Size-dependent reversal of the elastic interaction energy between misfit nanostructures

In this communication, we summarize the current advances in size-dependent continuum plasticity of crystals, specifically, the rate-independent (quasistatic) formulation, on the basis of dislocation mechanics. A particular emphasis is placed on relaxation of slip at interfaces. This unsolved problem is the current frontier of research in plasticity of crystalline materials. We outline a framework for further investigation, based on the developed theory for the bulk crystal. The bulk theory is based on the concept of geometrically necessary dislocations, specifically, on configurations where dislocations pile-up against interfaces. The average spacing of slip planes provides a characteristic length for the theory. The physical interpretation of the free energy includes the error in elastic interaction energies resulting from coarse representation of dislocation density fields. Continuum kinematics is determined by the fact that dislocation pile-ups have singular distribution, which allows us to represent the dense dislocation field at the boundary as a superdislocation, i.e., the jump in the slip filed. Associated with this jump is a slip-dependent interface energy, which in turn, makes this formulation suitable for analysis of interface relaxation mechanisms.

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Elastic Interaction of Defects on Crystal Surfaces

Journal of Engineering Materials and Technology ◽

10.1115/1.2812357 ◽

1999 ◽

Vol 121 (2) ◽

pp. 129-135 ◽

Cited By ~ 8

Author(s):

Demitris Kouris ◽

Alonso Peralta ◽

Karl Sieradzki

Keyword(s):

Interaction Energy ◽

Surface Defects ◽

Film Growth ◽

Crystal Surface ◽

Elastic Field ◽

Elastic Interaction ◽

Flow Mode ◽

Elastic Model ◽

Far Field ◽

Embedded Atom

Surface defects corresponding to adatoms, vacancies and steps interact, affecting and often dominating kinetic processes associated with thin-film growth. A discrete harmonic model for the evaluation of the interaction energy between surface defects is presented. It is based on the concept of eigenstrains and allows for the accurate evaluation of the elastic field, both at the immediate vicinity of the defects, as well as in the far field. Results for the interaction energy suggest conditions for which a body-centered-cubic crystal surface will grow in a stable, two-dimensional, step-flow mode. In order to verify the accuracy of the discrete elastic model, we present results of atomic simulations that incorporate Embedded Atom Method (EAM) potentials. The discrete elastic model results compare favorably with results from our atomic EAM simulations and agree with the far-field predictions of continuum elastic theory.

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The effect of elastic interaction energy on the morphology of γ′precipitates in nickel-based alloys

Materials Science and Engineering ◽

10.1016/0025-5416(84)90056-9 ◽

1984 ◽

Vol 67 (2) ◽

pp. 247-253 ◽

Cited By ~ 125

Author(s):

Minoru Doi ◽

Toru Miyazaki ◽

Teruyuki Wakatsuki

Keyword(s):

Interaction Energy ◽

Elastic Interaction

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Perovskite Ti3AlC Carbide Splitting in High Nb Containing TiAl Alloys

MRS Proceedings ◽

10.1557/opl.2014.950 ◽

2014 ◽

Vol 1760 ◽

Cited By ~ 1

Author(s):

Li Wang ◽

Heike Gabrisch ◽

Uwe Lorenz ◽

Frank-Peter Schimansky ◽

Andreas Stark ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Interaction Energy ◽

Elastic Interaction ◽

Morphological Development ◽

Tial Alloys ◽

Transmission Electron ◽

The Matrix

ABSTRACTTransmission electron microscopy has been used to investigate the morphological development of the perovskite (P-) Ti3AlC carbides in the γ matrix of a Ti-45Al-5Nb-0.75C alloy during annealing. P-Ti3AlC carbides in the γ matrix initially have a needle-like shape but during annealing at 800 °C they change to a plate-like shape. In the needle-like shape the carbides are orientated parallel to the [001] direction of the matrix. They extend along the [100]γ or [010]γ direction into plates later and subsequently split into sub particles after extended annealing. It is proposed that the elastic interaction energy between the split sub domains may be the reason that this decomposition into sub-particles is energetically favorable.

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