Investigation of Crystalline and Amorphous Forms of Aluminum and Its Alloys: Computational Modeling and Experiment

NANO ◽  
2018 ◽  
Vol 13 (03) ◽  
pp. 1850026
Author(s):  
Sergey Shityakov ◽  
Norbert Roewer ◽  
Carola Y. Förster ◽  
Hai T. Tran ◽  
Wenjun Cai ◽  
...  
Keyword(s):  
Metal Structure ◽  
Dislocation Nucleation ◽  
Al Alloys ◽  
Atomic Scale ◽  
Face Centered Cubic ◽  
Stress Strain ◽  
The Face ◽  
Tension And Compression ◽  
Face Centered ◽  
Dynamics Simulations

The purpose of this study is to investigate polycrystalline lattices of aluminum (Al) under the stress–strain conditions in all-atom molecular dynamics simulations and Al alloys using X-ray diffraction. Isothermal uniaxial tension and compression of these polycrystalline lattices showed no dislocation nucleation peaks, which correspond only to the Al monocrystal form. The best tensile and compressive resistance characteristics were observed for a material with the highest grain number ([Formula: see text]) due to the significant reduction of the face-centered cubic lattice in the metal structure. This process is mainly driven by the gradual elevation of the system’s kinetic energy. In the experiment, the amorphous Al alloys with higher manganese composition (20.5%) were investigated, matching the simulated amorphous structures. Overall, the results suggest that the increase in number of grains in Al lattices diminishes the stress–strain impact due to a more disordered atomic-scale (amorphous) metal composition.

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.

Prediction of metastable phase formation in an immiscible Cu–Cr system from interatomic potential and ab initio calculation

2003 ◽  
Vol 18 (10) ◽  
pp. 2300-2303 ◽  
Author(s):  
H. R. Gong ◽  
L. T. Kong ◽  
B. X. Liu
Keyword(s):  
Ab Initio ◽  
Interatomic Potential ◽  
Metastable Phase ◽  
The Body ◽  
Face Centered Cubic ◽  
The Face ◽  
Bcc Structure ◽  
Face Centered ◽  
Dynamics Simulations ◽  
Cr System

Ab initio calculation was performed to predict the structures, lattice constants, and cohesive energies of metastable Cu75Cr25 and Cu50Cr50 phases. An n-body Cu–Cr potential was derived through fitting to some ab initio calculated results and was capable of reproducing some intrinsic properties of the Cu–Cr system. Based on the derived potential, molecular dynamics simulations predicted that for a Cu100−xCrx alloy, the face-centered-cubic structure is more stable than the body-centered-cubic (bcc) one when 0 ≤ x ≤ 25, while the bcc structure becomes energetically favored when 25 < x ≤ 100. Interestingly, the predictions match well with the experimental observations.

Argon Thermal Conductivity by Anharmonic Lattice Dynamics Calculations

2008 ◽  
Author(s):  
J. E. Turney ◽  
A. J. H. McGaughey ◽  
C. H. Amon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Lattice Dynamics ◽  
Mode Shapes ◽  
Face Centered Cubic ◽  
Phonon Modes ◽  
Anharmonic Lattice ◽  
The Face ◽  
Face Centered ◽  
Dynamics Simulations

Lattice dynamics calculations are used to investigate thermal transport in the face-centered cubic Lennard-Jones (LJ) argon crystal between temperatures of 20 and 80 K. First, quasi-harmonic lattice dynamics calculations are used to find the frequencies and mode shapes of non-interacting phonons [1]. This information is then used as input for anharmonic lattice dynamics calculations. Anharmonic lattice dynamics is a means of computing the frequency shift and lifetime of each phonon mode due to interactions with other phonons [2]. The phonon frequencies, group velocities, and lifetimes, determined with the lattice dynamics methods, are then used to compute the thermal conductivity. The thermal conductivities predicted by the lattice dynamics methods are compared to predictions from molecular dynamics simulations. The two methods are found to agree well at low temperature but diverge at higher temperatures (i.e., near the melting point). The properties of individual phonon modes are used to identify the modes that dominate thermal transport.

Phase transition and dislocation nucleation in Cu–Nb layered composites during physical vapor deposition

2008 ◽  
Vol 23 (4) ◽  
pp. 1009-1014 ◽  
Author(s):  
Jian Wang ◽  
Richard G. Hoagland ◽  
Amit Misra
Keyword(s):  
Phase Transition ◽  
Physical Vapor Deposition ◽  
Dislocation Nucleation ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Layered Composites ◽  
Partial Dislocations ◽  
Deposition Parameters ◽  
Face Centered ◽  
Dynamics Simulations

Using classical molecular dynamics simulations, we have investigated the growth of {111} Cu on Nb {110} surface. Our results reveal that the deposited Cu layer initially grows as body-centered cubic (bcc) and Vernier misfits are observed in the interface of bcc Cu and bcc Nb. As it continues to grow, the bcc Cu {110} transforms into face-centered cubic (fcc) Cu {111}. The phase transition starts after the bcc Cu layer has accumulated about 3 monolayers and is finished depending on deposition parameters. Nuclei of fcc Cu {111} form in the top surface of Cu and grow in plane and toward the interface. Partial dislocations in the fcc Cu layer nucleate during the late stage of the transition, and the stacking faults grow as the Cu layer thickens.

A Molecular Dynamics Analysis of Surface Interference and Tip Shape and Size Effects on Atomic-Scale Friction

2005 ◽  
Vol 127 (3) ◽  
pp. 513-521 ◽  
Author(s):  
J. Yang ◽  
K. Komvopoulos
Keyword(s):  
Molecular Dynamics ◽  
Friction Coefficient ◽  
Atomic Scale ◽  
Front Face ◽  
Face Centered Cubic ◽  
Friction Forces ◽  
Face Centered ◽  
Dynamics Simulations ◽  
Insight Into ◽  
Shape And Size

Molecular dynamics simulations of a rigid diamond tip sliding on a face-centered-cubic copperlike substrate were performed in order to examine the dependence of the friction coefficient on the tip–substrate interference and the shape and size of the tip. For a square-base prismatic tip, the friction force is mainly due to interactions of atoms at the front face of the tip and substrate atoms ahead of the tip, while the normal force is due to interactions of atoms at the tip base and substrate atoms under the tip. However, for a pyramidal tip, both normal and friction forces are mainly due to interactions between atoms at the front face of the tip and substrate atoms in the vicinity of the sliding tip. Consequently, the friction coefficient is either sensitive (square-base prismatic tip) or insensitive (pyramidal tip) to the tip–substrate interference distance. In addition, tip size and orientation effects on the friction coefficient were observed with square- and triangle-base prismatic tips, respectively. Lower friction coefficients were obtained with a larger base area and edge-front sliding with a triangle-base prismatic tip. The results provide insight into atomic-scale friction anisotropies due to the effects of the tip size and shape and the tip–substrate interference.

A study of interface sliding at F.C.C.-B.C.C. boundaries in a Cu-Zn alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 422-423
Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin
Keyword(s):  
Face Centered Cubic ◽  
Creep Tests ◽  
High Voltage Electron Microscopy ◽  
Diffusion Treatment ◽  
Voltage Electron ◽  
The Face ◽  
Face Centered ◽  
Interface Sliding ◽  
Zn Alloy ◽  
Made In

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary

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