Grain boundary migration during room temperature deformation of nanocrystalline Ni

2006 ◽  
Vol 55 (8) ◽  
pp. 695-698 ◽  
Author(s):  
Diana Farkas ◽  
Anders Frøseth ◽  
Helena Van Swygenhoven
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Boundary Migration ◽  
Temperature Deformation ◽  
Grain Boundary Migration

scholarly journals Development of microstructure in the high-temperature deformation of ice

1996 ◽  
Vol 23 ◽  
pp. 293-302 ◽  
Author(s):  
Christopher J. L. Wilson ◽  
Yanhua Zhang
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Time Lapse ◽  
Grain Structure ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Boundary Migration ◽  
Crystallographic Slip ◽  
Polycrystalline Ice ◽  
Time Lapse Photography

Microstructural changes in three sets of experiments involving crystallographic slip in anisotropic polycrystalline ice are described and interpreted with the aid of computer models. The development of microstructure was followed using time-lapse photography and transmitted light observations with deformation undertaken in plane strain and at a temperature of approximately –1°C. The deformation within a grain aggregate that accompanies axial shortening is always heterogeneous on a grainscale. The extent of inhomogeneity varies depending on the pre-existing grain structure and the way it can accommodate intragranular slip. Grain interactions are extremely important in determining the bulk deformation and the degree of grain-boundary migration. A consequence of shortening of the aggregate is the formation of high stresses between neighbouring grains and under the appropriate conditions there may be either grain-boundary migration or melting at these sites. Where a sample undergoes translation and shear during deformation, anisotropic grains in the appropriate orientation undergo bending. A buckle instability may then develop and much of the strain is accommodated by grains in easy-glide orientations. In such situations, the ice undergoes extensive recrystallization and grain growth that is concentrated in the areas of greatest buckling.

scholarly journals Development of microstructure in the high-temperature deformation of ice

1996 ◽  
Vol 23 ◽  
pp. 293-302 ◽  
Author(s):  
Christopher J. L. Wilson ◽  
Yanhua Zhang
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Time Lapse ◽  
Grain Structure ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Boundary Migration ◽  
Crystallographic Slip ◽  
Polycrystalline Ice ◽  
Time Lapse Photography

Microstructural changes in three sets of experiments involving crystallographic slip in anisotropic polycrystalline ice are described and interpreted with the aid of computer models. The development of microstructure was followed using time-lapse photography and transmitted light observations with deformation undertaken in plane strain and at a temperature of approximately –1°C. The deformation within a grain aggregate that accompanies axial shortening is always heterogeneous on a grainscale. The extent of inhomogeneity varies depending on the pre-existing grain structure and the way it can accommodate intragranular slip. Grain interactions are extremely important in determining the bulk deformation and the degree of grain-boundary migration. A consequence of shortening of the aggregate is the formation of high stresses between neighbouring grains and under the appropriate conditions there may be either grain-boundary migration or melting at these sites. Where a sample undergoes translation and shear during deformation, anisotropic grains in the appropriate orientation undergo bending. A buckle instability may then develop and much of the strain is accommodated by grains in easy-glide orientations. In such situations, the ice undergoes extensive recrystallization and grain growth that is concentrated in the areas of greatest buckling.

Effect of Grain Boundary Migration on Texture Formation in Al-3mass%Mg Solid Solution during High Temperature Deformation

2007 ◽  
Vol 558-559 ◽  
pp. 551-556 ◽  
Author(s):  
Kazuto Okayasu ◽  
Hiroki Takekoshi ◽  
Hiroshi Fukutomi
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Fiber Texture ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Boundary Migration ◽  
Strain Rates ◽  
Main Component

Uniaxial compression deformation is conducted on solid solution Al-3mass%Mg and Al-3mass%Mg-0.2mass%Sc with Al3Sc precipitates in the strain rates ranging from 1.0×10-4s-1 to 5.0×10-3s-1 at 723K. High temperature yielding is observed. Fiber texture is constructed in all the deformation conditions. While the main component of the fiber texture changes from {011} to {001} in Al-3mass%Mg alloy with an increase in strain rate, no big change in texture main component is seen for Al-3mass%Mg-0.2mass%Sc alloy with Al3Sc precipitates. It is experimentally shown that the development of {001} fiber texture can be attributed to the grain boundary migration.

In situ studies on grain boundary migration in ceria-stabilized TZP

1990 ◽  
Vol 48 (4) ◽  
pp. 192-193
Author(s):  
Herbert K Schmid
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Room Temperature ◽  
Boundary Migration ◽  
Tetragonal Zirconia ◽  
In Situ Tem ◽  
Grain Boundary Migration ◽  
Thin Foils ◽  
Prepared State

Tetragonal zirconia polycrystals (TZP) have become of interest due to their exceptionally good combination of mechanical properties. In a previous study the microstructure/microchemistry of grain boundaries (GBs) in CeO2 stabilized ZrO2 (Ce-TZP) was investigated and evidence was found on the existence of vitreous ana crystalline intergranular phases in these ceramics. Recently, the observation of wavy GBs in ceria-zirconia was reported. This phenomenon was attributed to diffusion-induced grain boundary migration (DIGM). In the present work, the in-situ TEM observation of GB migration in Ce-TZP, nominally at room temperature, is reported.Thin foils for TEM observations were prepared from a Ce-TZP ceramic nominally composed of 90 mol% ZrO2 plus 10 mol% CeO2 and were examined in a Philips EM 420 analytical STEM, operated at 120 kV. Grain boundaries were observed to migrate in specimen areas exposed to extensive electron irradiation during TEM experiments. The micrograph in Fig. 1 shows a BF image of a triple grain junction (TJ) area in the as-prepared state.

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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