Texture Formation in AA5182 Aluminum Alloy by Hot Extrusion

2013 ◽  
Vol 753 ◽  
pp. 497-500
Author(s):  
Kazuto Okayasu ◽  
Hiroshi Fukutomi
Keyword(s):  
Aluminum Alloy ◽  
Boundary Migration ◽  
Hot Extrusion ◽  
Equivalent Strain ◽  
Fiber Texture ◽  
Grain Boundary Migration ◽  
Texture Formation ◽  
Mean Grain Size ◽  
Equivalent Strain Rate ◽  
The Mean

The behavior of texture formation in AA5182 aluminum alloy is investigated by hot extrusion tests under equivalent strain rates and temperatures ranging from 5.0×10-4 s-1 to5.0×10-2s-1 and from 723K to 823K, respectively. After the deformation, {001} (extrusion plane) and {111} double fiber texture is formed in all the deformation conditions. {001} texture develops after the deformation at 823K under equivalent strain rate of 5.0×10-3s-1 up to an extrusion ratio of 2.8. The size of {001} grains is larger than the mean grain size, suggesting that the {001} texture formation is attributed to grain boundary migration. Weakening of {001} texture is confirmed in the annealed section of the specimen.

scholarly journals A model of crystal-size evolution in polar ice masses

2014 ◽  
Vol 60 (221) ◽  
pp. 463-477 ◽  
Author(s):  
Felix NG ◽  
T.H. Jacka
Keyword(s):  
Crystal Growth ◽  
Dislocation Density ◽  
Grain Boundary ◽  
Crystal Size ◽  
Boundary Migration ◽  
Ice Core ◽  
Ice Cores ◽  
Grain Boundary Migration ◽  
Shallow Subsurface ◽  
The Mean

AbstractIn the deep ice cores drilled at the GRIP, NGRIP and GISP2 sites in Greenland and at Byrd Station and the summit of Law Dome in Antarctica, the mean crystal size increases with depth in the shallow subsurface and reaches steady values at intermediate depth. This behaviour has been attributed to the competition between grain-boundary migration driven crystal growth and crystal polygonization, but the effects of changing crystal dislocation density and non-equiaxed crystal shape in this competition are uncertain. We study these effects with a simple model. It describes how the mean height and width of crystals evolve as they flatten under vertical compression, and as crystal growth and polygonization compete. The polygonization rate is assumed to be proportional to the mean dislocation density across crystals. Migration recrystallization, which can affect crystal growth via strain-induced grain boundary migration but whose impact on the mean crystal size is difficult to quantify for ice at present, is not accounted for. When applied to the five ice-core sites, the model simulates the observed crystal-size profiles well down to the bottom of their steady regions, although the match for Law Dome is less satisfactory. Polygonization rate factors retrieved for the sites range from 10–5 to 10–2 a–1. We conclude that since crystal size and dislocation density evolve in a strongly coupled manner, consistent modelling requires multiple differential equations to track both of these variables. Future ice-core analysis should also determine crystal size in all three principal directions.

scholarly journals KINETIC EVOLUTION OF A 3D SPHERICAL CRYSTAL WITH MOBILE PARTICLES USING MONTE CARLO

Anales AFA ◽  
2019 ◽  
Vol Vol.30 (Vol.30 N.2) ◽  
pp. 25-30
Author(s):  
P. I. Achával ◽  
C. A. Rodríguez Luca ◽  
C. L. Di Prinzio
Keyword(s):  
Monte Carlo ◽  
Grain Boundary ◽  
Boundary Migration ◽  
The Other ◽  
Monte Carlo Algorithm ◽  
Grain Boundary Migration ◽  
Initial Radius ◽  
The Mean ◽  
Spherical Crystal ◽  
The Law

In this work, the evolution of a tridimensional (3D) spherical crystal with mobile particles using a Monte Carlo algorithm is presented. The mean radius R of spherical crystal without particles changes according to the law: R2 = -4kt + Ro2, where Ro is the initial radius and k is a crystal constant. However, this law is modified when mobile particles are included. The effect of two types of mobile particles on the grain boundary migration of a spherical grain was also studied. One type of particle remained located in the middle of the grain boundary once it was incorporated (CT), and the other type of particle remained at the grain boundary without having any particular location (NC). It could be seen that the CT particle slowed down more the grain boundary migration than the NC particles. It was also found that the rate of reduction of the grain area is inversely proportional to the concentration of CT particles in the grain boundary for all the CT particles concentrations. Finally, it was established that the grain reaches a limit radius for CT particles which is related to the amount of particles that can be accommodated in the grain boundary.

