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As a reference, samples of base metal were also analyzed, revealing a homogeneous ASTM grain size number of 8.78±0.17 (corresponding to an average grain diameter of 17.3±1.0µm).
By means of optical microscopy and grain size measurements, this increase is attributed to dynamic recovery and recrystallization, leading to the formation of very fine grains.
In the weld area, measured values of matrix grain size combined with conditions of temperature (around 1200°C at the interface) can reasonably be attributed to grain growth mechanisms.
Fig. 4 - Grain size variation across the weld.
The maximum ASTM grain size number is observed for z=1mm and corresponds to a nominal diameter of 5.6±0.4µm while the base met al value is 17.3±1.0µm. 8 9 10 11 12 0 1 2 3 4 5 6 7 8 Distance from weld (mm) ASTM Grain size number Weld centerline.

The model shows that any increase of static load, size of grain, work speed, number of effective dynamic abrasive particle, the amplitude and frequency of tool or any decrease of fracture toughness property and hardness will result in the increase of the MRR, and the theoretical model of the MRR is tested, meanwhile the paper draws the conclusion that the surface quality under TDUG is superior to that under common grinding, which is tested by the means of grinding of fine-crystalline ZrO2 ceramics.
of effective dynamic abrasive particle, 22K ζ= .� � � � � � � � � � � � � � � � � � � � � �According to Eq.6, any increase of static load, size of grain, work speed, number of effective dynamic abrasive particle, the amplitude and frequency of tool or any decrease of fracture toughness property and hardness will result in the increase of the MRR under TDUG.
It may be the reason that as the speed of working table increases, the friction per unit of time between workpiece and abrasion wheel increases, and the number of effective abrasive particle per unit of time improves.
From Fig.5, MRR is higher when abrasion wheel with coarse grain size is used.
But MRR is lower when abrasion wheel with fine grain size is used, but their change tends with the speed of working table are similar.

The results showed that the threshold led to a higher number of identified grains with lower mean area and total area fraction than the watershed method.
The grain size can be obtained by drawing a line on the image.
Then, the total number of grains within the line is divided by the length of the line [2].
It is expected a certain difficulty in the selection of a grain, or in this case, all the grains of a phase in the image.
There is a white grain in the center of Figure 6-b, a white line indicates the selected area of the grain using thresholding.

It was found that FSW produced an equiaxed fine-grained microstructure in weld zone and the grain size in weld zone decreased up to about 4~6 µm with decreasing rotating speed.
In thermo-mechanical affected zone, the change in grain size was not significant, however, large number of low angle grain boundaries were observed, which seems to be concerned with the formation of subgrains due to the development of dislocation cells.
It is shown that the FSW process produces the reduction of grain size at WZ, whereas the change in grain diameter at TMAZ is not remarkable.
The grain size distributions in WZ are given in Fig. 6.
Fine-grained microstructure was developed in WZ by FSW.

During high-temperature deformation, cavities are produced by stress concentrations at grain boundary triple points and striation bands due to grain boundary sliding.
By using microstructure materials roll formed under a light reduction rate after hot free forging with a small number of passes, the strength of this magnesium alloy at room temperature was ascertained after superplastic deformation was carried out at high temperature.
To examine the effect of grain boundary sliding and intergranular deformation on macroscopic deformation, grain boundary sliding was measured from the shifts angle of scratching lines on the specimen surface.
Deformation under biaxial tensile stress is applied in two directions subject to the grain boundary sliding resistance caused by grain boundary segregation.
This significantly affects grain boundary sliding with a slower strain rate, probably because there are a large number of cavities in the grain boundary triple points.

Fig.2 Typical Raman scattering spectra of Zirconia a)Tetragonal Zirconia, b)Transformed Zirconia (tetragonal + monoclinic) a) b) 800 600 400 200 Wave number (cm -1 ) Intensity (a.u.)
a) b) 800 600 400 200 Wave number (cm -1 ) Intensity (a.u.)
Figure 4 shows the measured relationship between grain size and monoclinic fraction after 150 hrs acceleration test.
Grain size ranged only from 0.2 to 0.3 µm.
Phase stability greatly improved with reducing grain size beyond a threshold value.

The grain is distributed with high-density β″ phases, and the grain boundary phases are spherical and intermittently distributed.
And from a quantitative point of view, β" The number of phases has the highest density.
The kind, morphology, and the number of strengthening phase can effectively affect the final comprehensive properties of the alloy.
To obtain good IGC resistance, the grain boundary is usually required.
At this time, a large number of continuous precipitated phases are produced at the grain boundary, forming a continuous corrosion channel.

As minerals have high plastic anisotropy and a limited number of slip systems GNBs may dominate over incidental subgrain boundaries formed by trapping of statistically stored dislocations.
At high strains the original grains are sub-divided into many smaller domains separated by new high angle grain boundaries.
As most minerals have very high plastic anisotropy and a limited number of independent slip systems GNBs may dominate over incidental subgrain boundaries.
Zones of concentrated deformation occur adjacent to triple points to accommodate grain boundary sliding and deformation compatibility between adjacent grains [43, 45].
In light microscopy studies of experimentally deformed calcite the recrystallized grains were described as having the same size as subgrains in the grain mantles [5].

The average grain size of 7075 aluminum alloy was refined to 12.81μm from 19.62μm at 300℃ for durations of 40min.
Because of grain refinement after annealing, the hardness of base metal increased significantly.
In B point, atomic number ratio between aluminum and magnesium was about 3:2.
In this case, diffusion layer width and grain size were relatively moderate and the joint strength was maximized.
But grain size grew up seriously, large numbers of intermetallic compounds formed.

Internal gettering by EDs including stacking faults and grain boundaries is one possibility.
For the undecorated EDs, the minimum cross-sections defines the number of atoms per atomic plane.
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Gumbsch, "Interstitial iron impurities at grain boundaries in silicon: A first-principles study," Phys.
Yamamoto, "Tight-binding study of grain boundaries in si: Energies and atomic structures of twist grain boundaries," Phys.