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Subsequently, there have been numerous reports of superplastic flow in a wide range of Al alloys processed by ECAP including a number of commercial Al alloys.
This trend was also reported for an Al-Mg-Li-Zr alloy [22] and it is reasonable to conclude this is a direct consequence of the increase in the fraction of highangle boundaries with increasing strain and therefore with increasing numbers of passes in ECAP [23,24].
It was observed that the extruded material already contained a fine microstructure with grains of the order of a few micrometers surrounded by even smaller grains at the boundaries but nevertheless the grain structure was significantly refined after processing by ECAP.
Despite the extensive measurements of grain boundary sliding in materials processed without ECAP, there has been only a limited evaluation of the role of grain boundary sliding in materials produced by ECAP and having ultrafine grain sizes.
It should be noted that the phases with white color indicate the Zn grains and those with black color indicate the Al grains.

Kinetics of Phosphorus Segregation in the Grain Boundaries of VVER-1000 Pressure Vessel Steels Boris S.
Parameters of the steel grains Average grain diameter optical metallography (100 ± 25) µm Average subgrain diameter optical metallography (50 ± 15) µm The average number of subgrains in the grain optical metallography 8 ± 3 Average subgrain diameter SEM (2 ± 1) µm The average number of subgrains in the grain SEM (120 ± 30)·103 Average dislocation density 1010 cm–2 Phase Parameters of the phase precipitates TEM SEM V(C,N) The number of the particles in the grain bulk 2·109 2,1·109 Average linear dimension, nm 20 20 Average particle volume, m3 940·10–27 940·10–27 Volume density in the grain bulks, particles/m3 4.0·1021 4.2·1021 (Cr,Mo)23C6 The number of carbide particles in the grain bulk 3.5·107 2.3·107 Average linear dimension, nm 100 110 Average particle volume, m3 5.2·10–22 7.0·10–22 Particle density on the grain surface, particles/m2 4.5·1012 3.5·1012 Volume density, particles/m3 0.7·1020 0.45·1020 Steel samples, having 3.1 mm diameter and ~ 15-20 mm length, with a circular notch
Conclusions The method of quantitative AES analysis of grain boundaries in pressure vessel steel is developed.
McLean, Grain Boundaries in Metals, Clarendon Press, Oxford, 1957
Gurovich, Effect of subgrain structure on the kinetics of phosphorus segregation in grain boundaries, Mat.

Severe plastic deformation techniques like equal channel angular pressing or accumulative roll bonding are used by number of researchers.
It is clear that the equiaxed α grains are surrounded by high angle grain boundaries (HAGBs).
When the smallest dimension of the grains becomes comparable to the size of grain boundary serration, DRX grains surrounded by high-angle boundaries is formed by the impingement of serrated initial grain boundaries in the geometrical DRX.
It is seen that θ particles exist on the grain boundaries of equiaxed α grains.
Meanwhile the final α grain size decreased.

The transition is strongly grain size dependent, with the time to the transition decreasing with grain size.
For sliding frictional contact, the time to the transition is dependent on a number of extrinsic variables (load and speed) and intrinsic material variables, principally grain size.
The grain size is reasonably fine, however, there is a significant distribution in grain size.
Firstly, there has been differential wear between grains.
This means that, for a given time of operation, there will be greater dislocation activity in larger grain materials, leading to greater rotation of the grains and greater stress concentrations on grain boundaries [1,2,6].

The size of the primary silicon grains decreases and the grain number density rises with the increase of the magnetic strength maintaining the magnetization force unchangeable.
Thirdly, the solidification structures of longitudinal section of the solidified samples were examined at first, then tested the mean diameter (d0) and the particles number density (NV) of the segregated primary silicon grains by the quantitative method in morphology.
Furthermore, with the increment of the magnetic flux density, the difference of the grain size (to define ,and are the maximum and minimum diameter of the grains, respectively) decreases, but increases the number particle density.
ML+2MS is called as strength field magnetic quantum number. , called as Bohr magneton.
(2) Keeping the magnetization force same, the sizes of the primary silicon grains in segregated layer decrease with the increment of the magnetic flux density, but the particle number density increases

