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The polycrystal structure is presented by pearlite grains of lamellar morphology (eutectoid mixture of ferrite and cementite in which the both phases have the shape of extended plates) (fig. 2), ferrite grains in the volume of which one can observe the cementite particles of different shapes (subsequently referred to as grains of ferrite-carbide mixture) (fig. 2, c-e), and grains of structurally free ferrite (ferrite grains which do not contain the particles of carbide phase in the volume) (fig. 2, f).
Relative fraction of grains of ferrite-carbide mixture is slightly smaller (from 12% to 65% of steel structure).
In the ferrite of pearlite grains only the first two types of dislocations substructure (substructure of dislocation chaos and netlike dislocation substructure) are observed; the cellular and fragmentary dislocation substructures are revealed only grains of structurally free ferrite and grains of ferrite-carbide mixture. 0,5 μm a b d 250nm c 250nm 250nm f F 0,5 μm e Fig. 2.
TEM image of structure of lamellar pearlite grains (a, b), ferrite-carbide mixture (c, d, e) and structurally free ferrite (f, grain is designated by F); a, c–f – bright-field images, b – microelectron diffraction pattern to (a).
Designations: the first digit – regime number; the second digit – scalar dislocation density in ferrite components of pearlite grains (1); or grains of ferrite-carbide mixture (2) axis – analysis along the center axis; S – from semicircle.

Austenitic grain pattern is observed with Olympus GX71 optical microscope.
Fig.3 Original austenite grain Fig.4 Austenite (deformation temperation =850℃) Figure 3 and 4 show that at the deformation temperation of 850℃, the grain in deformed structure has a tendency of being stretched compared with the original grain, and a slight amount of dynamic recrystallization grains appear near the triple junction and grain boundary.
Compared with the deformed structures the original grain（Figure 3） and at deformation temperation of 950℃（Figure 5）, grains are obviously refined，the dynamic recrystallization area of the deformed structures at strain rate of 1s-1 expands, and the original grain is gradually replaced by dynamic recrystallization grain with the size of newly generated grain enlarging and the number Fig.5 Austenite (deformation temperation =950℃) of cores decreasing.
The dynamic recrystallization behavior occurs more fully in the deformation organization, and the grain boundaries of the stretched original grains become basically obscure, larger grains of dynamic recrystallization being formed in the boundary zone, and being distributed in a homogeneous manner as shown in Figure 5.
Meanwhile the dynamic recrystallization is not complete under lower deformation temperation with newly generated grains mainly concentrated in the area close to the grain boundary of the stretched original grains, the proportion of which being low and the distribution of which being uneven.

The TEM-EDS profiles of (b) and (c) reveal that Lu 3+ ions is present in the grain boundary but not in a grain interior.
(b) Grain Interior Figure 4.
Figure 7 shows a grain boundary in TZP containing 5wt% SiO2 together with the EDS spectra across the grain boundary[23].
Since Zr 4+ and Si4+ ions are tetravalent, the number of vacancies formed near grain boundaries will increase with doping of lower valency cation.
Watanabe, "Grain Boundary Engineering in Ceramics; from Grain Boundary Phenomena to Grain Boundary Quantum Structures" ed. by T.

AghaAli et al. [6] mentioned that grain size number in HAZ is increased corresponded to the number of weld repair that had done on the same location as shown in Fig. 2.
Yet, subsequent heat input due to repeated weld repair will facilitate grain growth and therefore grain size number is decreased.
On the other hand, Vega et al. [9] stated that grain growth is observable in coarse grain HAZ corresponding to the number of repair welding.
Fig. 2 Interrelation between ASTM grain size number in HAZ and number of weld repair [6].
This is because in the first repair new grain is generated and grain refinement is observed, but those grains are started to growth in the following weld repair.

Shaping and flattening diamond grains.
Classification of fabricated diamond grains.
Figure 7 shows a typical feature of diamond grains observed after the truing test.
Thus, an experiment to elucidate the effective truing conditions for forming flat diamond grains was conducted by counting the number of grains categorized into the five types from the total of approximately 350 grains observed in four SEM views obtained by rotating the tool by intervals of 90 degrees.
It was confirmed that crushed grains became detached from the bond face and that the edge of diamond grains became sharp.

He concluded that the annealing of PbS thin film modifies its grain boundaries and consequently increases the grain size.
The increase of solution concentration enhances the reaction rate and contributes towards the increase of number density of planes in all orientations especially towards the preferential orientation (200).
As the deposition time was increased, grains grew bigger while reducing the grain boundaries and overall affecting the mobility of the carriers, thus dropping the resistance.
This variation in results could be attributed to large grain sizes.
It was observed that optical band gap is sensitive to thermal annealing and grain size, it decreases with annealing and increasing grain size.

However, applictions of Mg alloys have been significantly inhibited by low formability inherited from the hexagonally close-packed crystal structure and insufficient number of slip system.
Equiaxed grains were well developed with an average grain size of 19 mm after 2-hour annealing treatment at 430°C, as shown in Fig. 1 (b), which is larger than the typically required grain size of d < 10 mm for grain boundary sliding superplasticity.
The grains in the evenly deformed gauge region, as shown in Fig. 3 (e) and (f), was slightly elongated along the tensile direction and refined with an average grain size of 15 mm.
The grain refinement should be attributed to dynamic recrystallization (DC).
The grain elongation is generally related to dislocaiton creep other than grain boundary sliding (GBS), which is consistant to the relatively large grains in the gauge region, where grain elongation occurs by absorbing or releasing dislocationes.

The first number indicates the SiC content and the numbers after the Al and SiC indicate the average particle sizes.
If N/NoD≈1, the initial number of particles is equal to the number of dilatation steps.
Characteristically such a value is obtained in case if the number of grains decreases quickly under the influence of the dilatation at the beginning.
If the number of grains is N=50…400 in the image, this value will not be changed by some separate particles.
The hardness as a function of a) the RPS b) the Al grain sizes (the number being in front of the SiC indicates its quantity and the number being after it indicates the particle size in µm).

The rapid improvement of fracture strength probably due to the decrease of grain size, pore distribute and the second phase (redundant Si4+ ions) segregating on the grain boundary which enhanced the bond energy of grain boundary.
The addition of SiO2 has significantly effect on grain size.
The increasing of the addition of SiO2 reduced the average grain size which cause the grain boundary phase increased.
Furthermore, the number and distribution of pore in the specimens reduced also enhance the bond energy of grain boundary and result the fracture mode to predominantly transgranular.
Acknowledgements The authors gratefully acknowledge the support of the National High Technology Research and Development Program of China (grant number: 2001AA325030).

The oxide films collected from Al-9.4Si-2.3Cu-1.0Zn-0.49Mg alloy melt were not continuous but contained a large number of particles, as shown in Fig. 3a.
Our previous experiments have demonstrated that melt treatment by intensive shearing prior to solidification can result in significant grain refinement in both Al- and Mg-alloys without any addition of grain refiner [8,14-17].
In practice, in order to enhance heterogeneous nucleation and achieve grain refinement, the nucleation substrate not only needs to be potent, but also needs to have an adequate number density, a consistent particle size and a narrow size distribution [18, 19].
The oxide particles dispersed by melt shearing supply a sufficient number of potent substrates to enhance the heterogeneous nucleation prior to solidification, resulting in grain refinement.
MgAl2O4 particles in the oxide films were dispersed by intensive melt shearing to provide a sufficient number of potent particles for enhancing the nucleation process, resulting in grain refinement.