Investigation of Grain Boundary Migration in Situ by Synchrotron X-Ray Topography

1988 ◽  
Vol 143 ◽  
Author(s):  
C. L. Bauer ◽  
J. Gastaldi ◽  
C. Jourdan ◽  
G. Grange
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Boundary Structure ◽  
Grain Boundary Migration ◽  
X Ray ◽  
Grain Boundary Mobility ◽  
Advantages And Disadvantages ◽  
Grain Boundary Character ◽  
Crystallographic Facets

AbstractGrain boundary migration has been investigated in prestrained monocrystalline specimens of aluminum in situ, continuously and at temperatures ranging from 415 to 610°C by synchrotron (polychromatic) x-ray topography (SXRT). In general, new (recrystallized) grains nucleate at prepositioned surface indentations and expand into the prestrained matrix, revealing complex evolution of crystallographic facets and occasional generation of (screw) dislocations in the wake of the moving boundaries. Analysis of corresponding migration rates for several faceted grain boundaries yields activation energies ranging from 56 to 125 kCal/mole, depending on grain boundary character. it is concluded that grain boundary mobility is a sensitive function of grain boundary inclination, resulting in ultimate survival of low-mobility (faceted) inclinations as a natural consequence of growth selection. Advantages and disadvantages associated with measurement of grain boundary migration by SXRT are enumerated and corresponding results are interpreted in terms of fundamental relationships between grain boundary structure and corresponding migration kinetics.

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.

“In situ” determination of grain boundary migration rates by synchrotron white beam X-ray topography

1988 ◽  
Vol 109 (2) ◽  
pp. 403-411 ◽  
Author(s):  
J. Gastaldi ◽  
C. Jourdan ◽  
G. Grange ◽  
C. L. Bauer
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
X Ray ◽  
Migration Rates ◽  
White Beam

Magnetically Controlled Grain Boundary Migration and Microstructure Evolution in Zn

2013 ◽  
Vol 333 ◽  
pp. 101-106
Author(s):  
Dmitri A. Molodov ◽  
Christoph Günster ◽  
Günter Gottstein
Keyword(s):  
Magnetic Field ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Cold Rolled

The migration of planar grain boundaries induced by a magnetic field was measured in specially grown zinc bicrystals (99.995%). Particularly, symmetrical and asymmetrical <> tilt grain boundaries with rotation angles in the range between 60° and 90° were investigated. Boundary migration was measured in-situ in the temperature range between 330°C and 415°C and the absolute values of grain boundary mobility were obtained. The results revealed that grain boundary mobility essentially depends 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 substantially affected the texture and microstructure evolution. This effect is attributed to the additional magnetic driving force for grain growth arising due to the magnetic anisotropy of zinc.

Measurement of Grain Boundary Migration In Situ by Synchrotron X-Ray Topography

1988 ◽  
Vol 122 ◽  
Author(s):  
C. L. Bauer ◽  
J. Gastaldi ◽  
C. Jourdan ◽  
G. Grange
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
X Ray

Mechanisms of New Orientation Formation during Recrystallization of Old Deformed Aluminium Bicrystals

2005 ◽  
Vol 495-497 ◽  
pp. 1249-1254 ◽  
Author(s):  
Henryk Paul ◽  
Julian H. Driver ◽  
Arnaud Lens
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Pure Aluminium ◽  
Local Orientation ◽  
Sample Heating ◽  
Orientation Mapping ◽  
Grain Orientations ◽  
Slip Planes

The crystallography of recrystallization nucleation has been investigated in channel-die deformed pure aluminium bicrystals with {100}<011>/{110}<001> and {100}<001>/{110}<001> orientations. The new grain orientations and misorientations were followed by systematic local orientation measurements using SEM and semi-automatic measurements in a TEM. In particular, orientation mapping combined with in-situ sample heating was used to investigate the formation and growth of new grains and their crystallographic orientation changes at very early stages of recrystallization. Grain boundary migration and ‘consumption’ of the as-deformed areas was always favoured along directions parallel to the traces of the {111} slip planes that had been most active during deformation. The orientations of the first formed nuclei were misoriented with respect to the orientations identified within the neighbouring deformed areas by α(<111>, <112>, or <100>)relations.

In situ atomistic observation of grain boundary migration subjected to defect interaction

2020 ◽  
Vol 199 ◽  
pp. 42-52 ◽  
Author(s):  
Q. Zhu ◽  
S.C. Zhao ◽  
C. Deng ◽  
X.H. An ◽  
K.X. Song ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Defect Interaction

An Electro-Optical X-Ray Diffraction System for Grain Boundary Migration Measurements at Temperature

1971 ◽  
Vol 15 ◽  
pp. 435-445
Author(s):  
Robert E. Green
Keyword(s):  
Grain Boundary ◽  
Test Specimen ◽  
Boundary Migration ◽  
Aluminum Foil ◽  
Average Diameter ◽  
Absolute Measurement ◽  
Grain Boundary Migration ◽  
X Ray ◽  
Cold Worked ◽  
Considerable Work

Considerable work has been undertaken in order to gain an understanding of the mechanisms responsible for the generation of recrystallization textures developed upon annealing of cold-worked metals. Most direct measurements have consisted of measuring the increase in average diameter of the largest grain growing into a polycrystalline aggregate. Experimental measurements of individual boundaries migrating into deformed single crystals, though of a more fundamental nature, have been made by far fewer investigators. This is probably due to the increased experimental difficulties associated with careful control of such experiments. Most previous investigators have made grain boundary migration measurements by the heat-cool-etch method, despite the fact that it has several marked disadvantages. Other investigators have constructed an X-ray goniometer furnace and used it to measure grain boundary migration rates while the test specimen was maintained at temperature. Since there have been no published reports of the use of such a system in the past thirteen years, it must be concluded that the technique was unsuccessful in general.The system described in the present work is relatively simple in design and extremely simple to use. Not only does it permit absolute measurement of grain boundary position at temperature but it also permits boundary migration measurements to be made of extremely fast moving boundaries. The basic components of the system are as follows. A continuous spectrum X-ray beam is converted by a slit collimating system into a beam which is incident along the entire length of the test specimen. This beam is interrupted by a wire grid just prior to impingement on the test specimen. The test specimen is supported vertically in a furnace maintained at the temperature required for grain boundary migration. The various diffracted X-ray beams pass out of the furnace through a highly reflecting insulating baffle made from very thin aluminum foil and impinge on a fluorescent screen. This screen converts the X-ray image into a visible one which is amplified and recorded using the electro-optical system.

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