Grain boundary mobility under a stored-energy driving force: a comparison to curvature-driven boundary migration

2005 ◽  
Vol 96 (10) ◽  
pp. 1166-1170 ◽  
Author(s):  
M. L. Taheri ◽  
D. Molodov ◽  
G. Gottstein ◽  
A. D. Rollett
Keyword(s):  
Grain Boundary ◽  
Driving Force ◽  
Boundary Migration ◽  
Boundary Mobility ◽  
Stored Energy ◽  
Grain Boundary Mobility ◽  
Curvature Driven

Magnetically Controlled Grain Boundary Motion and Grain Growth in Zinc

2013 ◽  
Vol 753 ◽  
pp. 107-112 ◽  
Author(s):  
Christoph Günster ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Driving Force ◽  
Boundary Migration ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Cold Rolled ◽  
Grain Growth Kinetics ◽  
Grain Boundary Motion

The motion of grain boundaries in zinc bicrystals (99.995%) driven by the “magnetic” driving force was investigated. Planar symmetrical and asymmetrical tilt grain boundaries with rotation angles in the range between 60° and 90° were examined. At a given temperature the boundary migration rate was found to increase linearly with an applied driving force. The absolute grain boundary mobility was determined. The boundary mobility and its temperature dependence were found to depend on the misorientation angle and the inclination of the boundary plane. An application of a magnetic field during the annealing of cold rolled (90%) Zn-1.1%Al sheet specimens resulted in an asymmetry of the two major texture components. This is interpreted in terms of magnetically affected grain growth kinetics.

Grain Boundary Dynamics in High Magnetic Fields. Fundamentals and Implications for Materials Processing

2004 ◽  
Vol 467-470 ◽  
pp. 697-706 ◽  
Author(s):  
Dmitri A. Molodov
Keyword(s):  
Magnetic Fields ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Materials Processing ◽  
High Magnetic Fields ◽  
Boundary Motion ◽  
Grain Boundary Mobility ◽  
Curvature Driven ◽  
Grain Boundary Motion ◽  
Boundary Dynamics

The latest research on dynamics of grain boundaries in non-magnetic materials in high magnetic fields is reviewed. A control of grain boundary migration means control of microstructure evolution, which is a key for the design of materials with desire properties. Grain boundary motion can be affected by a magnetic field, if the anisotropy of the magnetic susceptibility generates a gradient of the magnetic free energy. In contrast to curvature driven boundary motion, a magnetic driving force also acts on planar boundaries so that the motion of crystallographically well-defined boundaries can be investigated, and the true grain boundary mobility can be determined. The results of migration measurements obtained on bismuth and zinc bicrystals are addressed. Selective growth of new grains in locally deformed zinc single crystals driven by a magnetic force is reported as well. Implications for materials processing, in particular the effect of magnetic fields on texture development in hcp metals are finally discussed.

The recrystallization process in some polycrystalline metals

1962 ◽  
Vol 267 (1328) ◽  
pp. 11-30 ◽  
Keyword(s):  
Activation Energy ◽  
Electron Microscope ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Recrystallization Process ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Polycrystalline Metals

Electron microscope observations on some polycrystalline metals suggest that after small to moderate deformation, recrystallization occurs by the migration of the original grain boundaries. A theory based on this mechanism can account for the known form of the recrystallization kinetics without necessarily introducing any anisotropy of grain boundary mobility. For this mechanism the so-called recrystallization activation energy is identical to the activation energy for grain boundary migration.

