scholarly journals Competitive B2 and B33 Nucleation during Solidification of Ni50Zr50 Alloy: Molecular Dynamics Simulation and Classical Nucleation Theory

2019 ◽  
Vol 123 (11) ◽  
pp. 6685-6692 ◽  
Author(s):  
Yang Sun ◽  
Feng Zhang ◽  
Huajing Song ◽  
Mikhail I. Mendelev ◽  
Cai-Zhuang Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory

scholarly journals Study of Effect of Size on Iron Nanoparticle by Molecular Dynamics Simulation

2021 ◽  
Vol 2 (3) ◽  
pp. 158-167
Author(s):  
Pham Huu Kien ◽  
Yiachu Khamphone ◽  
Giap Thi Thuy Trang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Iron Nanoparticles ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Iron Nanoparticle ◽  
Crystal Cluster ◽  
The Core ◽  
The One

We use the molecular dynamics simulation to study iron nanoparticles (NPs) consisting of 4000, 5000, 6000 atoms at temperatures of 300 and 900 K. The crystallization and microstructure were analyzed through the pair radial distribution function (PRDF), the potential energy per atom, the distribution of atom types and dynamical local structure parameters <fx>, where x is the bcc, ico or 14. The simulation indicated that amorphous NP contains a large number of ico-type atoms that play a role in preventing the crystallization. Amorphous NP is crystallized through transformations of f14 > 0 and fbcc = 0 type to bcc-type atoms when it is annealed at 900 K upon 40 ns. The growth of crystal clusters happens parallel with changing its microstructure. The behavior of the crystal cluster resembles the nucleation process described by classical nucleation theory. Furthermore, we found that the amorphous NP has two parts: the core has the structure similar to the one of amorphous bulk, in while the surface structure is more porous amorphous. Unlike amorphous NP, the crystalline NP also has three parts: the core is the bcc, the next part the distorted bcc and the surface is amorphous. Amorphous and crystalline NPs have part core which has the structure not depend on size. Doi: 10.28991/HIJ-2021-02-03-01 Full Text: PDF

Molecular Dynamics Simulation of Nano Cluster-Seed Effects on Heterogeneous Nucleation

2009 ◽  
Author(s):  
Donguk Suh ◽  
Seung-chai Jung ◽  
Woong-sup Yoon
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Three Dimensional ◽  
Seed Mass ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Order Of Magnitude ◽  
Nano Cluster

A three-dimensional heterogeneous nucleation is simulated by classical molecular dynamics, where the Lennard-Jones gas and solid nano cluster-seed molecules have argon and aluminum properties, respectively. All dimensions of the wall are periodic and a soft core carrier gas within the system controls the temperature rise induced by latent heat of condensation. There are three shapes of cluster-seeds being cube, rod, and sphere, three classes of masses, and the simulation took place under nine supersaturation ratios, making a total of 81 calculations. An analysis of variance was performed under a three-way layout to analyze the cluster-seed and supersaturation ratio effects on the system. For supersaturation ratios above the critical value nucleation rates were evaluated, below growth rates, and overall liquefaction rates were each defined and calculated. Results show that the supersaturation ratio dominantly controls all rates, but seed characteristics are important for the growth of the largest cluster under the critical supersaturation ratio. Overall liquefaction increases subject to an escalation of supersaturation ratio and seed mass. However, the significance of the supersaturation ratio for overall liquefaction suggests that thermal diffusion is more dominant than mass interactions for this system. Homogeneous characteristics are also compared with the heterogeneous system to find that though nucleation may occur for an insufficient supersaturation ratio when a seed is within the system, the addition of a seed does not in fact facilitate the increase in rates of the phenomena at high supersaturation ratios. Finally a comparison with the classical nucleation theory asserts a 3 to 4 order of magnitude difference, which is within the lines of deviation when it comes to theory and molecular simulations.

A study to investigate phase transitions and nucleation kinetics of nickel and copper

2016 ◽  
Vol 30 (11) ◽  
pp. 1650129 ◽  
Author(s):  
F. A. Celik ◽  
A. K. Yildiz
Keyword(s):  
Molecular Dynamics ◽  
Orientational Order ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Structural Development ◽  
Nucleation Kinetics ◽  
Embedded Atom ◽  
Bond Orientational Order ◽  
Kinetics Of

In this study, we investigate the homogeneous nucleation kinetics of copper and nickel system during cooling process using molecular dynamics simulation (MDS). The calculation is carried out for a different number of atoms consisting of 500, 2048, 8788 and 13,500 based on embedded atom method (EAM). It is observed that the melting points for the both model increases with increasing the size of systems (i.e. the number of atoms) as expected from Parrinello and Rahman MD method. The interfacial free energies and critical nucleus radius of nickel and copper are also determined by molecular dynamics, and the results are consistent with the classical nucleation theory. The structural development and phase transformation are also determined from the radial distribution function (RDF) and local bond orientational order parameters (LBOO).

