scholarly journals A Grain Boundary Regulates the Friction Behaviors between Graphene and a Gold Substrate

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 418 ◽  
Author(s):  
Pinxuan He ◽  
Qiang Cao ◽  
Pengjie Wang ◽  
Huaipeng Wang ◽  
Shaolong Zheng ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Flexible Electronics ◽  
Small Deformation ◽  
Gold Substrate ◽  
Crystal Surfaces ◽  
Friction Forces ◽  
Single Crystal Surfaces ◽  
Lateral Forces ◽  
Dynamics Simulations

The nanofriction of graphene is critical for its broad applications as a lubricant and in flexible electronics. Herein, using a Au substrate as an example, we have investigated the effect of the grain boundary on the nanofriction of graphene by means of molecular dynamics simulations. We have systematically examined the coupling effects of the grain boundary with different mechanical pressures, velocities, temperatures, contact areas, and relative rotation angles on nanofriction. It is revealed that grain boundaries could reduce the friction between graphene and the gold substrate with a small deformation of the latter. Large lateral forces were observed under severe deformation around the grain boundary. The fluctuation of lateral forces was bigger on surfaces with grain boundaries than that on single-crystal surfaces. Friction forces induced by the armchair grain boundaries was smaller than those by the zigzag grain boundaries.

The fracture behaviors of monolayer phosphorene with grain boundaries under tension: a molecular dynamics study

2016 ◽  
Vol 18 (30) ◽  
pp. 20562-20570 ◽  
Author(s):  
Yangyang Guo ◽  
Chong Qiao ◽  
Aihua Wang ◽  
Jinping Zhang ◽  
Songyou Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
Fracture Behaviors ◽  
Dynamics Simulations

The fracture behaviors of monolayer phosphorene with and without a grain boundary have been explored by molecular dynamics simulations.

Vertex Dynamics Simulations of Orientation Dependent Recovery in Deformed Aluminium Single Crystals

2011 ◽  
Vol 702-703 ◽  
pp. 639-642
Author(s):  
Adhish Majumdar ◽  
Claire Maurice ◽  
Julian H. Driver
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Dynamics Simulation ◽  
Boundary Misorientation ◽  
Annealing Behaviour ◽  
The Common ◽  
Dynamics Simulations ◽  
Orientation Dependency ◽  
Good Agreement

A 2-dimensional vertex dynamics simulation is applied to the annealing behaviour of deformed Aluminium single crystals having different orientations. It is observed in experiments that deformed single crystals of different orientations - typically the common rolling textures like Goss (110)[001], Brass (110)[1-12], Cube (001)[100] – exhibit remarkably different rates of recovery. It is suggested that this difference arises from the deformation microstructures, with sub-grain boundaries of various misorientation values. The sub-grain boundary mobilities and energies, being strong functions of the boundary misorientation, thus affect the recovery rates. This effect is illustrated using vertex dynamics simulation on the same orientations and schematic deformation substructures as above. Good agreement is obtained for the orientation dependency of recovery.

Grain Boundary Roughening Transition

2004 ◽  
Vol 467-470 ◽  
pp. 825-834 ◽  
Author(s):  
Duk Yong Yoon ◽  
Young Kyu Cho ◽  
Hyun Min Jang
Keyword(s):  
Molecular Dynamics ◽  
Theoretical Analysis ◽  
Grain Boundary ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
High Temperatures ◽  
Flat Surfaces ◽  
Roughening Transition ◽  
Entropy Effect ◽  
Dynamics Simulations

Flat surfaces and grain boundaries lying on low crystal planes are singular corresponding to the cusps in the polar (Wulff) plots of their energy against their orientation. The theoretical analysis of the entropy effect at high temperatures shows that these interfaces undergo roughening transitions. The molecular dynamics simulations also show disordering to liquid-like structures at high temperatures that can be interpreted as the roughening transition. Experimentally, singular flat surfaces and grain boundaries become curved at high temperatures or with additives, indicating their roughening transition. The grain boundaries in polycrystals are often faceted with hill-and-valley shapes and their defaceting at high temperatures also show their roughening transition.

scholarly journals Molecular dynamics simulations of nanoindentation and scratch in Cu grain boundaries

2017 ◽  
Vol 8 ◽  
pp. 2283-2295 ◽  
Author(s):  
Shih-Wei Liang ◽  
Ren-Zheng Qiu ◽  
Te-Hua Fang
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
Md Simulations ◽  
Barrier Effect ◽  
Cu Films ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Main Factor

The dynamic nanomechanical characteristics of Cu films with different grain boundaries under nanoindentation and scratch conditions were studied by molecular dynamics (MD) simulations. The type of grain boundary is the main factor in the control of the substrate atoms with respect to the size of dislocations since the existence of the grain boundary itself restricts the movement associated with dislocations. In this work, we analyzed the transverse and vertical grain boundaries for different angles. From the simulation results, it was found that the sample with a transverse grain boundary angle of 20° had a higher barrier effect on the slip band as compared to samples with other angles. Moreover, the nanoindentation results (i.e., indentation on the upper area) of the vertical grain boundary showed that the force was translated along the grain boundary, thereby producing intergranular fractures.

