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I"TRODUCTIO" The capacitance of multilayer ceramic capacitors (MLCCs) can be increased by decreasing the thickness of their dielectric layers and increasing the number of dielectric layers; however, these changes result in low insulation resistance (IR).
BaTiO3-based ceramics also include large grains with grain sizes of approximately 500 nm.
Presence of large grains in dielectric layers The regions with the smaller number of the grain boundaries per dielectric layer are formed due to the presence of large grains.
The number of grains between the electrodes is 4 and 6 in the samples with the 0.8- and 1.2-µm-thick dielectric layers, respectively.
On the other hand, the characteristics of grain boundaries is evaluated from the experimental result of the sample with the 1.8-µm-thick dielectric layer, assuming electric field at the grain boundaries is proportional to the ratio given by (dielectric layer thickness)/(grain boundary width × number of grain boundaries).

The number of forging passes was 10, leading to the total cumulative strain of 4.0.
A number of processing techniques allowing the plastic working up to very large strains at relatively low temperatures including severe deformation at room temperature have been developed and practically utilized.
The total number of forging passes was 10 that resulted in the total cumulative strain of 4.0.
The dotted lines in (c) outline roughly original grains.
Besides twin boundaries, a number of strain-induced (sub)boundaries developed in the initial grains.

These simulation results can not only be used in artificial controlling the grain boundary of nano-grain, but also is of significant for designing new nano-grain with a good grain boundary for structure materials.
Its grain growth and grain volume distribution have a great influence on properties of materials [1].
Results and analysis A number of metals are of Fcc structure, for example, Al, Cu, Au, Ag metals.
Turn to look the grain I and grain II, although the grain boundary between the two grains look like coherence, it still have chink.
The simulation results can be used in artificial controlling the grain boundary of nano-grain and is of significant for designing new nano-grain with a good grain boundary for structure materials.

Table 1 Heat treatment technology for specimens Number Quenching temperature Holding time（h） Number Quenching temperature Holding time （h） 1 850℃ 0.5 17 780℃ 0.5 2 850℃ 1.0 18 780℃ 1.0 3 850℃ 1.5 19 780℃ 1.5 4 850℃ 2.0 20 780℃ 2.0 5 820℃ 0.5 21 750℃ 0.5 6 820℃ 1.0 22 750℃ 1.0 7 820℃ 1.5 23 750℃ 1.5 8 820℃ 2.0 24 750℃ 2.0 9 850℃ 0.5 25 780℃ 0.5 10 850℃ 1.0 26 780℃ 1.0 11 850℃ 1.5 27 780℃ 1.5 12 850℃ 2.0 28 780℃ 2.0 13 820℃ 0.5 29 750℃ 0.5 14 820℃ 1.0 30 750℃ 1.0 15 820℃ 1.5 31 750℃ 1.5 16 820℃ 2.0 32 750℃ 2.0 Results and Discussion Microstructure.
That’s because the ferrites grains would block the growth of austenite.
The grain size of austenite grew up severely when holding time is 2h.
So the grain size in 850℃ grew very clearly.
(2) The grain grow up continuously with the increasing of holding time

This process was repeated until the desired grain size was reached; this was commonly found around 200 µm.
Figure 2: Faceted near-sigma 7 CSL type grains in an HPAl+Zr alloy annealed at 350°C taken at different times to show the growth of recrystallized grains.
Acknowledgments Support is gratefully acknowledged from the Alcoa Technical Center and by the MRSEC program of the National Science Foundation under Award Number DMR0079996.
Humphreys: in Recrystallization and Grain Growth, G.
Shvindlerman: Grain Boundary Migration in Metals: Thermodynamics, Kinetics, Applications (CRC Press, 1999). 7.

The fine-grained structural material was prepared by rapid solidification process. 15 and 30 percent mixture of fine-grained structural material were added to the base alloy to compare these combinations to the alloy which contained no fine-grained structural material.
The average grain diameter d becomes smaller after the addition of 15 percent fine-grained structural material as shown in Fig. 4 (b).
Generally speaking, a larger number of nuclei can facilitate more nucleation events.
Fig. 7 Size of primary silicon in the HCC Al-18%Si alloy billets with addition of different contents of fine-grained structural material There are a number of advantages of grain refinement such as reducing the degree of porosity and the number of the surface defects.
The grain refiner, metastable colloidal particles, in the liquid phase generally slows the growth velocity of newly formed grains, allowing more grains to thereby nucleate.

Therefore, the number of segregating impurities or solutes at the grain boundaries is less than in the case of structure that does not contain subgrains [5,6].
As can be seen, the grain boundary is also enriched in a network of grain boundary precipitates.
This is similar to the grain boundary precipitation of standard 5083AA.
the grain boundaries and hence intergranular corrosion.
Addition of Zn kept precipitation inside the grains, which results in grain boundaries free from precipitate.

The apparent nucleation density (i.e. the number of grains/mm 2) increases with straining.
It is expected that deformation at 700ºC activates a greater number of small nucleation sites than at 740ºC.
The size of ferrite grains varied from 0.2 to 3 µm.
A significant number of iron carbides was observed within the microstructure.
From these micrographs, it could be seen how the growth of new grains is restricted by a significant number of cementite particles surrounding them.

The maximum grain growth rate was observed to be around Nb2O5/CoO = 0.25.
In this case, since the donor additives reduce the number of oxygen vacancies, the diffusivity of the oxygen ions become reduced.
The grain growth of the sintered body can be described by the rate equation )( o n o n ttkRR −=− , where R is the average grain size after heat treatment for time t, Ro is the initial grain size, n is the grain growth exponent and k is the rate constant, inclusive of grain boundary segregation, interface energy (γ) and diffusion coefficient (D) terms [6].
This grain growth behavior can be explained by the occurrence of a solute segregation at grain boundaries since the segregate concentration is hard to obtain.
Another concern about grain growth behavior is grain boundary energy.

Effect of Addition of Some Grain Refiners to Zinc-Aluminum 22, ZA22, Alloy on its Grain Size, Mechanical Characteristics in the Cast and after Pressing by the Equal Channel Angular Pressing, ECAP Adnan I.
Zr has adverse effect on grain refining efficiency resulting in a coarse grain size.
Multi-pass ECAP process to investigate strength, hardness and ductility of commercially used zinc- aluminum alloy (ZA-12) as function of both the applied load and the number of passes was investigated in [9].
The prepared samples were subjected to 1 to 4 pressing then sectioned for examination, it was noted that pressing of Al samples led to the development of the parallel bands of sub-grains and these sub-grains subsequently evolve with further pressing into an array of grains separated by high angle grain boundaries, [10,11].
Effect of the grain refiners on ZA22 micro-hardness.