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Droplet Size ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
First Passage Time ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Critical Droplet

Homogeneous nucleation processes are characterized by the nucleation rate and the critical droplet size. Molecular dynamics simulation is applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. The results are compared with the classical nucleation theory (CNT) and the Laaksonen–Ford–Kulmala (LFK) model that introduces the size dependence of the specific surface energy. It is shown for the nucleation rate that the Yasuoka–Matsumoto method and the mean first passage time method lead to considerably differing results. Even more significant deviations are found between two other approaches to the critical droplet size, based on the maximum of the Gibbs free energy of droplet formation (Yasuoka–Matsumoto) and the supersaturation dependence of the nucleation rate (nucleation theorem). CNT is found to agree reasonably well with the simulation results, whereas LFK leads to large deviations at high temperatures.

Molecular Dynamics Simulation of Bubble Nucleation in Superheated Liquid

2010 ◽  
Author(s):  
Chao Liu ◽  
Xiaobo Wu ◽  
Hualing Zhang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Argon Atom ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Superheated Liquid ◽  
Classic Nucleation Theory

The bubble homogeneous nucleation in superheated liquid argon is studied by molecular dynamics simulation in NVT ensemble. L-J potential is adopted for the interaction of argon atom. The simulated particle numbers of argon atom is 10976. The non-dimensional size of simulated box is 27.8×27.8×27.8. The initial non-dimensional temperature and density are 0.4 and 0.51 separately. The results show that the bubble homogeneous nucleation is divided into the waiting process, the appearing process of numerous small bubble nucleuses and the aggregation process of small bubble nucleuses. By fitting simulated data, we find that the bubble nucleation rate is eight orders of magnitudes bigger than the result of classic nucleation theory. The bubble nucleation rate increases along with the increasing of density and superheated temperature, which agrees well with one of classic nucleation theory.

Molecular Dynamics Simulation of Nanocluster Formation in a Supersonic Nano Nozzle Fabricated by Anodizing the Aluminum

2013 ◽  
Vol 829 ◽  
pp. 813-817
Author(s):  
Mohammad Hossein Tanhai ◽  
Shahyar Saramad ◽  
Peyman Nayebi
Keyword(s):  
Molecular Dynamics ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Magic Numbers ◽  
Gas Flows ◽  
Macro Scale ◽  
Novel Method ◽  
Gas Expansion ◽  
Small Clusters

A molecular dynamics method has been developed and applied for simulation of a supersonic Ne gas expansion through a convergingdiverging nozzle. Although the classical nucleation theory is able to explain some physics of the nucleation processes, however, due to the physical inaccuracy of the classical nucleation theory for small clusters, molecular dynamic method is more usable for studying gas flows having clusters. Pressure, flow velocity, temperature were parameters that extracted by MD method along the central x-axis. The nucleation and condensation of the clusters and their transient and equilibrium behavior are other parameters that are investigated in this simulation. The results show that although with suitable conditions the formation of clusters in a nanonozzle is possible, but the size of clusters is much smaller than its counterpart in macro scale and clusters with especial magic numbers are formed. The proposed novel method for fabrication this kind of nanonozzle is multi-step anodizing of the aluminum. This nanonozzle which can be fabricated experimentally can be used in Ionized Cluster Beam Deposition (ICBD) method.

Molecular Dynamics Simulation of Three-Dimensional Heterogeneous Nucleation

2011 ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Three Dimensional ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Seed Growth ◽  
Thermodynamic Conditions

Nanoparticle growth based on three-dimensional heterogeneous nucleation was simulated by classical molecular dynamics. To collectively observe the effects of the dimension of seeds and thermodynamic conditions, seed size and system supersaturation ratio were the factors that were examined to see if they influenced the nucleation rates. Two stages were found to exist within the system, where the first stage is from the seed growth and the second from homogeneous nucleation. The Yasuoka-Matsumoto method was used to calculate the rates. The homogeneous nucleation characteristics coincided with the classical nucleation theory, but heterogeneous nucleation showed an irregular form, which at the current state cannot not be fully understood. Kinetic analysis was also performed to calculate the critical nucleus size and better understand the seed growth characteristics. All in all, the seed effects were insignificant to the overall nucleation characteristics for this system.

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