Molecular Dynamics Studies of Spalling and Melting in Shocked Nanocrystalline Pb

2013 ◽  
Vol 577-578 ◽  
pp. 613-616
Author(s):  
Mei Zhen Xiang ◽  
Hai Bo Hu ◽  
Jun Chen
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Tensile Stress ◽  
Grain Boundaries ◽  
Shock Intensity ◽  
Void Growth ◽  
Shock Loading ◽  
Spall Strength ◽  
Boundary Effects ◽  
Dynamics Simulations

The mechanisms of spalling and melting in nanocrystalline Pb under shock loading are studied by molecular dynamics simulations. Our results show that grain boundaries have significant influences on spalling behaviors in cases of classical spallation and releasing melting. In these cases, cavitation and melting both start on grain boundaries, and they display mutual promotion: melting makes the voids nucleate at smaller tensile stress, and void growth speeds melting. Due to grain boundary effects, the spall strength of nanocrystalline Pb varies slowly with the shock intensity in cases of classical spallation. In cases of releasing melting and compression melting, spall strength of both single-crystalline and nanocrystalline Pb drops dramatically as shock intensity increases.

Introducing Solute Drag in Irregular Cellular Automata Modeling of Grain Growth

2004 ◽  
Vol 467-470 ◽  
pp. 1045-1050 ◽  
Author(s):  
Koenraad G.F. Janssens ◽  
Elizabeth A. Holm ◽  
Stephen M. Foiles
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Boundary Energy ◽  
Solute Drag ◽  
Solute Concentration ◽  
Local Concentration ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Dynamics Simulations

In this paper we discuss the principles of a combined approach to solve the problem of solute drag as it occurs in microstructure evolution processes such as grain growth, recrystallization and phase transformation. A recently developed irregular grid cellular automaton is used to simulate normal grain growth, in which the energy of the grain boundaries is the driving force. A new, discrete diffusion model is used to simulate solute segregation to the grain boundaries. The local concentration of the solute is then taken into account in the calculation of the local grain boundary mobility and/or grain boundary energy, thereby constituting a drag force. The relation between solute concentration and grain boundary mobility/energy is derived from molecular dynamics simulations.

Effect of Grain Boundaries on Fracture Toughness in Ultrafine-Grained Metals by Atomic-Scale Computational Experiments

2012 ◽  
Vol 706-709 ◽  
pp. 1841-1846
Author(s):  
Tomotsugu Shimokawa ◽  
Masaki Tanaka ◽  
Kenji Higashida
Keyword(s):  
Fracture Toughness ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Atomic Scale ◽  
Boundary Structure ◽  
Shielding Effect ◽  
Mechanical Field ◽  
Ultrafine Grained ◽  
Crack Tips ◽  
Dynamics Simulations

In order to investigate roles of grain boundaries on the improved fracture tough-ness in ultrafine-grained metals, interactions between crack tips, dislocations, and disclinationdipoles at grain boundaries are performed to aluminium bicrystal models containing a crackand h112i tilt grain boundaries using molecular dynamics simulations. A proposed mechanismto express the improved fracture toughness in ultrafine-grained metals is the disclination shield-ing effect on the crack tip mechanical field. The disclination shielding can be activated whena transition of dislocation sources from crack tips to grain boundaries and a transition of thegrain boundary structure into a neighbouring energetically stable boundary by emitting dis-locations from the grain boundary occur. The disclination shielding effect becomes large asdislocations are continuously emitted from the grain boundary without dislocation emissionsfrom crack tips. This mechanism can further shield the mechanical field around the crack tipand obtain the plastic deformation by dislocation emissions from grain boundaries, hence itcan be expected that the disclination shielding effect can improve the fracture toughness inultrafine-grained metals

Atomistic Simulation of Grain Boundaries of the Twin Limited Structure in Ni3Al

1994 ◽  
Vol 364 ◽  
Author(s):  
Maria-Lynn Turi ◽  
R. Zugic ◽  
B. Szpunar ◽  
U. Erb ◽  
G. Palumbo ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Atomistic Simulation ◽  
Boundary Energy ◽  
Boundary Plane ◽  
Embedded Atom Method ◽  
Grain Boundary Energy ◽  
Embedded Atom ◽  
Grain Boundary Plane ◽  
Dynamics Simulations

AbstractEmbedded atom method molecular dynamics simulations of low Σ grain boundaries in Ni3Al are presented. The results show that the grain boundary plane has a larger effect on grain boundary energy than the Σ value, rigid body translations and stoichiometry. Assessment of the energies of Σ3n (n ≥ 1) grain boundaries in Ni3Al for various grain boundary planes indicates that only the Σ3 grain boundary is energetically preferred. The implications of this result for the development of the twin limited structure based on energetic considerations are discussed.

Measurement of the Displacement Across a Coincidence Grain Boundary

1977 ◽  
Vol 35 ◽  
pp. 124-125
Author(s):  
J. W. Matthews ◽  
W. M. Stobbs
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Stacking Fault ◽  
The Other ◽  
Measuring Technique ◽  
High Angle ◽  
Twin Boundaries ◽  
Rigid Displacement ◽  
Cubic Crystals ◽  
Lattice Displacement

Many high-angle grain boundaries in cubic crystals are thought to be either coincidence boundaries (1) or coincidence boundaries to which grain boundary dislocations have been added (1,2). Calculations of the arrangement of atoms inside coincidence boundaries suggest that the coincidence lattice will usually not be continuous across a coincidence boundary (3). There will usually be a rigid displacement of the lattice on one side of the boundary relative to that on the other. This displacement gives rise to a stacking fault in the coincidence lattice.Recently, Pond (4) and Smith (5) have measured the lattice displacement at coincidence boundaries in aluminum. We have developed (6) an alternative to the measuring technique used by them, and have used it to find two of the three components of the displacement at {112} lateral twin boundaries in gold. This paper describes our method and presents a brief account of the results we have obtained.

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

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