scholarly journals Formation of fivefold deformation twins in nanocrystalline face-centered-cubic copper based on molecular dynamics simulations

2006 ◽  
Vol 89 (4) ◽  
pp. 041919 ◽  
Author(s):  
A. J. Cao ◽  
Y. G. Wei
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Face Centered Cubic ◽  
Deformation Twins ◽  
Face Centered ◽  
Dynamics Simulations

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.

Molecular Dynamics Simulations of Nanocrystalline Nickel and Copper Revealing Different Failure Model of FCC Metals

2009 ◽  
Vol 633-634 ◽  
pp. 31-38
Author(s):  
Ajing Cao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
Large Scale ◽  
Uniaxial Tensile ◽  
Face Centered Cubic ◽  
Triple Junctions ◽  
Fcc Metals ◽  
Face Centered ◽  
Dynamics Simulations

We have previously reported that the fracture behavior of nanocrystalline (NC) Ni is via the nucleation and coalescence of nano-voids at grain boundaries and triple junctions, resulting in intergranular failure mode. Here we show in large-scale molecular dynamics simulations that partial-dislocation-mediated plasticity is dominant in NC Cu with grain size as small as ~ 10 nanometers. The simulated results show that NC Cu can accommodate large plastic strains without cracking or creating damage in the grain interior or grain boundaries, revealing their intrinsic ductile properties compared with NC Ni. These results point out different failure mechanisms of the two face-centered-cubic (FCC) metals subject to uniaxial tensile loading. The insight gained in the computational experiments could explain the good plasticity found in NC Cu not seen in Ni so far.

Molecular Dynamics Simulation of the Variation in the Microstructure of a Polycrystalline Material under Tensile Load

2017 ◽  
Vol 748 ◽  
pp. 375-380 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Molecular Dynamics ◽  
External Load ◽  
Crystal Orientation ◽  
Tensile Load ◽  
Edge Length ◽  
Dynamics Simulation ◽  
Polycrystalline Materials ◽  
Face Centered Cubic ◽  
Face Centered ◽  
Dynamics Simulations

Molecular dynamics simulations were carried out to investigate the change in the crystal orientation of polycrystalline materials placed under an external load. Two models were prepared, both comprising four grains but with different grain arrangements. Each grain had a face-centered cubic structure with (001) face on the x-y plane, whereas each grain had a different rotation of orientation around the z-axis. A tensile load was applied by extending the edge length in the y direction while the other directions were kept stress-free. As a result, a significant change in the microstructure was observed, with changes in both crystal orientation and shape along with the formation of subgrains. The structure and direction of the grain boundary against the external load were also found to affect the change in the microstructure.

Molecular dynamics simulation of screw dislocation interaction with stacking fault tetrahedron in face-centered cubic Cu

2007 ◽  
Vol 22 (10) ◽  
pp. 2758-2769 ◽  
Author(s):  
Hyon-Jee Lee ◽  
Jae-Hyeok Shim ◽  
Brian D. Wirth
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Stacking Fault ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Dislocation Interaction ◽  
Complete Absorption ◽  
Stacking Fault Tetrahedron ◽  
Face Centered ◽  
Dynamics Simulations

The interaction of a gliding screw dislocation with stacking fault tetrahedron (SFT) in face-centered cubic (fcc) copper (Cu) was studied using molecular dynamics simulations. Upon intersection, the screw dislocation spontaneously cross slips on the SFT face. One of the cross-slipped Shockley partials glides toward the SFT base, partially absorbing the SFT. At low applied stress, partial absorption produces a superjog, with detachment of the trailing Shockley partial via an Orowan process. This leaves a small perfect SFT and a truncated base behind, which subsequently form a sheared SFT with a pair of opposite sense ledges. At higher applied shear stress, the ledges can self-heal by gliding toward an SFT apex and transform the sheared SFT into a perfect SFT. However, complete absorption or collapse of an SFT (or sheared SFT) by a moving screw dislocation is not observed. These observations provide insights into defect-free channel formation in deformed irradiated Cu.