China Keywords: Grain boundary engineering, Equal-channel angular pressing, Grain boundary character distribution, OFHC copper.
A great number of studies showed that special grain boundaries, described in low-Σ coincidence site lattice (CSL) boundaries (usually Σ ≤ 29), especially Σ3n (n=1, 2, 3) boundaries possess special chemical and mechanical properties [1-3].
The average grain size of the as-received materials was about 10 μm.
Moreover, the average grain size decreased with increasing of the strain level.
Owen, Mechanisms of grain boundary engineering, Acta Mater. 54 (2006) 1777-1783

Stress Induced Grain Boundary Motion in Al bicrystals Dmitri A.
Usually, starting from one location at the initial boundary these grains develop into groups of sub-grains separated from each other and the original consumed grain of the bicrystal by low angle boundaries.
The boundaries between sub-grains and the growing grain remain stable and with progressing migration of the original grain boundary the sub-grains become wider (Fig. 4).
Apparently, the formation of new grains observed in the current experiment is facilitated by the nucleation of a sufficient number of lattice dislocations by the grain boundary during its stress driven migration coupled to shear deformation.
Then, these dislocations build walls and finally turn into sessile boundaries between the new grain and the growing grain of the original bicrystal and the moving low angle boundary that separates the new grain from the consumed grain of the original bicrystal (Fig. 4).

Smaller sub-grains could be developed by further grain-coarsening (Fig. 1) in these grains by modifying the simulation.
The effects of the following parameters were investigated: ferrite/cementite interface free energies, temperature, carbon concentration, pearlite grain size number, pearlite interlamellar spacing.
Ever fewer nuclei of type 3 develop if the interface free energy decreases and at the end the number of type 3 nuclei will be lower than the number of type 1 nuclei.
An approximately linear curve is kept for the nucleation rate as a function of grain size number (Fig. 8).
Model of grain growth.

It has been shown that doping enhances the formation of grain blocks with a radial gradient in the direction of grain growth.
Separation into fractions was performed by sieves with numbers: 0.020, 0.056, 0.100, 0.160, 0.400 and 0.630 mm.
This alloy is also characterized by the formation of grain blocks with a radial gradient in the direction of grain growth.
The shape of the grains varies in fractions.
Fig. 6 Size distribution of grains with corresponding grain anisotropy for a fraction of 0.160-0.400 mm of Fe82,0Nd12,0B6,0 alloy Table 1 Average values of the maximum grain length and anisotropy Fraction, mm Parameter №1 №2 №3 №4 0,0-0,020 The maximum grain length, microns 4,079 5,013 8,868 8,556 The average grain anisotropy, counts 1,989 2,243 1,626 2,236 0,020-0,056 The maximum grain length, microns 6,794 11,321 12,934 9,311 The average grain anisotropy, counts 2,021 2,334 2,032 2,113 0,056-0,100 The maximum grain length, microns 10,962 28,536 12,702 7,689 The average grain anisotropy, counts 2,063 2,775 1,519 1,958 0,100-0,160 The maximum grain length, microns 29,632 40,802 60,577 9,710 The average grain anisotropy, counts 2,263 2,354 2,142 2,104 0,160-0,400 The maximum grain length, microns 19,47 43,544 44,621 6,167 The average grain anisotropy, counts 2,034 2,130 2,002 1,758 0,400-0,630 The maximum grain length, microns 41,867 37,516 75,778 8,367 The average grain anisotropy,

The values of KIC in AZ31 magnesium alloys were dependent on the grain size.
Introduction A number of magnesium alloys have been shown to exhibit excellent mechanical properties, such as high specific strength at room temperature and superplasticity at elevated temperatures [1-4].
From Fig. 1, the initial grain size was about 1.0 µm.
Effect of grain size refinement Many researchers have been pointed out that the values of fracture toughness are dependent on the grain size in a lot of kind of materials such as Ti-, Fe- and Al-alloys [23-25].
The values of KIC in AZ31 magnesium alloys were increased with grain refinement.