Intergranular Total Energy Maps and the Structure of a Grain Boundary

We present the results of atomistic simulations of the decohesion process of the Σ3(111) GB with boron additives. On the basis of the generalized simulated annealing formalism we demonstrate that accounting for angle-dependent three-body interactions leads to the formation of a minimum in the energy profile in the decohesion process and to the enhancement of the boron-induced interatomic interaction across the GB. Our study of the detailed atomic configuration of the GB predicts the effect of the "grain boundary separation" that is induced by the interstitial impurity. The interatomic potentials used in these simulations were obtained from ab initio total energy calculations on the basis of a recursion procedure.

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Ab Initio Investigation of Grain Boundary Sliding

MRS Proceedings ◽

10.1557/proc-408-283 ◽

1995 ◽

Vol 408 ◽

Author(s):

M. C. Payne ◽

G. P. Francis ◽

C. Molteni ◽

N. Marzari ◽

V. Deyirmenjian ◽

...

Keyword(s):

Grain Boundary ◽

Total Energy ◽

Ab Initio ◽

Grain Boundary Sliding ◽

Microscopic Level ◽

Extensive Investigation ◽

Preliminary Results ◽

Pseudopotential Calculations ◽

Covalently Bonded ◽

Boundary Sliding

AbstractWe are using total energy pseudopotential calculations to carry out an extensive investigation into grain boundary sliding in a number of different systems, in order to understand, at microscopic level, the fundamental mechanisms responsible for this process.In this paper we present results for the sliding process at the ∑ = 5(001) twist grain boundary in germanium, chosen as a typical covalently bonded material, and contrast them with preliminary results obtained for the ∑ = 5 (001) twist grain boundary in aluminium, a typical metal.

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Temperature and Strain Rate Effects in Grain Boundary Sliding

MRS Proceedings ◽

10.1557/proc-408-277 ◽

1995 ◽

Vol 408 ◽

Cited By ~ 1

Author(s):

C. Molteni ◽

G. P. Francis ◽

M. C. Payne ◽

V. Heine

Keyword(s):

Grain Boundary ◽

Strain Rate ◽

Total Energy ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Grain Boundary Sliding ◽

Total Energy Density ◽

Energy Density Functional ◽

Strain Rate Effects ◽

Rate Effects

AbstractWe have performed total energy density functional theory calculations to investigate the sliding process at the ∑ = 5 (001) twist grain boundary in germanium. The accurate quantum mechanical description of the interatomic bonding provides valuable insights into the mechanisms of bond breaking and remaking that occur during the sliding.In this paper we show how total energy calculations can be used to describe finite temperature and strain rate effects in this grain boundary.

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NONEMPIRICAL SIMULATIONS OF Σ3 TUNGSTEN GRAIN BOUNDARY WITH BORON ATOMS

Surface Review and Letters ◽

10.1142/s0218625x9900069x ◽

1999 ◽

Vol 06 (05) ◽

pp. 705-718 ◽

Cited By ~ 6

Author(s):

DAVID FUKS ◽

KLEBER MUNDIM ◽

VLAD LIUBICH ◽

SIMON DORFMAN

Keyword(s):

Density Functional Theory ◽

Grain Boundary ◽

Total Energy ◽

Ab Initio ◽

Density Functional ◽

Atomistic Simulations ◽

Interatomic Potentials ◽

Potential Approximation ◽

Functional Theory ◽

Energy Calculations

We perform the atomistic simulations of the properties of the Σ3< 111> grain boundary in W and demonstrate the influence of boron additive on the resistance of the grain boundary with respect to different shifts. The interatomic potentials used in these simulations are obtained from ab initio total energy calculations. These calculations are carried out in the framework of density functional theory in the coherent potential approximation. The recursion procedure to extract A–B type interatomic potentials is suggested.

