Influence of Crystallographic Orientation on the Mechanical Properties and Deformation Behavior of Ni Nanowire Using Large Scale Molecular Dynamics

2021 ◽  
pp. 75-84
Author(s):  
Krishna Chaitanya Katakam ◽  
Sudhakar Rao Gorja ◽  
Natraj Yedla
Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5351
Author(s):  
Ahmed Tamer AlMotasem ◽  
Matthias Posselt ◽  
Tomas Polcar

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.


RSC Advances ◽  
2016 ◽  
Vol 6 (16) ◽  
pp. 13548-13553 ◽  
Author(s):  
Sara Adibi ◽  
Paulo S. Branicio ◽  
Roberto Ballarini

Large-scale molecular-dynamics simulations are used to investigate the mechanical properties of 50 nm diameter Cu64Zr36 nanolaminate nanopillars constructed from 5 nm thick layers of metallic glass (MG) or MG and 5 nm grain sized nanoglass.


Author(s):  
H. F. ZHAN ◽  
K. XIA ◽  
Y. T. GU

Graphene has been reported with record-breaking properties which have opened up huge potential applications. A considerable research has been devoted to manipulate or modify the properties of graphene to target a more smart nanoscale device. Graphene and carbon nanotube hybrid structure (GNHS) is one of the promising graphene derivative, whose mechanical properties have been rarely discussed in literature. Therefore, the mechanical properties of GNHS is studied in this paper based on the large-scale molecular dynamics simulation. The target GNHS is constructed by considering two separate graphene layers that are being connected by single-wall carbon nanotubes (SWCNTs) according to the experimental observations. It is found that the GNHSs exhibit much lower yield strength, Young's modulus, and earlier yielding compared to bilayer graphene sheet. Fracture of GNHSs is found to initiate at the connecting region between carbon nanotubes (CNTs) and graphene. After failure, monatomic chains are normally observed at the front of the failure region, and the two graphene layers at the failure region without connecting CNTs will adhere to each other, generating a bilayer graphene sheet scheme (with a layer distance about 3.4 Å). This study will enrich the current understanding of the mechanical performance of GNHS, which will guide the design of GNHS and shed light on its various applications.


2020 ◽  
pp. 2150141
Author(s):  
Meixia Xiao ◽  
Haiyang Song ◽  
Minrong An

The effects of grain boundary (GB) and defect on the deformation behaviors of graphene under tension or compression in directions perpendicular ([Formula: see text]-axis) or parallel ([Formula: see text]-axis) to GB are investigated by molecular dynamics (MD) simulation. The results show that the bicrystalline graphene can sustain more load under tension along [Formula: see text]-axis than along [Formula: see text]-axis, and that regardless of tensile directions, the yield strength of bicrystalline graphene with high misorientation angle is higher than that with low angle. Furthermore, we found that the effect of GB on the deformation behavior of graphene under compression strain along [Formula: see text]-axis is more obvious than that along [Formula: see text]-axis.


Author(s):  
Hanae Chabba ◽  
Driss Dafir

Aluminum alloys development always exit in the manufacturing process. Al/Mg alloys have been attracted significant attention because of their excellent mechanical properties. The microstructural evolution and deformation mechanisms are still challenging issues, and it is hard to observe directly by experimental methods. Accordingly, in this paper atomic simulations are performed to investigate the uniaxial compressive behavior of Al/Mg phases; with different ratio of Mg ranging from 31% to 56%. The compression is at the same strain rate (3.1010 s⁻¹), at the same temperature (300K) and pressure, using embedded atom method (EAM) potential to model the interactions and the deformation behavior between Al and Mg.From these simulations, we get the radial distribution function; the stress–strain responses to describe the elastic and plastic behaviors of β-Al3Mg2, ε-Al30Mg23, Al1Mg1 and γ-Al12Mg17 phases with 31, 41, 50 and 56% of Mg added to pure aluminum, respectively. The mechanical properties, such as Young’s modulus, elasticity limit and rupture pressure, are determined and presented. The engineering equation was used to plot the stress-strain curve for each phase.From the results obtained, the chemical composition has a significant effect on the properties of these phases. The stress-strain behavior comprised elastic, yield, strain softening and strain hardening regions that were qualitatively in agreement with previous simulations and experimental results. These stress-strain diagrams obtained show a rapid increase in stress up to a maximum followed by a gradual drop when the specimen fails by ductile fracture. Under compression, the deformation behavior of β-Al3Mg2 and γ-Al12Mg17 phases is slightly similar. From the results, it was found that ε-Al30Mg23 phase are brittle under uniaxial compressive loading and γ-Al12Mg17 phase is very ductile under the same compressive loading.The engineering stress-strain relationship suggests that β-Al3Mg2 and γ-Al12Mg17 phases have high elasticity limit, ability to resist deformation and also have the advantage of being highly malleable. From this simulation, we also find that the mechanical properties under compressive load of ε-Al30Mg23 phase are evidently less than other phases, which makes it the weakest phase. The obtained results were compared with the previous experimental studies, and generally, there is a good correlation.The Al-Mg system was built and simulated using molecular dynamics (MD) software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator).


2019 ◽  
Author(s):  
Liqun Cao ◽  
Jinzhe Zeng ◽  
Mingyuan Xu ◽  
Chih-Hao Chin ◽  
Tong Zhu ◽  
...  

Combustion is a kind of important reaction that affects people's daily lives and the development of aerospace. Exploring the reaction mechanism contributes to the understanding of combustion and the more efficient use of fuels. Ab initio quantum mechanical (QM) calculation is precise but limited by its computational time for large-scale systems. In order to carry out reactive molecular dynamics (MD) simulation for combustion accurately and quickly, we develop the MFCC-combustion method in this study, which calculates the interaction between atoms using QM method at the level of MN15/6-31G(d). Each molecule in systems is treated as a fragment, and when the distance between any two atoms in different molecules is greater than 3.5 Å, a new fragment involved two molecules is produced in order to consider the two-body interaction. The deviations of MFCC-combustion from full system calculations are within a few kcal/mol, and the result clearly shows that the calculated energies of the different systems using MFCC-combustion are close to converging after the distance thresholds are larger than 3.5 Å for the two-body QM interactions. The methane combustion was studied with the MFCC-combustion method to explore the combustion mechanism of the methane-oxygen system.


2020 ◽  
Author(s):  
Jin Soo Lim ◽  
Jonathan Vandermause ◽  
Matthijs A. van Spronsen ◽  
Albert Musaelian ◽  
Christopher R. O’Connor ◽  
...  

Restructuring of interface plays a crucial role in materials science and heterogeneous catalysis. Bimetallic systems, in particular, often adopt very different composition and morphology at surfaces compared to the bulk. For the first time, we reveal a detailed atomistic picture of the long-timescale restructuring of Pd deposited on Ag, using microscopy, spectroscopy, and novel simulation methods. Encapsulation of Pd by Ag always precedes layer-by-layer dissolution of Pd, resulting in significant Ag migration out of the surface and extensive vacancy pits. These metastable structures are of vital catalytic importance, as Ag-encapsulated Pd remains much more accessible to reactants than bulk-dissolved Pd. The underlying mechanisms are uncovered by performing fast and large-scale machine-learning molecular dynamics, followed by our newly developed method for complete characterization of atomic surface restructuring events. Our approach is broadly applicable to other multimetallic systems of interest and enables the previously impractical mechanistic investigation of restructuring dynamics.


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