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The grain size of hcp matrix was about 1µm, indicating that remarkable grain refinement was occurred by extrusion since the grain size of as-cast alloy was about 500µm.
Special attention has been paid on the enrichment of solutes at stacking faults and grain boundaries in the fine-grained matrix, which would contribute not only to the strengthening but also to the stability of fine-grained structure because of its role of an inhibiter against grain coarsening.
In the case of Mg alloy, in addition to this contribution, ductility is improved by grain-refinement because of the increase of the number of independent slip systems activated.
The extruded alloy consisted of the dispersed block of LPSO phase and the fine-grained matrix with the grain size around 1 µm.
HAADF-STEM images exhibited that Zn or Y were enriched at grain boundaries and stacking faults inside the grains in the matrix, which would increase the thermal stability of the fine-grained structure.

One is “intragranular” grain, which exits in the alumina grain and the number is less.
The other is “intergranular” grain, which exits among the alumina grains and the number is larger.
One is “intragranular” grain[10,11], which exits in the alumina grain and the number is less.
The other is “intergranular” grain, which exits among the alumina grains and the number is larger.
One is “intragranular” grain, which exits in the alumina grain and the number is less.

The average as-deposited copper grain size was 5 µm.
Grain boundary slipping and the dislocation movement coordinating grain boundaries spur the grains rotation and translation.
As the sizes and shapes of grains are diversiform and the dislocation phase within the grain are irregular, , contact stress with oscillating character among the rotating-translating grains are excitated on the contiguous grain boundaries, and the dislocations arise too.
TRV-I TRV-II Fig.6 Schematic diagram of the interacting between two adjacent vortexes →o active dislocation sources →× potential dislocation sources As the vortexes include different number of grains, the grains sizes and shapes also affect the volume and space-time character of vortexes.
In this mechanism, grain boundary slipping and the dislocation movement spur grains rotation and translation.

So this high load level of microscopic compressive stresses of the (11-20) oriented grains and the increase in these microstresses with increasing number of cycles supports the increasing twinning of this grain fraction.
Due to the larger grain sizes present in series A, the increase in defect density with increasing number of cyclesis not sufficient to reduce the twinning / detwinning activity. 4.
The increasing defect density hinders the detwinning so that the fraction of stable daughter grains increases with the number of cycles.
However, under compression the fraction of twinned grains increases with the number of cycles due to the high microstresses of the (11-20) oriented grains.
Due to the larger grain sizes in the microstructure of series A, the increase in defect density with increasing number of cycles is not sufficient to provide an increase in hardening in the compression regime.

Ultrafine-grained (UFG) and nanostructured metals have a notable increase in strength compared to conventional coarse grained metals due to the grain boundary strengthening effect.
A arge number of SPD methods have been proposed in order to obtain UFG materials during the last three decades.
The processing method has a major impact not only on grain refinement level but also on many other characteristic microstructural features, such as grain shape, the direction of grain elongation, grain size distribution and density of dislocations.
There is a clear dependence between grain size and applied strain – the higher strain, the smaller the grain size.
It has been proved that the processing route has the major impact on the average grain size, grain size distribution, grain shape and the distribution of grain boundary misorientation angles.

The samples all exhibit uniform microstructures with equiaxial grains as shown in Table 1 Summary of microstructures, composition, and dielectric properties of the samples Sample Grain size (nm) No. of GB with NP* Ba/Ti Bi/Ti Sr/Ti εeff (x104) tgδ(%) T1 T2 T3 280 ±120 2300±925 290 ±140 - 49/204 35/229 0.071±0.084 0.106±0.010 0.147±0.085 0.012±0.006 0.012±0.005 0.011±0.010 0.940±0.110 0.892±0.044 0.872±0.093 4.2 39 37 23 5 3 * Given as ratio against the total number of observed GB.
However, significant grain growth happened in sample T2 compared to the sample T1 and T3 as indicated by the cumulative distributions of grain size in these samples (Fig. 1b).
The data of average grain sizes are also listed in Table 1.
The number of GB decorated with NP is different in the T2 and T3 samples: the percentage of such GB decreases from about 25% in T2 to 15% in T3, as also listed in Table 1.
McLean: Grain Boundaries in Metals.

The effective diffusivities derived from both sections are more than 2 orders of magnitudes higher than the grain boundary diffusivities in coarse-grained Cu.
Recently, investigations on the diffusion in an ultrafine-grained Cu-Zr alloy produced by equal channel angular pressing (ECAP) showed two kinds of short-circuit diffusion paths: one was associated with the "non-equilibrium" GBs containing a large number of dislocations and defects and the other one corresponded to the relaxed high-angle GBs (HAGBs) [3].
The variation of the grain/cell size with the depth is summarized in Fig. 1(b).
As described previously, NS grains in the top surface layer are formed by the "cutting" of nanometer-thick twin-matrix lamellae by dislocations and a large number of interfaces in the top surface layer are expected to originate from TBs.
In the top layer of ~10 m in thickness, the grain size is in the range of 10-25 nm and a large number of interfaces are developed from TBs.

This resulted in an equiaxed grain size of 68 ± 4 µm.
As annealing proceeds the recrystallising grains grow into the non-banded grains.
Discussion From Fig. 2 it appears that nucleation of recrystallisation takes place preferentially at grain boundaries and inside grains with well developed microband structures.
The number of subgrains per unit volume α (δ) -3, and, assuming that the shapes of recrystallised grains and subgrains are the same, means that, from equation (5), the probability of a subgrain forming a nucleus increases somewhat with decreasing subgrain size.
If these were the only sites, one should consider only the number of subgrains impinging on boundaries.

The objective of this work is to discriminate single corn kernel and some broken kernels, which are difficult to achieve on the existing machinery and equipment, especially for the counted number and quality inspection process.
ENg ，W.F.Wilcke used three-layer neural network to research the detection techniques of grain damage and moldy maize grain [2]; in 2008, Shi Zhixing, Cheng Hong etc.
Based on the Matlab environment, through statistical analysis of a large number of corn kernels image, we can extracted a threshold of Area from the image [7].
Type 0 for broken kernel, 1 full grain, large amounts of data were normalized to train the model.
It was concluded that this may be used for variety and quality testing equipment for masses of grain.

The number of lattice points in the FDM is 256 ×256, and nodes in FEM is 6156.
The number of nuclei decreaces with increase of number of additional elements.
Grain diameters are calculated on the basis of the number of finite element included in each recrystallized grain.
The number of grains whose diameters are less than 0.4 µm is biggest in the case of .
It is obvious that more additional elements keep grains from recrystallizing, and the number of recrystallized grains become smaller.