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Size of microvoids deduced from τ2 is represented in the last column as corresponding number of vacancies nV (see text for details).
grain interiors, was found by TEM in UFG Cu and Fe as well.
A large number of vacancies is created during SPD.
Microvoids (small vacancy clusters) are formed inside grains.
Number of defects in HPT deformed sample decreases with depth in certain surface layer.

Therefore, different authors have concentrated on determining the active number of cutting edges.
(9) Hence, the total number of grains Ng,tot on the side surface of the core drill (da = outer diameter, di = inner diameter of the drill) can be calculated: (10) Two grain distributions are assumed.
Trajectories in phase (Figure 9) occur when the length of an ultrasonic vibration in tangential direction exactly corresponds to a whole-number multiple of the tangential grain distance.
Since the results change with the radius due to the different number of grains on each radius, calculations need to be conducted for each radius and averaged.
The material removals have to be multiplicated with the US-frequency and the number of grains on the front surface of the tool to obtain a microscopic material removal rate MRRmi (Eq. 13).

In recent years, people have proposed a number of model against RBAC, such as RBAC96[1], ARBAC97[2], ARBAC02[3], RHA4[4] and HARBAC[5] etc.
In Section 2 we present the proposed fine-grained RBAC model.
In this paper, we propose the fine-grained RBAC model as follows: 1.
Fine-grained RBAC requires fine-grained resources; therefore the proposed RPA can identify access control by URI resources.
Class diagram of fine-grained RBAC architecture.

The results of microstructure shows that the second phase particles pinned on grain boundary not only can inhibited the grain growth, but also the grain can be fined during the heating and cooling course.
The numbers of precipitates decrease greatly in the center of sample.
Fig.3 The particle pinning on grain boundary The effect of the second-phase particles on the grain refinement.
The second particles which are shown on the fig.4(b) is dispersed on the matrix and present irregular ellipse, but the numbers of second particles is less than that of on the fig.4(a) .
On the other hand, the ferrite grain can be fined during cooling by the second-phase particles pinned on the ferrite grain boundary.

Vickers Hardness Numbers (HV) calculated from a minimum of 240 indentations made across the SZ of each sample were presented as microhardness distribution contour maps.
Significant grain refinement can be observed in the SZ, as shown in Fig. 2b.
Table 3 Summary of the average grain sizes and mechanical testing results for AZ91 alloy.
Apart from that, the horizontal microhardness profiles plotted in Fig. 5 not only illustrate higher Vickers Hardness numbers within the SZ (dashed box region), but showed general uniformity in the microhardness across the SZ, as opposed to the high fluctuations observed in the outer, unstirred region.
Significant grain refinement from an average grain size of 123.1 μm to about 5.0 to 6.2 μm was achieved.

BLSFs have the general formula (Bi2O2) 2+- (Am-1BmO3m+1) 2, in which pseudoperovskite (Am-1BmO3m+1) 2 layers are interleaved with (Bi2O2) 2+ layers, where m is the number of BO6 octahedra in the pseudo-perovskite layers (m = 1 to 5).
There are several possible ways, such as Hot-Forging (HF) method and Templated Grain Growth (TGG) method, to obtain grain oriented samples.
Grain-oriented samples were prepared by the hot-forging (HF) method � [5].
The grain-oriented factor, F, was calculated using the Lotgering method [7].
This is due to the grain orientation.

A large number of investigations have examined the effect of different deformation and annealing conditions (temperature and time).
For the grain size measurements, both the average size of all grains, and the average size of only the grains with orientations within 15 o of <001>{100} were determined.
The solid line is the average value for annealing without magnetic field. 0 10 20 30 40 50 60 70 80 90 8 12 16 20 24 28 Grain size (µµµµm) Angle to magnetic direction cube grain size all grain size Figure 4.
The results suggest that the presence of the magnetic field results either in retardation of grain growth, or in an increase in the number of recrystallization nuclei.
Acknowledgements This work was supported by the National Natural Science Foundation of China under contract numbers 50474087 and 50231030.

Through long distance migration of its high angle grain boundary after nucleation, the recrystallized grain usually grows to tens of micrometers.
Shih et al [32] and Torre et al [33] also observed similar softening phenomenon in yield strength in ECAP processing of Oxygen Free High Conductive (OFHC) copper. 0 4 8 12 16 20 24 2.5 3.0 3.5 4.0 4.5 5.0 5.5 99.98 wt% Cu ECAP at RT ECAP Load, T Number of ECAP Passes 0 4 8 12 16 20 24 0 90 180 270 360 450 0 10 20 30 40 50 60 Yield Strength 99.98 wt% Copper ECAP at R.T.
Tensile Yeild Strength, MPa Number of ECAP Passes Elongation, % Elongation Fig.1 Dependence of yield stress and elongation upon ECAP passes.
A relatively well-defined recovered grain was seen in figure 5(a), to the left of the triangular grain, well developed grain boundary with fringes was observed condensing out from grain boundary dislocations extending far into the interior of the neighboring grain (crystal fragment), as shown by the white arrows in the figure.
Figure 5(b) shows local (sub-) grain boundary migration that results in the diminishing of some small (sub-) grains or crystal fragments, and the increase of grain boundary misorientation, as indicated by the white arrows, where two triangular-shaped (sub-) grains with well defined grain boundary fringes on their all three boundaries was diminishing by the migration of their all three grain boundaries 0.1µm a b Fig. 5 Typical features of (sub) grain boundary activity observed in samples during ECAP observed.

Data were collected at a sufficient number of points within each cycle so as to obtain the detailed response of orientation-specific grain groups.
Cycle numbers for unloading analysis also are shown.
-400 -300 -200 -100 0 100 200 300 400 0 0.5 1 1.5 2 2.5 Cycle number hkl microstrain 111 200 220 311 Fig. 3.
The evolution of orientation-specific residual elastic strains as a function of the number of cycles.
Evolution of residual strains (hk.l), and the difference strain 100 001ε ε− , with the number of unload (see text).

The situation can become fast impossible to manage, especially for some rolling processes, which involve high number of passes 2) Both families of grains generated at the end of each pass can be merged into just one family, with a weighted average grain size according to the respective fraction of recrystallized and strain hardened grains.
This methodology cannot be applied for superalloys: generation of new grains involves significantly higher strain values [5]. 3) Between these two extreme approaches, specific treatments of microstructures obtained after each pass can be undertaken, in order to reduce the number of grain families we have to manage, without coming up to just one family as specified above.
Related to the processing of strain hardened grains and considering the same example as above, Figure 3 shows the comparison between the calculated and measured recrystallized fraction Xtot as a function of number passes.
For instance, it is possible to calculate the number of recrystallization sequences during the process.
Microstructure appears fully recrystallized with a homogenous grain size even if computation leads to a decimal number for the recrystallization fraction.