Atomistic simulations of effect of hydrogen atoms on mechanical behaviour of an α -Fe with symmetric tilt grain boundaries

2018 ◽  
Vol 382 (35) ◽  
pp. 2464-2469 ◽  
Author(s):  
H.Y. Song ◽  
C.F. Li ◽  
S.F. Geng ◽  
M.R. An ◽  
M.X. Xiao ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Mechanical Behaviour ◽  
Atomistic Simulations ◽  
Hydrogen Atoms ◽  
Symmetric Tilt

Analysis of Oxygen Vacancy Trapping at [001] Symmetric Tilt Grain Boundaries in Barium Titanate by Atomistic Simulations

2010 ◽  
Vol 445 ◽  
pp. 39-42 ◽  
Author(s):  
Takashi Oyama ◽  
Nobuyuki Wada ◽  
Hiroshi Takagi
Keyword(s):  
Barium Titanate ◽  
Grain Boundaries ◽  
Atomistic Simulation ◽  
Oxygen Vacancies ◽  
Atomistic Simulations ◽  
Multilayer Ceramic Capacitors ◽  
Simulation Techniques ◽  
Electrical Degradation ◽  
Symmetric Tilt

The role of grain boundaries (GBs) in the diffusion of oxygen vacancies (VO••s) in barium titanate (BaTiO3) and its mechanism were investigated using atomistic simulation techniques. It was found that GBs trapped VO••s at specific sites in the course of the diffusion, and the excess energy reflecting structural distortion of the GB was closely related to the availability of the trapping. GBs therefore act as a resistance of the diffusion of VO••s, suggesting that electrical degradation of multilayer ceramic capacitors (MLCCs), which is derived from vacancy diffusion, enables to be additionally improved by controlling GB structures in BaTiO3-based dielectrics.

Atomistic Simulations of [001] Symmetric Tilt Boundaries in Ni3Al

1986 ◽  
Vol 81 ◽  
Author(s):  
S. P. Chen ◽  
A. F. Voter ◽  
D. J. Srolovitz
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Simulation Study ◽  
Atomistic Simulation ◽  
Atomistic Simulations ◽  
Boundary Composition ◽  
Symmetric Tilt ◽  
Tilt Boundaries ◽  
Cohesive Energies

AbstractWe report a systematic atomistic simulation study of [001] symmetric tilt grain boundaries (GB) in Ni3Al, Ni, and Al. We found that the grain boundary energies and cohesive energies of Ni3Al and pure fcc Ni are approximately thesame. Grain boundary energies aid cohesive energies in Ni3Al depends stronglyon the grain boundary composition. The Al-rich boundaries have highest grain boundary energies and lowest cohesive energies. This offers an explanation for the stoichiometric effect on the boron ductilization

Atomistic Simulation on Hydrogen Storage in Metallic Nanoparticles

2009 ◽  
Vol 1216 ◽  
Author(s):  
Hiroshi Ogawa ◽  
Megumi Kayanuma ◽  
Masahiko Katagiri
Keyword(s):  
Hydrogen Storage ◽  
Grain Boundaries ◽  
Metallic Nanoparticles ◽  
Particle Surface ◽  
Hydrogen Distribution ◽  
Hydrogen Atoms ◽  
Crystal Lattices ◽  
Symmetric Tilt ◽  
Hydrogen Interaction ◽  
Potential Parameters

AbstractHydrogen storage in metallic nanoparticles was investigated by classical molecular dynamics and parameter physics. We observed phenomenological variation due to the differences in potential parameters of metal-hydrogen pair and crystal lattices. Three patterns of hydrogen distribution in both b.c.c. and f.c.c. nanoparticles were observed: non-absorbing, homogeneously-absorbing and heterogeneously-absorbing. In the last case, hydrogen atoms distribute just beneath the particle surface to form a hydrogen-rich layer. This layer prevents the diffusive motions of hydrogen atoms into the nanoparticle. We also carried out long simulation runs up to 1 nm to observed the structural variation of nanoparticles due to hydrogenation. Generation of grain boundaries was observed in b.c.c nanoparticles with the condition of strong metal–hydrogen interaction. Most of the grain boundaries were symmetric-tilt type and migrated inside the particle to reduce the interface energies. Formation of grain boundary was not observed in f.c.c. nanoparticles.

scholarly journals Modelling Hydrogen Embrittlement using Density Functional Theory: A theoretical approach to understanding environmentally assisted cracking in 7xxx series aluminium alloys

2020 ◽  
Vol 326 ◽  
pp. 04006
Author(s):  
Benjamin T. Wilson ◽  
Joseph D. Robson ◽  
Christopher P. Race
Keyword(s):  
Density Functional Theory ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cohesive Zone ◽  
Density Functional ◽  
Atomistic Simulations ◽  
Functional Theory ◽  
Minimal Impact ◽  
Symmetric Tilt ◽  
Environmentally Assisted Cracking

The effects of H segregation to a Σ11 symmetric tilt Al grain boundary are investigated using atomistic simulations, as part of a wider study on cracking in 7xxx series alloys. Density functional theory based simulations of uniaxial straining of grain boundaries containing 11 different concentrations of H were performed under the cohesive zone fracture mechanics framework. The theoretical strength of grain boundaries is shown to be supressed by H segregation, and the cause of this is attributed to the prevention of the formation of Al ligaments across grain boundaries. Segregated concentrations of relevant alloying elements (Zn, Mg, and Cu) show minimal impact on the H embrittlement process investigated, namely H enhanced decohesion (HEDE). Further modelling, of H transport and grain boundary precipitates, is required to confirm the validity of the HEDE mechanism in the case of 7xxx alloys.

THE STRENGTH OF SUBMICRON-SIZED MATERIALS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3579-3586 ◽  
Author(s):  
A. H. W. NGAN ◽  
P. C. WO ◽  
L. ZUO ◽  
H. LI ◽  
N. AFRIN
Keyword(s):  
Yield Strength ◽  
Time Dependence ◽  
Experimental Evidence ◽  
Mechanical Behaviour ◽  
Survival Probability ◽  
Diffusion Length ◽  
Theoretical Explanation ◽  
Atomistic Simulations ◽  
Load Range ◽  
Scaling Model

Recent rapid advancements in nano- and micro-machinery technologies call for an urgent need to understand the mechanical behaviour of materials of dimensions in the sub-micron regime. The initial yield strength of submicron crystals exhibits remarkable statistical scatter as well as dependence upon size and time under load. Submicron-sized materials are also found to creep many orders of magnitude faster than bulk counterparts. In this paper, the recent experimental evidence for these phenomena is reviewed. Theoretical explanation of these phenomena is also discussed. The statistical scatter and time dependence of the yield strength are interpreted by a scaling model derived from atomistic simulations. The results indicate that, within a certain load range, the strength of a sub-micron sized material is not deterministic and can only be described by a survival probability. The much faster creep in the submicron regime is interpreted in terms of the much shorter diffusion length compared to bulk creep.

A theoretical study of wrinkle propagation in graphene with flower-like grain boundaries

2021 ◽  
Author(s):  
Zihui Zhao ◽  
Yafei Wang ◽  
Changguo Wang
Keyword(s):  
Grain Boundaries ◽  
Theoretical Study ◽  
Atomistic Simulations ◽  
Dynamic Surface ◽  
Surface Wrinkle

This study investigated dynamic surface wrinkle propagation across a series of flower-like rotational grain boundaries (GBs) in graphene using theoretical solutions and atomistic simulations. It was found that there was...

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