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

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