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Ferrite grain size of electropulsed samples was refined compared to similarly annealed samples.
To assess the difference between electropulsed and conventionally heat-treated annealed microstructures, a number of samples were furnace treated at a range of temperatures below the eutectoid temperature (728°C) (Fig. 6-8).
Comparing with the ferrite grain size of the unelectropulsed samples furnace-treated at 650 and 700 ºC (Fig.10), it was found that: i) a higher percentage of electropulsed grains (85%) than furnace treated grains (39% and 66% respectively) were smaller than 0.5μm2; ii) a higher percentage of electropulsed grains (83%) than furnace treated grains (33% and 48% respectively) had major axis length less than or equal to 1μm; iii) a higher percentage of electropulsed grains (84%) than furnace treated grains (47% and 57% respectively) had aspect ratio (major axis/minor axis length) less than or equal to 2.
These findings show that electropulsing produced a larger number of smaller equiaxial ferrite grains than traditional annealing over a similar time/temperature regime. 6 7 8 Figure 6-8.
Similar grain growth retardation behaviour has been reported in the literature in different materials [8,9].

There the basic mechanisms on recrystallization in aluminum have been already understood quiet well [1] and have been sophisticated by a considerable number of studies for many years [2-4].
Grain growth and grain boundary movement.
Figure 3 shows the grain growth behaviors of a grain nucleated on a grain boundary (X1, Y1 in Fig.2) and a grain nucleated in a deformed band (X2, Y2 in Fig.2).
As shown in the Fig.3, the grain growth of the grain in the deformed band is larger than that on the grain boundary in each specimen.
The grain boundary of Y2-grain neighboring the deformed matrix moved more rapidly than that of Y1-grain.

As far as the production method of fine-grained materials of small dimensions has been fully mastered, the producing of fine-grained materials of considerable dimension is still a matter of challenge for engineers.
They are able to transfer very large plastic deformation, retaining the same positions while cutting through a number of grains.
Thus, there are no reasons for grain growth.
The very large plastic strain of these heat treatable alloys results in fine particles shearing by a number of dislocations, leading to their mechanical supersaturation as well as to channeling of the structure by intersecting shear bands causing its refinement and achievement of a chess-board like form.
The subgrain/grain growth is then retarded due to disperse particle development.

High-angle grain boundaries increase in number with increasing the amount of cold-work.
Results and Discussion Grain size, hardness and resistivity.
Up to 7 cycles of ARB the average grain size continues to decrease, and both the hardness and resistivity increases with the number of cycles, N.
Contributions of grain boundaries to the Fig. 1.
This work was supported by Grant-in-Aid for Scientific Research by Ministry of Education, Culture, Sports, Science and Technology, Japan, under project numbers 19025007, 19360288 and 21360311.

For the classification of structural changes at cyclic deformation of high-purity aluminium the dependence of microhardness on the number of loading cycles was chosen (Fig. 1).
This process is accompanied by the abrupt microhardness increase with the increasing number of loading cycles.
The dependence of microhardness on the number of loading cycles The II-nd Stage is characterized by the abrupt decrease of microhardness increase speed (Fig.1).
The grain-boundary migration is a highly effective accommodative process of contiguous deformable grains.
This fact proves that the grain boundary hardness is smaller than the hardness of the grain volume.

Introduction Grain plays an important role in Chinese food safety and national economy.
Chinese grain situation will be still in tight balance, and there must be an increase above 4000 million kg annually in order to meet the demand of grain in 2020 [1].
This may influence the situation of grain production and supply.
Table 2：The corn production efficiency distribution of the farm households (in the year of 2011) CRSTE VRSTE SCALE Efficiency score grouping Numbers of Households Proportion % Numbers of Households Proportion % Numbers of Households Proportion % 1 4 2.34 11 6.4 4 2.34 0.9~1 3 1.75 8 4.7 95 55.56 0.8~0.9 10 5.85 11 6.4 58 33.9 0.7~0.8 12 7.02 19 11 5 2.92 0.6~0.7 33 19.3 39 23 4 2.34 0.5~0.6 42 24.57 41 24 3 1.75 0.4~0.5 48 28.0 27 16 1 0.58 0.3~0.4 12 7.02 12 7 0 0 <0.3 7 4.09 3 1.8 1 0.58 >Average values 80 46.78 70 41 109 63.74 The impact of industrialization and urbanization has brought an increasing number of young persons leaving from agriculture, which led to the aging showing a negative effect.

It was found that the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, the coarse β-Mg17Al12 phase distributed along the grain boundaries transformed into granular, and the granular or acicular Al3Nd phase precipitated in matrix.
When the chemical composition and corrosion medium have relatively fixed, the grain size of α-Mg phase, the number of β-Mg17Al12 phase and its distribution have greatly impact on the corrosion of magnesium alloys, particularly AZ91 alloy [6,7].
So, the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency.
Hence, the general corrosion is composed of numbers of micro-couple corrosion.
（a） （b） Fig.3 Relationship between corrosion rate-time, weight loss rate-time of AZ91/AZ91-0.4%Nd alloy immersed in 3.5 wt.% NaCl solution(a)corrosion rate;(b)weight loss rate Conclusions The number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, the coarse β-Mg17Al12 phase distributed along the grain boundaries transformed into granular, and the granular or acicular Al3Nd phase precipitated in matrix.

Fatigue-Crack-Growth Behavior of Ultrafine-Grained Al-Mg-Sc alloy Produced by ECAP E.
After extrusion and annealing, the alloy was composed of a non-uniform partially recrystallized microstructure with a bimodal distribution of the grain size, namely, coarse elongated grains lying parallel to the extrusion axis, and fine equiaxed grains in their mantle regions (Fig. 1(a)).
Besides, some remnant parts of original grains were present in this structure.
Data for coarse-grained Al-6%Mg-0.3%Sc alloy are plotted for comparison.
The size of facets is gradually increased with increasing ∆K, so that every facet "covers" a number of UFG grains.

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.

The ECAP was conducted at a temperature 643 K in accordance with processing routine BC (sample rotating angle between passes of 90 o ) with the number of passes N=12.
This earlier study revealed a high dislocation density (ρ ∼5⋅10 9cm-2) and a number of intermetallic particles (Al3Sc and Al3Zr) with 30-60 nm sizes in the grain volume.
The ECAP processing gives a significant decrease in the average grain size of the alloy to an ultra-fine grained state (d ≈ 1 µm).
The grain boundaries in the 1421 alloy after ECAP through a large number of passes demonstrate a spread contrast that is characteristic of an equilibrium state.
The value of Ug in the initial alloy is close to that for grain boundary self-diffusion of Al [15] or Mg diffusion along grain boundaries of an ultra-fine grained Al-Mg alloy [16].