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The LM micrographs of ARB samples in Fig. 2a,b show gradual grain flattening with increasing number of ARB cycles.
The size of the lamellae does not change significantly with the increasing number of cycles in AA8006 specimens.
Moreover, in contrast to AA8006 alloy, in AA5754 alloy lND shows a decreasing tendency with the number of ARB cycles.
Grain subdivision by low-angle boundaries (LAGB) and a progressive conversion of LAGB into high-angle grain boundaries occurs with increasing number of cycles in all alloys.
On the contrary, the alloy AA5754 exhibits a steady increase in hardness with increasing number of ARB cycles.

In this study, appearances of grain interior strain localizations are related to the number of grain interior high angle boundaries: as estimated by EBSD.
The dislocation density increases linearly with increase in number of grain interior strain localizations for both g and q fibres (Fig. 3).
Fig. 2: Number of grain interior high angle boundaries as a function of temperature and strain rate.
Fig. 3: Dislocation density as a function of number of grain interior high angle boundaries.
Fig. 4: X-ray resolution function as a function of number of grain interior high angle boundaries.

In a number of areas of engineering practice, alloying may be unacceptable, for example in medical materials for reasons of biological compatibility, or undesirable, as in nuclear materials due to deterioration in functional properties and the need for long-term tests when putting into operation of new material.
In recent decades, great progress has been made in obtaining materials with ultrafine grain.
In an effort to use grain refinement to increase the yield strength and strength of metal materials, various technologies for producing fine grains of polycrystalline aggregate were developed (see, for example, reviews [1-5]).
This made it possible to obtain metal materials with virtually any grain size up to 100 nm or less.
Conclusion The SLM method makes it possible to form an ultrafine-grained structure.

After 4th pass, the avarage grain size decreased from initial approximate size 7 µm to 200 nm, whereby the average grain size was changeless after subsequent deformations.
Introduction Present scientific research is intensive oriented on ultra-fine grained structures formation (UFG with grain diameter 1µm-200 nm), and nanoscale structures (NSG with grain diameter ≤ 200nm) in polyedric metallic materials, attained through the use of SPD.
Initial Cu structure is coarse grained, with average grain size 7 µm and low yield strength and tensile strength, but with sharply defined reduction of area (82%).
The initial material grain shape is polygonal and uniform.
With the growing number of ECAP passes, the dimple size decreases and the quantity of dimples increase.

Different scales of gray in the image indicate different grain orientations, rather than the phase difference at atomic numbers, as in the backscattered electron image.
In these two cases, the sample with higher current is accompanied with more incident electrons, which leads to more significant differences in the number of backscattered electrons among grains with different orientations, and therefore more obvious contrast differences.
When the accelerating voltage is 1kV, the differences in the number of backscattered electrons are very small among grains with different orientations because of the small number of generated backscattered electrons; hence, many of the grains cannot be distinguished (Fig. 7a).When the accelerating voltage is 2kV, the distinction among the number of backscattered electrons for grains with different orientations becomes quite obvious, leading to an obvious channel effect contrast (Fig. 7b).When the accelerating voltage is increased to 5kV, the differences among grains with different orientations decreases (Fig. 7c).When the accelerating voltage is increased to 10kV, the channel effect contrast continues to attenuate (Fig. 7d).When the accelerating voltage is increased to 15kV and 20kV, the channel effect contrast actually strengthens compared with that of 10 kV (Figs. 7e and 7f).
However, there are still a small number of grains that can only be clearly distinguished by EBSD, but not by the channel effect contrast images (such as grains 1–9).
The interfacial angles between the unidentified grains are very small, such as 8° between grains 1 and 2, 4° between grains 3 and 4, 7° degrees between grains 5 and 6, and 2° degrees between grains 7 and 8.

(3) where the parameters are: ψ=exp(η/2), ψ = exp(-η/2), ϕ≈bV/Deff, with C, the macroscopic atomic concentration of Mn; N, number of atoms per m3 (1/b 3); E0, interaction energy in the grain boundary; k, Boltzmann factor; η= kTE /0 ; b, interatomic distance in the lattice; V, velocity of the grain boundary and Deff the effective diffusion rate.
The analysed grains during the experiments were those with "random" grain boundaries.
The "tilt" grain boundaries or the grain boundaries, which showed impingement, were excluded from the present study.
Because the rapid recrystallization grains were too fast to be followed and because grain impingement occurred in the very early stage of the annealing experiments only the slower recrystallization grains were tracked.
Grain boundary mobilities and activation energy The grain boundary mobility (M) of each HAGB of the recrystallizing grains was obtained by dividing the grain boundary migration rate (V) by the current driving force (P) for temperatures of 200-300°C.

Some use of this method based on grain boundary movement velocity equation, as Ceppi and Nasello tracked each grain boundary's movement based on the linear assumption of grain growth, "the movement speed of normal line of grain boundary is proportional to the curvature of grain boundary".
Grain sides number distribution got from this simulation became wider with time increase; this doesn't match to most other researches.
Application in simulation of grain growth during superplastic deformation We analyzed grain growth mechanism, thought that grain growth is driven by grain boundary energy and deformation strain energy came from superplastic deformation grain boundary sliding being prohibited.
The energy can be expressed as equation(2): ( )11 1 1 2 i j i n m n s s s i j i J E Hδ = = = = − +∑∑ ∑ (2) where the first item is the general crystal boundary energy, the secondly is the general shaping energy, siH is the shaping energy of Si crystal lattice, E is the system energy, n is crystal lattice numbers in system, m is the number of vicinity nodes.
Computer Simulation of Grain Growth.

Fine Grained Mortar (FGM) offers a new innovative technology binder system to strengthen or repair concrete structures.
The innovative technique is achieved by using a small maximum grain size of 1 mm for the mortars.
Fine Grained Mortar Fine grained mortar is a special binder system which is achieved by using a small maximum grain size of 0.6 mm to 1 mm.
Ongoing Studies Studies of the used of FA as a cement replacement in FGM have been reported by a number of researches.
Then were ground by grinder until 95% of the particles could pass trough sieve number 325 (45µm) complying the requirement of ASTM C618 [33].

However, it was difficult to observe these submicron grains and submicron grain boundaries under optical microscope.
These elongated grains after the first ECAE treatment were replaced by essentially equiaxed array of submicron grains with an average grain size of ~500 nm after the fourth ECAE treatment, and further were refined to an equiaxed array of fine submicron grains with an average grain size of ~300 nm after the eighth passes ECAE.
And with the increase in the number of ECAE processes, it can be seen that the contact angle decreasing along with surface energy increasing.
Along with the increasing number of pressings, both accumulative strain and misorientation angle consistently increases while grains size and aspect ratio decrease.
In this research, the submicron grains with an average grain size of ~500 nm after the fourth ECAE were refined to an average grain size of ~300 nm after the eighth ECAE treatment.

Recently, CEC was successfully applied to few number of materials to produce ultra-fine grain structures such as AZ31 alloy[20], Mg–Zn–Y–Nd alloy [21] and AM60B magnesium alloy[19].
It is apparent from the observations in the present microstructures that the grain structure has been enhanced with CEC deformation due to reducing the grain size.
Small new grains are found in the CEC deformed structure after 2 pass, see Fig. 2(c).
Fig. 4 shows the hardness variation with the extruded Al-1Cu alloy with the number of CEC passes.
It is clear that the hardness is noticeably affected by the number of deformation passes.