Study of the Reactive Dynamics of Nanometric Metallic Multilayers Using Molecular Dynamics : The Al-Ni System

2012 ◽  
Vol 323-325 ◽  
pp. 89-94
Author(s):  
A. Linde ◽  
Olivier Politano ◽  
F. Baras
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Solid State Reaction ◽  
Diffusion Processes ◽  
Layer By Layer ◽  
Fixed Temperature ◽  
Embedded Atom ◽  
Specific Geometry ◽  
Reactive Dynamics ◽  
Embedded Atom Method Potential

A molecular dynamics study of a layered Ni-Al-Ni system is developed using an embedded atom method potential. The specific geometry is designed to model a Ni-Al nanometric metallic multilayer. The system is initially thermalized at the fixed temperature of 600 K. We first observe the interdiffusion of Ni and Al at the interfaces, which is followed by the spontaneous phase formation of B2-NiAl in the Al layer. The solid-state reaction is associated with a rapid system's heating which further enhances the diffusion processes. NiAl phase is organized in small regions separated by grain boundaries. This study confirms the hypothesis of a layer-by-layer development of the new phase. For longer times, the temperature is notably higher (> 1000 K) and the system may partly lose some its B2-NiAl microstructure in favor of the formation of Ni3Al in L12 configuration. This work shows the spontaneous development of a real exothermic solid-state reaction in metallic nanosystems mostly constituted by interfaces.

Study on the structural transition of CoNi nanoclusters using molecular dynamics simulations

2018 ◽  
Vol 32 (11) ◽  
pp. 1850133
Author(s):  
J. H. Xia ◽  
Xue-Mei Gao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structural Transition ◽  
Correction Function ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Analysis Technique ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential ◽  
Pair Analysis

In this work, the segregation and structural transitions of CoNi clusters, between 1500 and 300 K, have been investigated using molecular dynamics simulations with the embedded atom method potential. The radial distribution function was used to analyze the segregation during the cooling processes. It is found that Co atoms segregate to the inside and Ni atoms preferably to the surface during the cooling processes, the Co[Formula: see text]Ni[Formula: see text] cluster becomes a core–shell structure. We discuss the structural transition according to the pair-correction function and pair-analysis technique, and finally the liquid Co[Formula: see text]Ni[Formula: see text] crystallizes into the coexistence of hcp and fcc structure at 300 K. At the same time, it is found that the frozen structure of CoNi cluster is strongly related to the Co concentration.

Molecular Dynamics Prediction of the Influence of Composition on Thermotransport in Ni-Al Melts

2017 ◽  
Vol 12 ◽  
pp. 93-110 ◽  
Author(s):  
Tanvir Ahmed ◽  
Elena V. Levchenko ◽  
Alexander V. Evteev ◽  
Zi Kui Liu ◽  
William Yi Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Interatomic Potential ◽  
Diffusion In Solids ◽  
Recent Experimental Study ◽  
Heat Of Transport ◽  
Embedded Atom ◽  
Rich Liquid ◽  
Predicted Values ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential

The influence of composition on thermotransport (coupling between mass and heat transport) in Ni-Al melts is investigated by making use of equilibrium molecular dynamics simulations in conjunction with the Green-Kubo formalism. To describe interatomic interactions in Ni-Al melt models, we employ the embedded-atom method potential developed in [G.P. Purja Pun, Y. Mishin, Phil. Mag., 2009, 89, 3245]. It is demonstrated that the employed interatomic potential gives good agreement with the recent experimental study [E. Sondermann, F. Kargl, A. Meyer, Presented at the 12th International Conference on Diffusion in Solids and Liquids (DSL-2016), 26-30 June 2016, Split, Croatia] regarding the direction of thermotransport in Al-rich liquid Ni-Al alloys. Moreover, the predicted values of the reduced heat of transport (the quantity which explicitly characterizes both the magnitude and direction of thermotransport) in Ni-Al melts, reveal fairly weak composition dependence while being practically independent of temperature at all. Accordingly, in the presence of a temperature gradient, our simulation results for the models of liquid Ni25Al75, Ni50Al50 and Ni75Al25 alloys predict consistently Ni and Al to migrate to the cold and hot ends, respectively. Meanwhile, the highest value, about eV, of the reduced heat of transport is observed for Ni50Al50 alloy model and it slightly decreases towards Al-rich and Ni-rich compositions.