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Модель растворения пор на границах зерен при отжиге ультрамелкозернистого алюминиевого сплава

Письма в журнал технической физики ◽

10.21883/pjtf.2021.18.51472.18872 ◽

2021 ◽

Vol 47 (18) ◽

pp. 40

Author(s):

М.Ю. Гуткин ◽

Т.С. Орлова ◽

Н.В. Скиба

Keyword(s):

Theoretical Model ◽

Grain Boundary ◽

Total Energy ◽

Grain Boundaries ◽

Ultrafine Grained ◽

Model Pore ◽

Ultrafine Grained Materials ◽

Good Agreement ◽

Zr Alloy

A theoretical model which describes the mechanism of pore dissolution at grain boundaries in ultrafine-grained materials during the ageing annealing is suggested. Within the framework of the model, pore dissolution occurs due to the emission of vacancies and the climb of grain-boundary dislocations along the grain boundary towards the pore. It is shown that in this case there is a significant decrease in the total energy of the system. The results of the model are in good agreement with the available experimental observations of pore dissolution during annealing of ultrafine-grained Al-Zr alloy.

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An Ab Initio Investigation of a Grain Boundary in a Transition Metal Oxide

MRS Proceedings ◽

10.1557/proc-408-271 ◽

1995 ◽

Vol 408 ◽

Cited By ~ 1

Author(s):

I. Dawson ◽

P. D. Bristowe. ◽

M. C. Payne ◽

M-H. Lee

Keyword(s):

Electronic Structure ◽

Transition Metal ◽

Grain Boundary ◽

Metal Oxide ◽

Total Energy ◽

Ab Initio ◽

Transition Metal Oxide ◽

The Stability ◽

Energy Plane ◽

Translation State

AbstractWe have used ab initio total energy plane wave pseudopotential methods to perform the first completely ab initio investigation of the atomic and electronic structure of a grain boundary in a transition metal oxide. The ∑ = 15 (210)[001] tilt boundary in rutile TiG2 is studied using the conjugate gradients iterative minimisation technique for performing total energy calculations within the LDA and pseudopotential approximations. The stability of the experimentally observed translation state of the boundary is confirmed, and some insight is gained into its electronic structure.

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Dependence of Intergranular Fracture on Boundary Topography and Cohesion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071193 ◽

1973 ◽

Vol 31 ◽

pp. 150-151

Author(s):

J. E. Doherty ◽

A. F. Giamei ◽

B. H. Kear ◽

C. W. Steinke

Keyword(s):

Grain Boundary ◽

Room Temperature ◽

Nickel Base Superalloy ◽

Boundary Shear ◽

Room Temperature Ductility ◽

Solid Solution Matrix ◽

Nickel Base ◽

Solution Matrix ◽

Different Levels ◽

Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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Two Investigations into Grain Boundary Structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080833 ◽

1977 ◽

Vol 35 ◽

pp. 688-691

Author(s):

P. Humble

Keyword(s):

Grain Boundary ◽

Dark Field ◽

Boundary Structure ◽

Boundary Dislocation ◽

Bright Field ◽

Intrinsic Structure ◽

Weak Beam ◽

Grain Boundary Structure ◽

Independent Information ◽

Diffraction Patterns

There has been sustained interest over the last few years into both the intrinsic (primary and secondary) structure of grain boundaries and the extrinsic structure e.g. the interaction of matrix dislocations with the boundary. Most of the investigations carried out by electron microscopy have involved only the use of information contained in the transmitted image (bright field, dark field, weak beam etc.). Whilst these imaging modes are appropriate to the cases of relatively coarse intrinsic or extrinsic grain boundary dislocation structures, it is apparent that in principle (and indeed in practice, e.g. (1)-(3)) the diffraction patterns from the boundary can give extra independent information about the fine scale periodic intrinsic structure of the boundary.In this paper I shall describe one investigation into each type of structure using the appropriate method of obtaining the necessary information which has been carried out recently at Tribophysics.

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Metallurgical Effects of Grain Boundary Ledges

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078225 ◽

1977 ◽

Vol 35 ◽

pp. 126-129

Author(s):

L.E. Murr

Keyword(s):

Grain Boundary ◽

Quantitative Data ◽

Mechanical Treatment ◽

Unit Length ◽

Physical And Mechanical Properties ◽

Direct Observations ◽

Transmission Electron ◽

Properties Of Materials ◽

Thermo Mechanical Treatment ◽

Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

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