Effect of Fe Segregation on the Migration of a Non-Symmetric Σ5 Tilt Grain Boundary in Al

2005 ◽  
Vol 20 (1) ◽  
pp. 208-218 ◽  
Author(s):  
M.I. Mendelev ◽  
D.J. Srolovitz ◽  
G.J. Ackland ◽  
S. Han
Keyword(s):  
Grain Boundary ◽  
Interatomic Potential ◽  
Boundary Migration ◽  
Physical Parameters ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Bulk Diffusivity ◽  
Order Of Magnitude ◽  
Effect Of Impurities ◽  
Fe Impurities

We present an analysis, based upon atomistic simulation data, of the effect of Fe impurities on grain boundary migration in Al. The first step is the development of a new interatomic potential for Fe in Al. This potential provides an accurate description of Al–Fe liquid diffraction data and the bulk diffusivity of Fe in Al. We use this potential to determine the physical parameters in the Cahn–Lücke–Stüwe (CLS) model for the effect of impurities on grain boundary mobility. These include the heat of segregation of Fe to grain boundaries in Al and the diffusivity of Fe in Al. Using the simulation-parameterized CLS model, we predict the grain boundary mobility in Al in the presence of Fe as a function of temperature and Fe concentration. The order of magnitude and the trends in the mobility from the simulations are in agreement with existing experimental results.

In Situ Measurements of Magnetically Driven Grain Boundary Migration in Zn Bicrystals

2012 ◽  
Vol 715-716 ◽  
pp. 467-472
Author(s):  
Christoph Günster ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundary ◽  
Activation Enthalpy ◽  
Boundary Migration ◽  
Activation Parameters ◽  
Grain Boundary Migration ◽  
Boundary Mobility ◽  
Exponential Factor ◽  
Grain Boundary Mobility ◽  
Enthalpy Changes

The results of investigations of magnetically driven grain boundary migration in high purity (99.995%) zinc bicrystals are presented. In-situ measurements were conducted by means of a specially designed and fabricated polarization microscopy probe. The migration of planar tilt grain boundaries with various misorientation angles in the range between 60° and 90° was studied. The absolute grain boundary mobility and its temperature dependence was measured in the regime between 330°C and 415°C and the corresponding migration activation parameters were determined. The results revealed that there is a pronounced misorientation dependence of grain boundary mobility in the investigated angular range. The migration activation enthalpy was found to vary between 1.18 eV and 2.15 eV. The obtained activation parameters comply with the compensation law, i.e. the migration activation enthalpy changes linearly with the logarithm of the pre-exponential factor.

Atomic-Scale Simulation of Grain Boundary Kinetics during Recrystallization

2004 ◽  
Vol 819 ◽  
Author(s):  
Z. Trautt ◽  
M. Upmanyu
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Md Simulations ◽  
Atomic Scale ◽  
Stored Energy ◽  
Symmetric Tilt ◽  
Curvature Driven ◽  
Stored Energy Of Deformation ◽  
Boundary Kinetics ◽  
Simulation Time

AbstractWe present two-dimensional molecular dynamics (MD) simulations of symmetric tilt grain boundary kinetics, driven by stored energy of deformation. The latter is introduced by prescribing a well-defined gradient in dislocation density across a flat grain boundary. Bicrystals simulations reveal that the boundary motion, albeit jerky, increases linearly with simulation time. We also employ a control simulation to extract the driving force for motion, which then yields a unique boundary mobility. Preliminary comparisons with curvature driven boundary migration for misorientations 30° and 22.78° suggest that misorientation dependence of boundary migration is significantly less anisotropic, in turn implying that the mechanism of motion itself is different.

Magnetic Field Effect on the Microstructure of Low Silicon Steel

2005 ◽  
Vol 495-497 ◽  
pp. 1165-1170 ◽  
Author(s):  
C.M.B. Bacaltchuk ◽  
G.A. Castello-Branco ◽  
Hamid Garmestani
Keyword(s):  
Magnetic Field ◽  
Grain Boundary ◽  
Driving Force ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Silicon Steel ◽  
Boundary Mobility ◽  
Magnetic Annealing ◽  
Grain Boundary Mobility ◽  
Magnetic Filed

Magnetic annealing at five different magnitudes of field was conducted to evaluate the effect of the field on the recrystallized microstructure of Fe-0.75%Si samples. At higher fields the retardation during recrystallization is compensated by the magnetic filed driving force that causes an increase in the grain boundary mobility of grains that have a certain relationship with the direction of the field

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