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Due to changing the deformation axis, the fraction of severely deformed areas increases with increasing number of passes and very high cumulative strain becomes possible [16,17].
The number of deformation bands was rose owing to increasing a cumulative strain from 3 to 6.
Grain growth led to increasing the grain size in a fine grained area from 5.3 to 8.2 µm in the samples pre-deformed at 400 °C.
The mean grain size in a fine-grained area increased from 10.2 µm to 10.9 µm and fraction of fine recrystallized grains decreased from 54% to 32%.
Bimodal grain structure with 40 % of coarse grains and 60 % of fine grains was formed after 4 cycles.

Particles from 5 to 1 μm in size were found both within grain bodies and along grain boundaries.
Mg2Ca particles up to 1 μm in size are also found in grain bodies, while their size at grain boundaries constituted 4 μm.
Some grains contained high-density dislocations (Fig. 2, c), while large grains were mainly free from dislocations.
Grains have distinct boundaries typical of recrystallized grains (Figure 4b, c, d).
A non-uniform contrast in HPT-processed samples subjected to further annealing at 150 оC implies the presence of a large number of dislocations pointing to still high internal stress in the structure (Figure 5а).

For this aim, a number of ways such as alloying, heat treatment, transformation of silicon particles into spherical form with the help of elements such as sodium and strontium, and grain size reduction with grain refiners have been tried [2-4].
In addition, the E% of the homogenized sample shows a continuous increase with increasing pass number.
As seen in this figure, microhardness and hardness decrease with increasing pass number.
Principles of equal-channel angular pressing as a processing tool for grain refinement. 
Ultra-fine grained bulk aluminum produced by accumulative roll-bonding (ARB) process. 

By increasing the embryo density in austenite through deformation, the number of martensite grains increases.
Therefore, it is not obvious that the grain size of BM grains can be represented by the width of grains.
BM grains have peculiar anisotropic geometry: two coarse grains collide to form one BM grain.
(a) Definition of the grain width of LM grains and BM grains.
When a microstructure consists of only LM grains, the index of the grain size distribution is the width of LM grains.

Introduction Ultrafine grained (UFG) metallic materials having grain size smaller than 1 µm can be realized by various means including severe plastic deformation (SPD) [1].
The mean grain sizes were measured by mean interception method.
In the previously studied ARB materials, the strength became higher with increasing the number of ARB cycles, and the elongation dropped down below 10 % by 1 ARB cycle.
The mean grain thickness is 210 nm.
The mean grain thickness is 170 nm.

A large number of pores, high water consumption, and weak supersaturation of the solution characterize the concrete made of such cement and lead to decrease in the strength.
The sand fineness modulus Mfn = 1.29: no grains larger than 5 mm; the share of grains with a diameter of less than 0.16 mm is 8.7%; the content of pulverized and clay particles is 0.84% [7].
Research Results The cement grains have sizes from 1 to 100 μm [8, 9].
Ivanov-Gorodov believes [10] that uniform and rapid hardening of cement is achieved with the following grain compositions: grains smaller than 5 μm compound no more than 20%, grains of 5-20 μm in size are about 40-45%, grains 20-40 microns in size - 20-25%, and grains larger than 40 microns - 15-20%.
Concrete obtained using cement mechanically activated in the activator Pulverizette-6, has a more loose structure with a large number of different forming elements.

Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman.
A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain.
The characteristic length is inversely proportional to a so called brittleness number B [3]: . (5) In Eq. 5 L is a significant specimen dimension.
Fig. 1: Schematic drawing of wedge splitting test according to Tschegg [4,5]; numbers and symbols are explained in text.
The Matrix contains the majority of the porosity, strength of the matrix and especially the grain/matrix interface is expected to be considerably lower than that of the grain.

The microstructure evolution of AA 3103 with growing number of ECAP passes is presented in Fig. 3.
During annealing similar trends were observed irrespective of the number of ECAP passes.
Apparently, the precipitation kinetics are sped up in samples after higher number of ECAP passes (N>4), most likely due to the high fraction of high angle grain boundaries and therefore accelerated diffusion processes.
ECAP deformation up to eight passes in route Bc led to the formation of an ultra-fine grained structure with a mean grain size of about 500 nm.
ECAP processed AA 3103 showed increased stability against discontinuous recrystallization with growing number of passes due to accelerated dispersoid formation at higher number of passes.

The grain sizes were calculated with Scherrer formula.
In our previous research paper[1], the grain sizes are calculated with Scherrer formula and 240 nm of averages grain size of Zn milled for 3 h is obtained.
A broad grain size distribution (5-500nm) with a large number of 5-10 nm grains is observed.
Fig.2 shows the normalized yield strength and % elongation data for ultrafine grain materials (grain size of 100 -500nm)[6].
Fig.4 represents the typical ductile fracture which includes a number of dimples, the central interior region of the surface which has an irregular and fibrous appearance.

The solution with the greatest number of votes is deemed the most likely.
Comparisons are then made of the number of observed spots in the RDP with those predicted in a simulation of the pattern using the mean orientation.
Numerous studies have been made using the DFC procedure to form OIM images on a large number of materials most of which were single-phase materials.
The number of spots observed was also less than what was seen in a selected are diffraction pattern recorded from the same area.
Hence grain map 6b is a better representation of the grain contiguity than that shown in figure 6a.