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

Interaction Between Lattice Dislocations and Grain Boundaries In Ordered Compounds

1990 ◽  
Vol 213 ◽  
Author(s):  
B.J. Pestman ◽  
J. Th. M. De Hosson ◽  
V. Vitek ◽  
F.W. Schapink
Keyword(s):  
Shear Stress ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Partial Dislocation ◽  
Atomistic Simulations ◽  
Many Body ◽  
Shockley Partial Dislocation ◽  
Screw Dislocations ◽  
Applied Shear Stress ◽  
Tilt Boundaries

ABSTRACTThe interaction of 1/2<1 1 0> screw dislocations with symmetric [1 1 0] tilt boundaries was investigated by atomistic simulations using many-body potentials representing ordered compounds. The calculations were performed with and without an applied shear stress. The observations were: absorption into the grain boundary, attraction of a lattice Shockley partial dislocation towards the grain boundary and transmission through the grain boundary under the influence of a shear stress. It was found that the interaction in ordered compounds shows similarities to the interaction in fcc.

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.

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.

Atomistic simulation of shear-coupled motion of [1 1 0] symmetric tilt grain boundary in α-iron

2018 ◽  
Vol 148 ◽  
pp. 141-148 ◽  
Author(s):  
Jian Yin ◽  
Yi Wang ◽  
Xiaohan Yan ◽  
Huaiyu Hou ◽  
Jing Tao Wang
Keyword(s):  
Grain Boundary ◽  
Atomistic Simulation ◽  
Coupled Motion ◽  
Symmetric Tilt ◽  
Tilt Grain Boundary

A Unified Theory of Grain Boundaries I. Symmetric Tilt Boundaries

1973 ◽  
pp. 423-435
Author(s):  
M. J. Marcinkowski ◽  
K. Sadananda ◽  
Wen Feng Tseng
Keyword(s):  
Grain Boundaries ◽  
Unified Theory ◽  
Symmetric Tilt ◽  
Tilt Boundaries

scholarly journals Segregation of P and S Impurities to A Σ9 Grain Boundary in Cu

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1362
Author(s):  
Cláudio M. Lousada ◽  
Pavel A. Korzhavyi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Coordination Number ◽  
High Performance ◽  
Chemical Properties ◽  
Atomic Scale ◽  
Atomic Site ◽  
Segregation Energy ◽  
Physical Chemical ◽  
Symmetric Tilt

The segregation of P and S to grain boundaries (GBs) in fcc Cu has implications in diverse physical-chemical properties of the material and this can be of particular high relevance when the material is employed in high performance applications. Here, we studied the segregation of P and S to the symmetric tilt Σ9 (22¯1¯) [110], 38.9° GB of fcc Cu. This GB is characterized by a variety of segregation sites within and near the GB plane, with considerable differences in both atomic site volume and coordination number and geometry. We found that the segregation energies of P and S vary considerably both with distance from the GB plane and sites within the GB plane. The segregation energy is significantly large at the GB plane but drops to almost zero at a distance of only ≈3.5 Å from this. Additionally, for each impurity there are considerable variations in energy (up to 0.6 eV) between segregation sites in the GB plane. These variations have origins both in differences in coordination number and atomic site volume with the effect of coordination number dominating. For sites with the same coordination number, up to a certain atomic site volume, a larger atomic site volume leads to a stronger segregation. After that limit in volume has been reached, a larger volume leads to weaker segregation. The fact that the segregation energy varies with such magnitude within the Σ9 GB plane may have implications in the accumulation of these impurities at these GBs in the material. Because of this, atomic-scale variations of concentration of P and S are expected to occur at the Σ9 GB center and in other GBs with similar features.

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