ◽  
Vacancy Concentration ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Hollow Nanospheres ◽  
Shockley Partial ◽  
Embedded Atom ◽  
Partial Dislocations

Molecular dynamics simulation using the embedded-atom method is applied to study defect formation and distribution in a hollow Pd nanosphere. It is established that besides vacancies, which can nucleate on the inner or external surfaces, at the external surface, other defects (Shockley partial dislocations, twins and stacking faults) form due to its significant reconstruction by means of a/6〈112〉 shears of atomic rows. The density of the defects on the external surface grows with decreasing nanoshell size. It is demonstrated that Shockley partial dislocations can act as vehicles for the transfer of material from the external surface to the inner surface of the nanoshell thus leading to shrinking. It is shown that the vacancy concentration is higher near both surfaces than in the bulk of the nanoshell.

scholarly journals SIZE-DEPENDENT ELASTIC PROPERTIES OF Ni NANOFILMS BY MOLECULAR DYNAMICS SIMULATION

2007 ◽  
Vol 14 (04) ◽  
pp. 661-665 ◽  
Author(s):  
ZHENYU YANG ◽  
YA-PU ZHAO
Keyword(s):  
Molecular Dynamics ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Surface Effects ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Surface Relaxation ◽  
Size Dependent ◽  
Embedded Atom

Size-dependent elastic properties of Ni nanofilms are investigated by molecular dynamics (MD) simulations with embedded atom method (EAM). The surface effects are considered by calculating the surface relaxation, surface energy, and surface stress. The Young's modulus and yield stress are obtained as functions of thickness and crystallographic orientation. It is shown that the surface relaxation has important effects on the the elastic properties at nanoscale. When the surface relaxation is outward, the Young's modulus decreases with the film thickness decreasing, and vice versa. The results also show that the yield stresses of the films increase with the films becoming thinner. With the thickness of the nanofilms decreasing, the surface effects on the elastic properties become dominant.

Molecular-Dynamics Simulation of the Initial Period of Cluster Deposition

2002 ◽  
Vol 749 ◽  
Author(s):  
K. Shintani ◽  
T. Nakajima ◽  
Y. Taniguchi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Initial Period ◽  
Equations Of Motion ◽  
Atomic Layer ◽  
Deposition Process ◽  
Dynamics Simulation ◽  
Soft Landing ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

ABSTRACTThe initial periods of deposition process of metal clusters in the soft-landing regime are investigated by the molecular-dynamics simulation. The embedded-atom method potential is adopted for calculation of the interaction between metallic atoms. The predictor-corrector method for second-order differential equations is employed for integration of the equations of motion. A simulation begins with equilibration of clusters and a substrate at a specified temperature. The lowest atomic layer in the substrate is fixed and the next few atomic layers are set to be velocity-scaling layers during the deposition process. The periodic boundary conditions are imposed in the horizontal directions. A single cluster with no velocity is deposited on the substrate. The simulations are performed at different temperatures of the clusters and substrate and for different sizes of clusters. How the morphological transition of the deposited nanostructures is affected by these parameters is discussed.

Study of Helium Bubble Induced Hardening in BCC-Fe by Molecular Dynamics Simulation

2019 ◽  
Vol 944 ◽  
pp. 378-386
Author(s):  
Li Xia Jia ◽  
Xin Fu He ◽  
Shi Wu ◽  
Dong Jie Wang ◽  
Han Cao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Edge Dislocation ◽  
Reasonable Agreement ◽  
Md Simulation ◽  
Md Simulations ◽  
Defect Size ◽  
Dynamics Simulation ◽  
Helium Bubble ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

The interaction between an moving edge dislocation and helium bubble was studied in BCC-Fe using Molecular dynamics（MD）simulation. Edge dislocation passed the bubble via cut mechanism. A step with a length of b is left on both sides of the bubble after dislocation left away. The influence of simulation temperature, defect size and He/V ratio in bubble on critical resolved shear stress (CRSS) for dislocation to shear bubble were investigated. The CRSS increases with increasing defect sizes, and decreases with increasing temperature. When He/V ratio is at the range of 0-1, CRSS depends weakly on the He/V ratio. The estimated obstacle strength of helium bubble based on MD simulations is acceptable and reasonable agreement with one deduced from the dispersion barrier-hardening model applied to experimental results.

