Journal ArticleDOI
The Orowan mechanism in anisotropic crystals
R.O. Scattergood,David Bacon +1 more
TLDR
The static equilibrium configurations of a dislocation bypassing a periodic row of impenetrable circular obstacles were obtained for various crystals by means of a self-stress method wherein the elastic anisotropy of the crystal and the dislocation self-interaction could be taken into account.Abstract:
The static equilibrium configurations of a dislocation bypassing a periodic row of impenetrable circular obstacles were obtained for various crystals by means of a self-stress method wherein the elastic anisotropy of the crystal and the dislocation self-interaction could be taken into account. A correlation was developed from the results which related the Orowan stress values to the obstacle size and spacing. This correlation demands two parameters to account for the anisotropy, and these appear as a suitably defined anisotropic shear modulus and Poisson's ratio. The self-interactions are taken into account by a single logarithmic parameter which is the harmonic mean of the obstacle size and spacing, and is independent of anisotropy. The shapes of the bowing dislocation loops are strongly influenced by the anisotropy and interactions. The combined effects on shape can bo simply described in the line-tension framework, using the de Wit—Koehler solutions. In particular, the swept areas and overall ...read more
Citations
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Journal ArticleDOI
Energy barrier for homogeneous dislocation nucleation: Comparing atomistic and continuum models
TL;DR: In this article, the authors compare the energy barriers predicted by continuum mechanics models for homogeneous dislocation nucleation in copper with explicit atomistic calculations and find that a relatively simple continuum model can agree with full atomistic calculation if the dislocation Burgers vector is allowed to increase continuously during nucleation.
Journal ArticleDOI
A Multiscale Model of Plasticity Based on Discrete Dislocation Dynamics
TL;DR: In this article, a framework coupling continuum elasto-viscoplasticity with three-dimensional discrete dislocation dynamics is presented, where the elastic response is governed by the classical Hooke's law and the viscoplastic behavior is determined by the motion of curved dislocations in a 3D space.
Journal ArticleDOI
Soft computing techniques in advancement of structural metals
TL;DR: In this article, the contribution of soft computing in the field of structural metals and alloys including processing and joining has been discussed, and the critical issues concerning applicability of particular techniques in specific materials problem have been particularly emphasised encompassing the...
Journal ArticleDOI
Dislocation climb effects on particle bypass mechanisms
Yang Xiang,David J. Srolovitz +1 more
TL;DR: In this article, the effects of dislocation climb on the mechanisms by which dislocations bypass particles are examined based upon three-dimensional, level-set, dislocation dynamics simulations that include all elastic interactions, dislocations glide, cross-slip and climb, and particles that are either impenetrable or penetrable and either with or without misfit.
Journal ArticleDOI
Creep mechanisms of ferritic oxide dispersion strengthened alloys
Anna Wasilkowska,Martin Bartsch,Ulrich Messerschmidt,R. Herzog,Aleksandra Czyrska-Filemonowicz +4 more
TL;DR: In this article, a study of creep mechanisms of ferritic ODS alloys was performed based on high temperature tensile/compression tests combined with electron microscopy analysis of deformed specimens and in situ observations of dislocation motion under stress.
References
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Book
Theory of Dislocations
John Price Hirth,Jens Lothe +1 more
TL;DR: Dislocations in Isotropic Continua: Effects of Crystal Structure on Dislocations and Dislocation-Point-Defect Interactions at Finite temperatures.
Journal ArticleDOI
The effect of dislocation self-interaction on the Orowan stress
TL;DR: In this article, the effect of dislocation self-interaction on the Orowan stress was determined for collinear, impenetrable circular obstacles, and an appropriate integro-differential equation governing static equilibrium was solved by an algorithm based on curvature adjustments.
Journal ArticleDOI
The self-stress of dislocations and the shape of extended nodes
TL;DR: In this article, a definition of the self-stress of a dislocation is proposed which is closely related to the more usual notion of a line tension, enabling a numerical calculation to be made of the shape of extended nodes in dislocation networks, and such a calculation leads to revised values of stacking-fault energies of alloys.
Journal ArticleDOI
Interaction of Dislocations with an Applied Stress in Anisotropic Crystals
G. deWit,J. S. Koehler +1 more
TL;DR: In this article, the equilibrium shape of a dislocation segment between two pinning points in the same glide plane is calculated using an energy per unit length, which is a function only of the angle between the Burgers vector and the tangent to the dislocation.