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The number of the acid centers of the carrier fixed loading became larger and the combination turned more firm.
Analysis of specific surface area, grain size and sulphur content .
The average grain size of the catalyst SZ samples was 148 nm and the average grain size of the catalyst SZ-C samples was 99 nm.
The smaller the grain size, the larger the specific surface area of the catalyst with the same mass, the more the number of the acid centers, the higher the catalytic activity.
While the grain size of the catalyst SZ-C was small and even.

The HPT strain degree was varied by the number of rotations or turns (n) from 1 to 7.
The transformation yield stress for martensitic transformation (sm) of the nanocrystalline alloy with a grain size of 20 nm is about 450 MPa (Fig. 1b), which is three times higher than sm in the initial coarse-grained state (sm » 160 MPa).
It is clearly obvious that sm value increases as grain size decreases.
Microstructure of the Ti49.8Ni50.2 alloy after ECAP 4500C n= 8 (a) and stress-strain curves (b) in the initial state and after ECAP with the same number of passes After ECAP processing ductility decreases, however, remains sufficiently high – about 25%.
The maximum recovery stress σrmax increases with the increase of the number of ECAP passes, achieving 1080 MPa after 8 passes and 1120 MPa after 12 passes, which exceeds the level of the initial condition (480 MPa) by more than 2 times [4].

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).

Grain refinement and precipitation hardening are the main reasons for high strength, and toughness improvement can be attributed to grain refinement and particular microstructural characteristics of AF.
Large number of nanometer particles distribute in X80 pipeline steel, which is given in Fig.4.
Grain refinement can be achieved through repeated recryatallizaiton of austenite during hot rolling.
Sub grain and high density dislocations are characterization of acicular ferrite.
Large number of nanometer particles exist in experimental steel.

For example, one can investigate the grain size due to deformation in a metal.
The electronic circuitry measures the number of events vs. the delay time between the start and stop signals 2-2.
More detailed measurements of e+ annihilation on fine-grained ZnAl alloys as a function of the mean grain size were also reported by [12,13].
For large grain sizes, the mean lifetime t varies linearly with the inverse grain size l-1, in agreement with most of the available experimental data [13].
The comparison of observed‘d’ values with standard ‘d’ values (PDF number 04-0787) indicates that the 5251Al samples are polycrystalline and have face centered cubic structure.

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.

However, if the number of stacking layers and/or the reduction per pass increases some advantages will be expected [3].
Ia increases with the number of passes, which means that the severity of the process also does.
Evolution of the average intensity Ia with the number of passes in the ARBed samples.
Equiaxed cells/(sub)grains with diameter smaller than 1 µm are seen.
However, the cell/(sub)grain size of the three deformed samples is very similar.

As shown in a number of papers, this results in acceleration of diffusion processes, and, consequently, the processes of structure transformation start at lower temperatures than in traditional coarse-grained materials.
Its initial grain size was 50 µm.
Subgrains are observed within coarse grains.
Note that the coarse grain size achieves 2 µm, and the volume fraction of grains, 1-2 µm in size, is 40%.
As a result, the activation energy of grains is decreased essentially and the additional stage of rapid grain growth appears on the grain size-temperature curve (Fig. 2).

Mean grain diameters in samples cast in permanent mold (φ 80×50mm) were determined by line analysis.
Morphologies of inclusions, grain structures and Fe-rich phases are shown in Fig. 1 to Fig. 3.
After high-efficient melt-treatment, inclusions in the samples exist uniformly in the tiny flake/particle form, and their number is very few (Fig. 1 [c]), and grain appears in the fine equiaxed form (Fig. 2 [c]), and Fe-rich phases transform into tiny, sphere/short stick form (Fig. 3 [c]), EDAX analysis has shown that the phases are turned into complex (AlFeSiRE) compounds.
For Al piece prepared by high-efficient melt-treatment, the inclusions content and the number of micro-porosities are all reduced obviously, and the Fe-rich phases are changed into a favorable form, which decreases the number of microcrack sources resulting in the fracture of the material remarkably, thus making the mixed fracture fashion be transformed into the congregation of transgranular micro-hole.
Since the number of defects is very few, their mean distance is larger, thus increasing the resistant force of crack expansion.

Furthermore, when the strain reaches a value of 4, a significant number of ultrafine grains have formed with the fraction of the HAGBs increasing continuously with strain.
A larger number of ultrafine grains were noticed in the region of higher strain, indicating that these grains are formed by a process of fragmentation/subdivision of initial grains.
It may be noted from Fig. 3(a) that even at a strain of 0.5, ultrafine grains, though few in number, have formed at the original grain boundaries and their volume fraction increases with increasing strain.
(I). purely elongated grains; (II). elongated grains with newly generated grains; and (III). newly generated grains.
Considering the large number of defects in ultrafine grained materials, it is appropriate to consider the grain boundary diffusion as the controlling mechanism of ferrite grain size, we obtain the relationship: ( ) 2/1 tDTH gb=α (3) The constant strain rate (ε& ) deformation at high temperatures can be divided into an amount of instantaneous plastic deformation (ε) and static annealing for a given period ( tt / ; εε=& ).