Simulation of Dislocation Relaxation in FCC Metals

2006 ◽  
Vol 978 ◽  
Author(s):  
Yoshiaki Kogure ◽  
Kei Sakieda ◽  
Toshio Kosugi ◽  
Tadatoshi Nozaki
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Potential Energy ◽  
Edge Dislocation ◽  
Dislocation Motion ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Fcc Metals ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

Abstract Motion of edge dislocation in copper crystals is investigated by means of molecular dynamics simulation. The embedded atom method potential was used in the simulation. Configuration and motion of dislocations are graphically demonstrated in 3-dimentional model. Change of mean potential energy during the dislocation motion is also investigated.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

A Study on the Uniaxial Tension of FCC Metals at Nano Level Using MD

2008 ◽  
Vol 32 ◽  
pp. 255-258
Author(s):  
Bohayra Mortazavi ◽  
Akbar Afaghi Khatibi
Keyword(s):  
Molecular Dynamics ◽  
Uniaxial Tension ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Engineering Strain ◽  
Fcc Metals ◽  
Engineering Stress ◽  
Nano Science ◽  
Face Centered

Molecular Dynamics (MD) are now having orthodox means for simulation of matter in nano-scale. It can be regarded as an accurate alternative for experimental work in nano-science. In this paper, Molecular Dynamics simulation of uniaxial tension of some face centered cubic (FCC) metals (namely Au, Ag, Cu and Ni) at nano-level have been carried out. Sutton-Chen potential functions and velocity Verlet formulation of Noise-Hoover dynamic as well as periodic boundary conditions were applied. MD simulations at different loading rates and temperatures were conducted, and it was concluded that by increasing the temperature, maximum engineering stress decreases while engineering strain at failure is increasing. On the other hand, by increasing the loading rate both maximum engineering stress and strain at failure are increasing.

Graphene-Based Resonant Sensors for Detection of Ultra-Fine Nanoparticles: Molecular Dynamics and Nonlocal Elasticity Investigations

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550024 ◽  
Author(s):  
S. Kamal Jalali ◽  
M. Hassan Naei ◽  
Nicola Maria Pugno
Keyword(s):  
Molecular Dynamics ◽  
Nonlocal Elasticity ◽  
Md Simulations ◽  
Small Scale ◽  
Frequency Shifts ◽  
Resonant Sensors ◽  
Embedded Atom ◽  
Metal Metal ◽  
Spring System ◽  
Mass Spring

Application of single layered graphene sheets (SLGSs) as resonant sensors in detection of ultra-fine nanoparticles (NPs) is investigated via molecular dynamics (MD) and nonlocal elasticity approaches. To take into consideration the effect of geometric nonlinearity, nonlocality and atomic interactions between SLGSs and NPs, a nonlinear nonlocal plate model carrying an attached mass-spring system is introduced and a combination of pseudo-spectral (PS) and integral quadrature (IQ) methods is proposed to numerically determine the frequency shifts caused by the attached metal NPs. In MD simulations, interactions between carbon–carbon, metal–metal and metal–carbon atoms are described by adaptive intermolecular reactive empirical bond order (AIREBO) potential, embedded atom method (EAM), and Lennard–Jones (L–J) potential, respectively. Nonlocal small-scale parameter is calibrated by matching frequency shifts obtained by nonlocal and MD simulation approaches with same vibration amplitude. The influence of nonlinearity, nonlocality and distribution of attached NPs on frequency shifts and sensitivity of the SLGS sensors are discussed in detail.

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