scholarly journals Grain Boundary Migration and the Texture of Films

1991 ◽  
Vol 13 (2-3) ◽  
pp. 91-99 ◽  
Author(s):  
Idajean M. Fisher ◽  
David A. Smith
Keyword(s):  
Grain Boundary ◽  
Substrate Temperature ◽  
Boundary Migration ◽  
Fiber Texture ◽  
Grain Boundary Migration ◽  
Post Deposition Annealing ◽  
Interfacial Energies ◽  
Amorphous Substrates ◽  
Deposited Films ◽  
Post Deposition

Extensive studies of the microstructure of deposited films establish that grain boundary migration is a ubiquitous process in the development of microstructure and frequently the key process in the formation of a preferred orientation. This conclusion is supported by the interpretation of observations of the structure and orientation of films as a function of substrate temperature and post deposition annealing. Epitaxial deposits can result from oriented nucleation or selective growth processes. On amorphous substrates the anisotropy of the interfacial energies of the deposit results in a fiber texture at temperatures when grain growth occurs either during deposition or in a post-deposition anneal.

Texture Formation by the Compression Deformation of AA5182 Aluminum Alloy at High Temperatures

2012 ◽  
Vol 715-716 ◽  
pp. 918-923
Author(s):  
Hyeon Mook Jeong ◽  
Kazuto Okayasu ◽  
Hiroshi Fukutomi
Keyword(s):  
Boundary Migration ◽  
High Stress ◽  
Fiber Texture ◽  
Pole Density ◽  
Texture Formation ◽  
High Stress Region ◽  
Stress Region ◽  
Ebsd Technique ◽  
Region 10 ◽  
Main Component

Texture formation of AA5182 for compressive deformation with a range of temperatures from 673K to 823K and strain rates from 5.0×10-4to 5.0×10-2s-1is experimentally investigated by EBSD technique and X-ray diffraction. Fiber textures are observed in all deformation conditions. Stress regions are divided into a low stress region (10~55MPa) and a high stress region (above 55MPa) on the basis of the relationship between stress and grain size. In the low stress region, it is found that the main component of the fiber texture is {001}(compression plane). In this case, the pole density at {001} is increased with increasing temperature at the same stress level. It is concluded that development of {001} component is attributed to grain boundary migration. For the high stress region, the main component of the fiber texture is {011}. It is considered that the formation of {011} component is attributed to the slip deformation by {111}<110> system.

Effect of Doping and Oxidation on Grain Growth in Polysilicon

1981 ◽  
Vol 5 ◽  
Author(s):  
David A. Smith ◽  
T.Y. Tan
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Point Defects ◽  
Boundary Migration ◽  
Chemical Vapor ◽  
Grain Boundary Migration ◽  
Transmission Electron ◽  
Mean Grain Size ◽  
Chemical Vapor Decomposition ◽  
Phosphorus Doped

ABSTRACTWe have studied the influence of doping and oxidation on grain growth of small grain polysilicon. Intrinsic and phosphorus doped (to 1021 /cc pseudo-amorphous layers of Si were prepared by chemical vapor decomposition of SiH4 at 600°C on thermally grown SiO2 on Si wafers. These samples were then annealed in N2 or O2 ambients at 1000°C for 30 minutes. Transmission electron microscopy examination of the samples revealed that grain boundary dislocations were commonly present at high angle boundaries and that there was a remarkable disparity in mean grain size, d, for the different samples. It was found that d was greater for (a) doped poly than intrinsic poly annealed in either N2 or O2, and (b) for the same polysilicon starting materials (doped or undoped) annealed in O2 than in N2. We propose that these phenomena may be explained by the influences of dopant and point defects on grain boundary dislocation mobility which in turn governs grain boundary migration. An atomistic model of grain boundary migration has been developed. A key aspect of the model is the formation and motion of jogs and kinks on grain boundary dislocations. These processes are directly influenced by the behavior of point defects in the material and its electronic properties.

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.

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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