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Significant grain refinement has been demonstrated in many of magnesium alloys [3-5].
The effective deformation per pass according to the von Mises criterion is given by Eq. 2, where N is the number of passages through the dies.
An irregular grain structure of as extruded and annealed sample may indicate that thermally activated process such as dynamic recrystallization and dynamic recovery plays an important role to decrease the average grain size.
Conclusively, room temperature ECAP can improve mechanical property in terms of grain refinement.
Liaw: Ultrafine grained materials II.

To this end, a considerable number of solid-solutions of BFT have been developed in the literature to improve its performance, including BaTiO3 [8], Ba(Zn1/3Ta2/3)O3 [9], and Ba0.06(Na1/2Bi1/2)0.94TiO3 [10].
The grain sizes, and grain shape were discovered using a Carl Zeiss Microscope Ltd., UK make EVO18 scanning electron microscope (SEM).
The average grain size for these solid-solutions was between 1 μm and 20 μm.
Apart from that, it has been discovered that as the concentration of NBT increases, the grain shape and grain sizes of BFT-NBT solid-solutions alter dramatically.
Also, by adding NBT to BFT matrix leads to downsizing the average grain.

On the current efficiency of the sample was calculated, its micro-hardness, tensile strength and stress were measured; and its XRD tests, analysis of the micro-strain, grain size and position electrical castings dislocation density.
Grain size and distribution of dislocations and strength, hardness and fatigue failure between closely related.
In this paper, single-line Fourier analysis method[3,4] for the broadening effect of X-ray diffraction spectra were analyzed draw microscopic strain <ε_L^2> and dislocation density ρ_s, grain size calculated by Scherrer formula.
The data listed in Table 2 is calculated according to the following diagram and the grain size of XRD lattice strain.
Range analysis using the data can not distinguish between the causes of fluctuations due to changes in experimental conditions or due to experimental error, and the various factors on the effects of fluctuations in the size of the data can not give the exact number of estimates, in order to compensate for the lack of range analysis, analysis of variance.

In Figure 2a, when the time interval is 0 s, the microstructure of the test piece had been subjected to the compression deformation of 0.35 by accumulation, so long ribbon structure of crystal grain could be seen obviously along the deformation direction, and small "string-shape" dynamic recrystallization crystal grains were distributed unevenly in the crystal boundary simultaneously.
Elements C Cr Ni N Si Mn S P 304 stainless steel 0.035 18.0 8.1 0.05 0.43 0.95 0.012 0.028 For the dual-interval time interval of 0-5s, tiny crystal grain appeared at grain boundary and interior of the grain due to protruding nucleation, indicating the occurrence of static recrystallization.
It can be seen that the number of the tiny and even crystal grain from the static recrystallization increased obviously in the crystal boundary (Figure 2b).
When the time interval was 10s, the crystal grain of the static recrystallization increased rapidly, producing continue refinement of the crystal grain (Figure 2c).
After the complete static recrystallization, the grain size tended to be stable (Figure 2d).

In that case β modification arises, when we assume the grain shape but it is destructed.
Whereas laboratory prepared samples are characterized in massive prismatic grains, the reference gypsum is very fine-grained because according to all morphology feature it was put to sort by grinding.
Mentioned observing comes to the conclusion that used laboratory vibratory mill is not fundamentally suitable for separation of relatively soft gypsum grains because instead progressive shortening of long prismatic grains, since it resulted in share increasing of submicroscopic particles arising by microscopy grains abrasion of macroscopic grains
That is why for the next works it is suggested to use other type of laboratory mill with different principle of separating which would break prismatic grains than to spread by pressure.
Registration number CZ.1.07/2.3.00/20.0111. and FR-TI2/653 „Komplexní stavební program na bázi vysokohodnotného sádrového pojiva z druhotných surovin“ References [1] FRIDRICHOVÁ, M., KULÍSEK, K., ZELENKOVÁ, R.

The bond tensile strength were obtained by subjecting three numbers of friction stir cladded copper stainless steel joints to ram tensile test for each overlap conditions.
For the samples cladded at 50 % shoulder overlap the much wider zone of DRX austenitic grains around the heavy deformed copper grains.
Moreover, an intercalated pattern of copper grains and austenite grains are observed in the copper deformed zone at the top.
This is mainly due to proper mixing of copper grains with recrystallized austenitic grain and stronger bonding interface.
The extent to which the austenitic grain mixed with copper grains, volume of austenite grains recrystallized around the deformed copper grains, fragmentation of austentic stainless steel particles, micro level defect formation were influenced by the shoulder overlap ratio.

The columnar region consists of elongated grains with a preferred orientation.
In the single phase region (2), from 1.5cm large grain growth occurred upon heating.
Beyond 5.4 cm (7) the morphology of the growing grain structure was equiaxed.
Those models can predict grain structure and CET.
Acknowledgements This work is financially supported by European Commission (contract number NMP-CT-2004500635) Sixth Framework Programme, as the project is co-funded and coordinated by the European Space Agency.

The etched specimens were used to measure the grain size using the Scion Imaging software.
Results of acid dissolution, density, porosity, chemical analysis and grain size measurements.
Number of matching peaks Material CTE x10-6/ 0C Macrohardness (HR15T) Microhardness (HV) Mg SiC Ti Mg2Si Mg 28.02±1.10 47±1 41±1 9[3] -- -- -- Mg/1.1TiP /2.8SiCP 23.41±1.37 48±2 48±1 7[3] 4[3] 2[1] 3[1] Mg/1.1TiP /8.8SiCP 19.91±0.59 65±1 66±1 8[3] 3[3] 3[2] 3[2] [ ] The value in the square brackets indicates the number of strongest peaks matched.
The grain size of the composite samples decreased with increasing amount of reinforcements (see Table 1).
This can be attributed to the ability of reinforcement particulates to nucleate magnesium grains and restrict growth of recrystallised grains by grain boundary pinning.

In micro-forging process, the static and dynamic re-crystallization would take place in the cladding layer and turn into new fine grains.
Size of re-crystallization grain and re-crystallization rate, are not only in relevant with primitive grain size and trace elements outside, but also mainly depend on the deformation and such factors as the temperature, strain and strain rate of cooling process.
Summary on present re-crystallization and grain growth models was shown as below
The average grain size was about 3~4 μm.
Acknowledgements The authors gratefully acknowledge the foundation by the National Natural Science Foundation of China (NSFC) with the project number 50974075.

From sample 3 to sample 7, the number and volume of second phases increase with the Y contents rising.
Those pre-solidifying particles accelerate the nucleation of copper grains for supplying sufficient nucleating center, and then restrict the grains coarsening as a result of binding with grain boundary in the process of grain growth [16].
Therefore, proper Y content refines grains and promotes the forming of dispersing second phases.
This can be attributed to the grain refinement and the second phase strengthening.
Grain size has an important impact on the high-temperature oxidation of metals and their alloys.