scholarly journals Effect of substrate temperature on quality of copper film catalyst substrate: A Molecular Dynamics Study

2017 ◽  
Vol 2 (2) ◽  
pp. 183 ◽  
Author(s):  
Rinaldo Marimpul
Keyword(s):  
Molecular Dynamics ◽  
Substrate Temperature ◽  
Film Growth ◽  
Copper Film ◽  
Deposition Process ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential

Copper film growth using thermal evaporation methods was studied using molecular dynamics simulations. The AlSiMgCuFe modified embedded atom method potential was used to describe interaction of Cu-Cu, Si-Si and Cu-Si atoms. Our results showed that the variations of substrate temperature affected crystal structure composition and surface roughness of the produced copper film catalyst substrate. In this study, we observed intermixing phenomenon after deposition process. The increasing of substrate temperature affected the increasing of the total silicon atoms had diffusion into copper film.

The oxidation of Nb 12 O 29 : electron microscopy of a solid-state reaction

1974 ◽  
Vol 339 (1619) ◽  
pp. 463-482 ◽  
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Solid State Reaction ◽  
Diffusion Processes ◽  
Block Structure ◽  
Lattice Structure ◽  
Mixed Valence ◽  
Oxidation Mechanism ◽  
Initial Oxidation ◽  
Temperature Oxidation

The two forms-monoclinic and orthorhombic - of the mixed valence Nb (IV, V) oxide Nb 12 O 29 oxidize at relatively low temperatures to two new modifications of Nb 2 O 5 . These, like the starting materials, are of the ‘block’ structure type, derived from the DO 9 structure by crystallo­graphic shear. Electron microscopy and electron diffraction show that the first distinct stage after complete oxidation is the formation of a super­-lattice structure derived from the structure of the original Nb 12 O 29 ; this undergoes internal reorganization leading, in the case of the monoclinic oxide, to the formation of a new modification of niobium pentoxide, Nb 10 O 25 , with a (3 x 3) 1 block structure. By using high resolution lattice imaging methods, the course of the initial oxidation step, the formation of the superlattice and its subsequent rearrangement have been traced in considerable detail. This low temperature oxidation process, which takes place with measurable speed at temperatures as low as 110 °C, clearly turns upon the diffusion of oxygen through the open channels of the DO 9 structure, and permits of a homogeneous solid state reaction involving only single unit jumps of atoms from original lattice sites into interstitial positions. At 440 °C and above, a second oxidation mechanism becomes competitive, involving reaction and rearrangement at the surface of the crystals. A reaction front then passes through the crystal by the co­-operative diffusion processes that are involved in the migration of crystal­lographic shear planes.

MD Simulation of Dislocation Dynamics in Copper Nanoparticles

2009 ◽  
Vol 1224 ◽  
Author(s):  
Yoshiaki Kogure ◽  
Toshio Kogugi ◽  
Tadatoshi Nozaki ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Boundary Condition ◽  
Md Simulation ◽  
Dislocation Dynamics ◽  
Embedded Atom Method ◽  
Dislocation Configuration ◽  
Embedded Atom ◽  
Model Crystal ◽  
Embedded Atom Method Potential ◽  
Dynamics Method

AbstractAtomistic configuration and motion of dislocation have been simulated by means of molecular dynamics method. The embedded atom method potential for copper is adopted in the simulation. Model crystal is a rectangular solid containing about 140,000 atoms. An edge dislocation is introduced along [112] direction near the center of model crystal, and the system is relaxed. After the dislocation configuration is stabilized, a shear stress is applied and released. Wavy motion of dislocation is developed on the Peierls valleys when the free boundary condition is adopted. Motion of pinned dislocation is also simulated.