Molecular dynamics studies on the grain growth of nanocrystalline Ni and Ni3Al

2017 ◽  
Vol 31 (26) ◽  
pp. 1750237
Author(s):  
Zi-Yue Zhang
Keyword(s):  
Molecular Dynamics ◽  
Boundary Migration ◽  
Detailed Comparison ◽  
Face Centered Cubic ◽  
Grain Rotation ◽  
Face Centered ◽  
Dynamics Simulations ◽  
Curvature Driven ◽  
Grain Coalescence ◽  
Very High

With molecular dynamics simulations, the growth of face-centered-cubic nanocrystalline materials Ni and Ni3Al has been studied. It is found that grain-rotation induced grain coalescence and curvature-driven grain-boundary migration are dominant mechanisms in the nanograin growth. A detailed comparison of the nanograin growth between the two systems is discussed in terms of grain rotation and grain sliding. We also study the temperature effect and the size effect in the nanograin growth. The tendency of twinning in the nanograin growth is discussed. It is found that in Ni3Al, it seems more possible for nanograins to grow into twin-like structures than single crystal unless at very high temperatures.

scholarly journals Cubic-to-Tetragonal Phase Transitions in Ag–Cu Nanorods

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Francesco Delogu ◽  
Michele Mascia
Keyword(s):  
Molecular Dynamics ◽  
Phase Transitions ◽  
Cross Section ◽  
Elastic Energy ◽  
Structural Behavior ◽  
Face Centered Cubic ◽  
Cubic Structure ◽  
Face Centered ◽  
Dynamics Simulations ◽  
Coherent Interfaces

Molecular dynamics simulations have been used to investigate the structural behavior of nanorods with square cross section. The nanorods consist of pure Ag and Cu phases or of three Ag and Cu domains in the sequence Ag–Cu–Ag or Cu–Ag–Cu. Ag and Cu domains are separated by coherent interfaces. Depending on the side length and the size of individual domains, Ag and Cu can undergo a transition from the usual face-centered cubic structure to a body-centered tetragonal one. Such transition can involve the whole nanorod, or only the Ag domains. In the latter case, the transition is accompanied by a loss of coherency at the Ag–Cu interfaces, with a consequent release of elastic energy. The observed behaviors are connected with the stresses developed at the nanorod surfaces.

scholarly journals Ab Initio Phase Diagram of Copper

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 537
Author(s):  
Samuel R. Baty ◽  
Leonid Burakovsky ◽  
Daniel Errandonea
Keyword(s):  
Molecular Dynamics ◽  
Phase Diagram ◽  
Ab Initio ◽  
Solid Phase ◽  
Quantum Molecular Dynamics ◽  
Face Centered Cubic ◽  
Melting Curves ◽  
Solid Phases ◽  
Face Centered ◽  
Dynamics Simulations

Copper has been considered as a common pressure calibrant and equation of state (EOS) and shock wave (SW) standard, because of the abundance of its highly accurate EOS and SW data, and the assumption that Cu is a simple one-phase material that does not exhibit high pressure (P) or high temperature (T) polymorphism. However, in 2014, Bolesta and Fomin detected another solid phase in molecular dynamics simulations of the shock compression of Cu, and in 2017 published the phase diagram of Cu having two solid phases, the ambient face-centered cubic (fcc) and the high-PT body-centered cubic (bcc) ones. Very recently, bcc-Cu has been detected in SW experiments, and a more sophisticated phase diagram of Cu with the two solid phases was published by Smirnov. In this work, using a suite of ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology, which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase boundaries, we refine the phase diagram of Smirnov. We calculate the melting curves of both fcc-Cu and bcc-Cu and obtain an equation for the fcc-bcc solid–solid phase transition boundary. We also obtain the thermal EOS of Cu, which is in agreement with experimental data and QMD simulations. We argue that, despite being a polymorphic rather than a simple one-phase material, copper remains a reliable pressure calibrant and EOS and SW standard.

Structure, Stability and Properties of Covalent C34, C20, and C22 Crystals

1994 ◽  
Vol 359 ◽  
Author(s):  
G. Benedek ◽  
L. Colombo ◽  
B. Corona ◽  
E. Galvani ◽  
S. Sanguinetti ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Electronic Properties ◽  
Infinite Number ◽  
Cohesive Energy ◽  
Structure Stability ◽  
Face Centered Cubic ◽  
Cubic Lattice ◽  
Bonding Structure ◽  
Face Centered ◽  
Dynamics Simulations

ABSTRACTTopological arguments indicate that an infinite number of covalent carbon crystals may exist with either diamond-like (sp3), graphitic-like (sp2)- or mixed (sp3/sp2) bonding structure. We investigate the structural, elastic and electronic properties of three prototypical structure: C34, C20 and C22, respectively. All of them form a face-centered cubic lattice. Their properties have been calculated by both Montecarlo and molecular dynamics simulations based on the Tersoff potential. Both the sp3-bonded C34 and the sp2-bonded C20 are found to have a cohesive energy per atom very close to that of diamond. A comparison of elastic and electronic properties to those ones of diamond and graphite are also presented and discussed.

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