106 research outputs found
Low temperature dynamics of kinks on Ising interfaces
The anisotropic motion of an interface driven by its intrinsic curvature or
by an external field is investigated in the context of the kinetic Ising model
in both two and three dimensions. We derive in two dimensions (2d) a continuum
evolution equation for the density of kinks by a time-dependent and nonlocal
mapping to the asymmetric exclusion process. Whereas kinks execute random walks
biased by the external field and pile up vertically on the physical 2d lattice,
then execute hard-core biased random walks on a transformed 1d lattice. Their
density obeys a nonlinear diffusion equation which can be transformed into the
standard expression for the interface velocity v = M[(gamma + gamma'')kappa +
H]$, where M, gamma + gamma'', and kappa are the interface mobility, stiffness,
and curvature, respectively. In 3d, we obtain the velocity of a curved
interface near the orientation from an analysis of the self-similar
evolution of 2d shrinking terraces. We show that this velocity is consistent
with the one predicted from the 3d tensorial generalization of the law for
anisotropic curvature-driven motion. In this generalization, both the interface
stiffness tensor and the curvature tensor are singular at the
orientation. However, their product, which determines the interface velocity,
is smooth. In addition, we illustrate how this kink-based kinetic description
provides a useful framework for studying more complex situations by modeling
the effect of immobile dilute impurities.Comment: 11 pages, 10 figure
Research of problems and technologies for the development scheme of data national standard data transmission for Russian oil & gas companies
Effect of warm to hot rolling on microstructure, texture and mechanical properties of an advanced medium-Mn Steel
The deformation microstructures and mechanical properties were studied in a medium-Mn austenitic steel subjected to warm-to-hot rollin
Grain boundary migration: misorientation dependence
Abstract The ability of grain boundaries (GB) to move has been found to be strongly dependent on crystallography, i.e. misorientation of the adjacent grains and orientation (inclination) of the GB in a crystal. Boundary mobility is rate-controlling in recrystallization and grain growth and thus, affects microstructure evolution and texture formation. This paper deals with recent advances in our understanding of misorientation and inclination dependence of grain boundary migration. © 2001 Elsevier Science Ltd. All rights reserved. A most important peculiarity of grain boundaries is their capillary driven motion technique, in which a curved GB ability to move. This grain boundary (GB) property has moves under the action of GB curvature, and the driving been found to be strongly dependent on grain boundary force p is provided by the GB surface tension g. Since the crystallography, i.e. misorientation of the adjacent grains true value of g is commonly not known, a reduced GB and orientation (inclination) of the GB in a crystal. Boundary mobility is rate-controlling in recrystallization [m / s], i.e. the same as the diffusion coefficient. An and grain growth and thus, affects microstructure evolution inherent feature of GB mobility is that it depends, apart and texture formation. Recent achievements in our underfrom the conventional thermodynamic variables (temperastanding of misorientation and inclination dependence of ture, pressure, etc.), on the misorientation of the adjacent grain boundary migration constitute the subject of this grains and GB orientation. A precise measurement and paper. thus, examination of the misorientation dependence of GB The mobility m is a quantitative measure of the kinetic mobility was made possible by tracking techniques of GB b properties of a grain boundary and thus, the principal migration in bicrystals. The distinctive properties of such parameter of the process of GB migration. It is defined as techniques are: controlled driving force, continuous track-GB velocity v per unit of driving force p: ing of GB displacement, accuracy and reproducibility of GB crystallography [**1]. As a first milestone, from v ] m 5 measurements with these techniques materials scientists b p became aware that properties of GBs with different A driving force for GB migration arises when a boundary misorientation can be essentially different. In particular, it displacement leads to a reduction of the total energy of the was established that GB mobility and its parameters are system. It is necessary to stress that the system need not be changing in a non-motonic way with the angle of mislimited to adjacent grains and a GB only, but may include orientation. external elastic, electrical or magnetic fields as well. There For special misorientations (low-S boundaries) the are two ways by which this driving force arises. The first activation enthalpy H of GB migration assumes a minim uses the free energy of a GB itself, the other utilizes a free mum. An example is shown i
Bericht des Präsidiums 2000 - 2001
The measurement of grain boundary migration in pure Al bicrystals by X-ray continuous interface tracking is introduced. This method provides information on the mobility of specific grain boundaries without interfering with the process of migration. Moreover, the effect of hydrostatic pressure on grain boundary migration was investigated. Several topics of grain boundary motion relevant to microstructure and texture evolution by recrystallization and grain growth were addressed. It was found that the maximum growth rate misorientation changes with temperature from the exact ∑7 orientation relationship to a 40.50°<111> rotation. This behavior is of concern for recrystallization texture evolution. The effect of material purity on grain boundary migration is shown not to be confined to drag effects but also to involve changes of grain boundary structure. From the activation volume of grain boundary mobility it has to be concluded that at least <110> tilt boundaries move by cooperative motion (group mechanism) of atoms in the boundary
Recovery Kinetics in Commercial Purity Aluminum Deformed to Ultrahigh Strain: Model and Experiment
On the role and alteration of grain boundaries in/during accommodating plasticity in magnesium
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