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

1972 ◽  
pp. 435-445 ◽  
Author(s):  
Robert E. Green
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
X Ray Diffraction ◽  
X Ray

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.

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" SYNCHROTRON WHITE BEAM X-RAY TOPOGRAPHIC STUDY OF GRAIN BOUNDARY MIGRATION

1990 ◽  
Vol 51 (C1) ◽  
pp. C1-405-C1-414
Author(s):  
J. GASTALDI ◽  
C. JOURDAN ◽  
G. GRANGE
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
X Ray ◽  
White Beam

“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

scholarly journals Cross-Sectional TEM Studies of DIGM in Irradiated Au-Cu Bilayers

1992 ◽  
Vol 279 ◽  
Author(s):  
Yuzun Gao ◽  
Dale E. Alexander ◽  
L. E. Rehn
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Energy Dispersive Spectroscopy ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Cross Sectional ◽  
X Ray ◽  
Small Probe ◽  
Transmission Electron

ABSTRACTCross-sectional transmission electron microscopy was used to study diffusion-induced grain boundary migration (DIGM) in irradiated and annealed Au/Cu bilayers. Using this technique, in combination with small probe X-ray energy dispersive spectroscopy, DIGM alloyed zones in Au were identified in an irradiated sample.

STEM microanalysis of tin segregation in germanium

1983 ◽  
Vol 41 ◽  
pp. 382-383
Author(s):  
C.R.M. Grovenor ◽  
P.E. Batson ◽  
D.A. Smith
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Kirkendall Effect ◽  
Significant Feature ◽  
Grain Boundary Migration ◽  
X Ray ◽  
Left Behind ◽  
Incident Electron Beam ◽  
Vacancy Flux

STEM investigations using very fine incident electron beam diameters and x-ray analysis facilities provide a powerful tool for determining the segregation levels of solute elements at, or near,grain boundaries. As yet however relatively few studies have made use of this potential. It is particularily interesting to apply the technique to the study of Sn segregation to germanium grain boundaries, because the boundaries can be driven to migrate by being heated in the presence of the Sn. It is proposed that this grain boundary migration is caused by a process called Diffusion Induced Boundary Migration, (DIGM). The suggested mechanism for DIGM is that a grain boundary Kirkendall effect occurs due to the uneven fluxes of solute and solvent atoms down the interface. The resulting net vacancy flux stimulates the movement of grain boundary dislocations, which in turn cause boundary migration. A significant feature of this model is that solute enriched grains will be left behind each migrating boundary.

X-Ray Method for Continuous Tracking of Grain Boundary Motion: Investigation of Grain Boundary Migration in Al-Bicrystals

1994 ◽  
Vol 157-162 ◽  
pp. 125-130
Author(s):  
U. Czubayko ◽  
Dmitri A. Molodov ◽  
B.-C. Petersen ◽  
Günter Gottstein ◽  
Lasar S. Shvindlerman
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Motion ◽  
Ray Method ◽  
X Ray ◽  
Grain Boundary Motion

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

Measurement of solute segregation to grain boundaries in the AEM: A review

1988 ◽  
Vol 46 ◽  
pp. 606-607
Author(s):  
D. B. Williams ◽  
A. D. Romig
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Misorientation ◽  
Collector Plate ◽  
Segregation Process ◽  
Grain Boundary Misorientation ◽  
Structure Boundary ◽  
Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

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