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Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities.
Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities.
The volume fraction is 0.0026% and the number density is 0.0463 mm-3.
S9 (a) Band contrast (BC), (b) inverse pole figure taken from only the secondary α-Al grains, and (c) the number fraction of the secondary α-Al grains in the long thin samples with a relatively higher cooling rate produced by Al-7Si-0.3Mg based alloy with the recycled secondary materials of 20 % (F).
S11 Band contrast (BC), (b) inverse pole figure taken from only the secondary α-Al grains, and (c) the number fraction of the secondary α-Al grains in the large thick samples with a relatively lower cooling rate produced by Al-7Si-0.3Mg based alloy with the addition of recycled secondary materials of 30 % (H).

The rotating bending processes carried out with various conditions show that the grains in cross-section and longitudinal section of magnesium alloy tube were refined for all samples by the rotating bending process with rotation speed of 20r/min for different rotation numbers and temperatures.
It can be seen that the grain number increased significantly in the relative area after rotating bending process.
After plastic deformation at low temperature region (150 and 200°C), the dense dislocation piled up in the interior of grains accompanied by the forming of a large number of twins.
The average grain size was reduced due to the newly formed fine grains.
As the grain size is small, the strong deformation had little effect of on the grain shape as well as grain boundaries.

Such nanocrystalline electrodeposits are in thermodynamically non-equilibrium (metastable) states, i.e. high energy states due to a large number of interfaces [8-10].
Since nanocrystalline materials are in high energy states due to a large volume fraction of the interfacial components such as grain boundaries and triple junctions, the driving force for grain growth is so large that the grain boundaries can move far below temperatures at which grain growth is expected to occur in coarse-grained materials.
Gray-colored grains indicate the <100>//ND grains.
The activation of grain growth may depend on the crystallographic orientation of each grain as-deposited, and it is obvious that the growth rate of the <111>//ND grains is highest.
Thus, what should be explained is why the abnormal grain growth occurs selectively for the <111>//ND grains.

The alloy shows typical equiaxed b grains with second phase precipitation and twin formation inside the b grains in the as-rolled condition.
Solution treatment at lower temperature led to a smaller b grain size while higher temperature solution treatment produced coarse grains with increasing precipitated phases inside the β grains.
After double solution treatment and ageing, the alloy has an increasing number of α phase particles at the grain boundaries, locally connected like a pearl necklace and a further coarsened β phase structure as shown in Fig. 1d.
For the solution treated and aged sample, thermal exposure increased the β grain size and the number of precipitates appearing within the grains.
Funkhouser, Coating for prevention of titanium combustion, NASA report number CR-165360, 1980

When the internal oxidation reaches to 1000℃, the matrix grains begin to appear annealing twins.
The metallic oxide particles exist diffusely in the matrix grains with equixial shape.
With the increasing of the internal oxidation temperature, the grains grow up obviously.
When the internal oxidation temperature reaches to 1000℃, the matrix grains begin to appear twins.
The arc erosion surface shows a large number of paste-like coagulum and bubbles.

Experimental results and analysis Metal crystals can be regarded as a composition by grains and grain boundaries; grain boundary is the 2-d defects in metal.
It separates grain to two different interfaces.
Table 2 Austenite grain size were examined by oxidization and grain boundary etching method grade of steel Austenite Grain Size with Oxidizing Method Austenite Grain Size with grain boundary etching method level mean chord length (mm) level mean chord length (mm) 20 6(85%)+7(20%) 0.0322 6(85%)+7(15%) 0.0334 20CrMo 7(80%)+8(20%) 0.0248 7(80%)+6(20%) 0.0285 20Cr2Ni4 8～9 0.0174 7(80%)+8(20%) 0.0243 40Cr 9～10 0.0115 8～9 0.0182 45 6(50%)+8(50%) 0.0284 6(50%)+8(50%) 0.0287 In addition, because Ti6Al4V (TC4) belongs to alpha and beta dual phase titanium, so usually, TC4 has two phases, i.e. alpha and beta phases.
The grain size of TC4 alloy is large, when high-speed cutting, since cutting thickness is less than the grain size; there is a great risk of cutting off the grain in the cutting process.
From microstructure analysis, TC4 (Ti6Al4V) alloy is dual phase alloy, with high strength and low plasticity due to its low number of sliding systems.

The solution with the greatest number of votes is deemed the most likely.
Comparisons are then made of the number of observed spots in the RDP with those predicted in a simulation of the pattern using the mean orientation.
Numerous studies have been made using the DFC procedure to form OIM images on a large number of materials most of which were single-phase materials.
The number of spots observed was also less than what was seen in a selected are diffraction pattern recorded from the same area.
Hence grain map 6b is a better representation of the grain contiguity than that shown in figure 6a.

The HPT made samples exhibit ultra fine grained (UFG) structure with grain size around 100 nm.
Recently it has been demonstrated that ultra fine grained (UFG) metals with grain size around 100 nm can be produced by high pressure torsion (HPT) [2].
A number of UFG metals exhibit favorable mechanical properties consisting in a combination of a very high strength and a significant ductility.
Results and Discussion Coarse-Grained Specimens.
Similar behavior of HV was observed also in HPT deformed Cu [9] and it seems to be typical for a number of HPT deformed metals.

In the present work, results are presented which illustrate both the role of grain orientation and grain boundaries in the corrosion process.
Not only the role of the grain orientation will be investigated, but also the role of the grain boundaries will be taken into account.
From the IPF map (Fig. 1b), it was observed that grain 1 and 3 have an orientation close to <001> // ND while grain 2 is oriented close to <111> // ND and grain 4 has a near <112> // ND orientation.
Three line scans between grain one and two determine the average height difference between these grains (c).
When comparing the FE-SEM view in Figure 5a with the image quality map in Figure 5b, which depicts the different types of boundaries, a number of observations can be made.

Severe Plastic Deformation (SDP) processes including Hydroextrusion (HE) causes the change of the mechanical properties by the introduction of a large number of defects and significant refinement of the microstructure.
Only after a certain deformation, grains become more equiaxed.
Grain size distribution was determined using the program Micrometer .
They are most frequently mentioned two characteristics which influence the corrosion resistance: chemical homogeneity and a large number of defects in the structure of the grain boundaries.
Hydrostatic Extrusion resulted in impaired grain structure.