Simulation of Mechanical Response in Nanoparticles

2012 ◽  
Vol 184 ◽  
pp. 301-306 ◽  
Author(s):  
Yoshiaki Kogure ◽  
T. Kosugi ◽  
T. Nozaki
Keyword(s):  
Molecular Dynamics ◽  
Mechanical Response ◽  
The Other ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Spherical Surfaces ◽  
Two Samples ◽  
Amorphous Structures ◽  
Embedded Atom Method Potential

Morphology and mechanical resonse of copper nanoparticles with defects have been simulated by means of molecular dynamics simulation. The embedded atom method potential for copper was used to express the interaction of atoms. Four types of model samples were prepared and about 37,000 atoms were contained in each sample. Two of them are cubic shape with {100} surfaces, in which vacancies or interstitials are introduced. The other two samples are once melted and solidified particles with nearly spherical surfaces. The atomic structure is controlled by cooling rate, and crystalline and amorphous structures are realized. Shear and tetragonal strains are applied to the samples and stress-strain relations for the samples are derived. Mechanical damping and internal friction were evaluated from the free decaying oscillations by releasing static strains.

Molecular-Dynamics Study of the Mechanical Properties of Metallic Nanowires

2002 ◽  
Vol 739 ◽  
Author(s):  
T. Nakajima ◽  
K. Shintani
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strain ◽  
Uniaxial Extension ◽  
Embedded Atom Method ◽  
Metallic Nanowires ◽  
Embedded Atom ◽  
Method Of Molecular Dynamics ◽  
Embedded Atom Method Potential ◽  
Thinning Process

ABSTRACTThe method of molecular-dynamics is employed to simulate and investigate the deformation of metallic nanowires under tensile strain. The interactions between metallic atoms are calculated by using the embedded-atom method potential. A model nanowire is preliminarily equilibrated at a specified temperature. Then, the uniform uniaxial extension of the nanowire is performed. The thinning process of a metallic nanowire is observed in the sequential snapshots of its morphological change.

scholarly journals Crystallization of FCC and BCC Liquid Metals Studied by Molecular Dynamics Simulation

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1532
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Andrey I. Bazlov
Keyword(s):  
Molecular Dynamics ◽  
Structural Changes ◽  
Liquid Metals ◽  
Crystal Nucleation ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Common Neighbor ◽  
Embedded Atom ◽  
Structure Observation ◽  
Embedded Atom Method Potential

The atomic structure variations on cooling, vitrification and crystallization processes in liquid metals face centered cubic (FCC) Cu are simulated in the present work in comparison with body centered cubic (BCC) Fe. The process is done on continuous cooling and isothermal annealing using a classical molecular-dynamics computer simulation procedure with an embedded-atom method potential at constant pressure. The structural changes are monitored with direct structure observation in the simulation cells containing from about 100 k to 1 M atoms. The crystallization process is analyzed under isothermal conditions by monitoring density and energy variation as a function of time. A common-neighbor cluster analysis is performed. The results of thermodynamic calculations on estimating the energy barrier for crystal nucleation and a critical nucleus size are compared with those obtained from simulation. The differences in crystallization of an FCC and a BCC metal are discussed.

Molecular-Dynamics Modelling of the Tensile Deformation of Helical Nanowires

2003 ◽  
Vol 778 ◽  
Author(s):  
K. Shintani ◽  
S. Kameoka
Keyword(s):  
Molecular Dynamics ◽  
Tensile Deformation ◽  
Axial Direction ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Helical Structures ◽  
Embedded Atom ◽  
Atom Chain ◽  
Au Nanowires ◽  
Embedded Atom Method Potential

AbstractDeformations of Au nanowires of helical structures under enforced elongation are addressed by the molecular-dynamics simulation. The embedded-atom method potential is employed for calculating the interaction between Au atoms. Model nanowires of the two kinds of helicities are prepared. Before elongation, a model nanowire is equilibrated at a specified temperature. Then, the Au atoms at one end of the nanowire are translationally moved in the axial direction. The simulation results show that a model nanowire can be elongated to form a single-atom chain of Au atoms under some circumstances.

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