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However, the exact variations of the hardness with increasing number of passes were not given.
There aren’t any apparent grain boundaries but a large number of black Mg2Si particulates in the annealed Al alloy.
After one ECAE pass, the grains are elongated and broken, and the grain size is remarkably refined.
Previous studies reveal that there are a large number of equiaxed ultra-fine dislocation cells in the stripped grains, and the formation of dislocation cells or subgrains is the main mechanism of sub-micron microstructure development [16-18].
Then the hardness decreases successively with additional numbers of passes.

The sediment transport parameters such as fall velocity, Shield parameter, D50, D90, sediment density, Reynolds number, Grain-related Chezy coefficient, bed form factor, and shear stress were determined.
The mean grain diameter follows (0.2≤Dm≤5) millimeters.
The values of the Reynolds number exceeded x×105, where x is a positive integer.
Particle size distribution test/Grain size analysis iii.
The values of the Reynolds number exceeded x×105, where x is a positive integer.

In order to observe easily, two flank side of box is made of organic glass. ② is the sand grains.
Table 1: Physical Parameters of Model Experiment Materials and Experiment Design Order Number Grain Diameter （mm） Particle Shape Apparent Density(kg/m3) Internal Friction Angleφ(°) Filling Height（cm） Compaction 1 5～10 Crushed Rock 2733 39.94 50 0.80 2 10～20 Crushed Rock 2731 43.16 50 0.80 3 10～30 Crushed Rock 2731 44.19 50 0.80 4 20～40 Crushed Rock 2727 45.94 50 0.80 5 40～60 Crushed Rock 2729 46.63 50 0.80 6 10～20 Pebble 2627 39.96 50 0.80 7 20～40 Pebble 2633 42.38 50 0.80 8 40～60 Pebble 2631 43.63 50 0.80 Figure 8.
The Volume of Granular at Limit Loose State In order to find out the effected factors of the secondary loose coefficient, the relationships of grain diameter of crushed rock, grain figure of gravel with it were analyzed.
As it shows, the secondary loose coefficient increased with grain diameter of crushed rock.
(3) The secondary loose coefficient increases with grain diameter of crushed rock and pebble, and the secondary loose coefficient of crushed rock is always higher than that of pebble at same grain diameter.

Average grain size of this structure was defined as ~280 µm.
Apart from that, all the grains have grey contrast and grain boundaries are not clear and evident any more.
The formation of stable lamellar flow pattern was more apparent as number of TE passes increased.
Distribution of the average grain sizes was almost homogeneous.
The Office of Naval Research Global (ONRG) is greatly acknowledged for his partial support for the participation at the conference through the grant number N00014-08-1-1011.

It can be found that the average grain size declined gradually, the minimum grain size of 20 nm appeared at time of 15 min, then it increased with the processing time increasing.
It indicates that there are a large number of nano-scale twins (Fig. 4(e)), which are confirmed by the corresponding SAED pattern, plate strips (Fig. 4(f)), and equiaxed sub-grains(Fig. 4(g)) derived from dislocation cells.
The average grain size of surface is around 20 nm.
With further deformation, dislocation cells became sub-grains.
Finally, the refined plate strips, twins and sub-grains transform nanostructured grains with random orientation.

This glassy phase also wetted the zirconia grains and prevented the grain growth and the formation of facetted grains.
An average grain size was obtained by multiplying 1.78 to average intercept lengths over 1000 grains.
This glassy phase wetted the zirconia grains and formed rounded grains.
When a crack propagates it follows either the grain boundaries or around grains.
Acknowledgements This work has been supported by DPT (the State Planning Organization of Turkey) under project numbers 2003K120470 and 2001K120590.

In addition, as grain refinement, increased grain boundary carbides are evenly distributed in the grain boundary, thus greatly reducing the number of grain boundary carbides.
Austenite grain boundaries as in a number of nuclei formed, the austenite grain becomes a number of pearlite grain groups, reaching the purpose of grain refinement.
Austenite recrystallization, the nuclei in the cementite ferrite interface formation, the higher the dispersion of pearlite, the more austenite recrystallization nucleation, the more the number of pearlite grain groups, after the change, austenite grain increased, grain refinement[5].
Grain size have a great impact to the mechanical properties of the alloys, because the grain boundary disorder on the atomic arrangement, a number of impurity defects and grain boundaries on both sides of the bit to different, hindering dislocation from one grain to another the movement of grain, the finer the grain, the greater the grain boundary per unit volume, the greater the resistance to dislocation, the higher the strength of the material.
In this study, high-manganese steel of the blast-hardened have been carried out by micro-observation and X-ray diffraction analysis, It can be seen from figure 5, the two samples have shown a significant slip lines, and the samples with modified SiC nano-powders appear more slip-line the number of grains, even the emergence of a grain slip-line in different directions, and the hardened layer deeper.

The equiaxed grain shape is expected in route C since the grain restores equiaxed shape at every other passes.
The grain structure in route C also appeared to be rather close to a high angle grain boundary network.
In route Bc, the grains are small in size and the yield stress is high because of small grain size.
The uniform elongation regime is comparatively large considering small grain size and this was because the grain structure is composed of high angle grain boundaries.
Acknowledgement Authors are grateful to the Korea Science and Engineering Foundation for their financial support of this research through the grant number R01-2005-000-11247-0.

Macroscopic work hardening description needs to account the hardening process at the grains scale.
This model allows each grain to deform differently, depending on the strength of the interaction between the grain and its surroundings.
Analyzing the τ-γ behavior for individual orientations, Cases I and II show interesting differences: − The number of deformation systems activated in case I is lower than in case II.
− Performing statistics on the ensemble of grains, the greater deformation systems activity reported for the case II is also evidenced by the evolution of the mean value of this activity in grains.
Fig. 2: Evolution of the average number of active deformation systems with deformation.

While most grains are of the order of only 3 µm, larger grains of 10 to 12 µm in size are also present.
The arrow in Fig. 3a points to a high angle grain boundary which is incomplete and has "degenerated" into low angle grain boundary tails.
The grains are almost equiaxed and the variation in grain size is significantly reduced.
As the number of ECAP passes increases from 2 to 4 (Fig. 5c), the intensity of this texture component is clearly becoming more dominant.
As the number of ECAP passes is increased from 2 to 4, both yield stress and tensile strength are enhanced.