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Second, nanosized grains induce the formation of special grain boundary amorphous layer and complex wavy interfaces [6-7].
It is visible in Fig. 1b that a large number of spherical precipitates are formed.
Fig. 1f shows the grain structure of 7.5W alloy.
This is considered to be due to the presence of γ´ precipitates and oxide dispersoids at the grain boundaries and at triple junctions, which effectively pin the grain boundaries and restrict the grain growth.
Additionally, ultrafine grains are formed due to the pinning of oxide dispersion and γ´ precipitates [12].

The preform was taken out of the substrate after deposition and then samples were cut from different locations of the preform as shown (with assigned number) in Fig.1.
Fig. 1 Locations of samples (with assigned number) cut from spray deposit for porosity, microstructure and hardness measurements.
The aluminum grain size is about 5-20 mm at peripheral region.
Wherever there is lead phase along the grain boundary, the width of the grain boundary increases due to the spread of lead on rolling.
The Pb phase is located mainly at the grain boundaries and the width of the grain boundary increases due to the spread of lead on rolling. 2.

Furthermore, these regular units are composed of finer sub−grains.
In addition, for a great number of cavities, the average size is very small, the density is high and the distribution is uniform.
Furthermore, each ferrite 3 sheet with regular external shape is composed of a large number of very small and equiaxial sub−grains with the average diameter of about 30 nm.
Furthermore, all sub−grains possess a narrow size distribution.
In special, the grains of containing Ni steel have a high dislocation density [4] .

One of the benefits of the fine grain approach is that one can apply fine grain process to existing alloys such as Ti-64.
(1) Grain Size: Fine grain size is essential for accelerating grain boundary sliding, which is a predominant mechanism of superplasticity.
According to a simple math calculation, reducing grain size by half results in doubling grain boundary area [1]
From the viewpoint of superplasticity, a grain boundary between two alpha grains is a limited contribution to grain boundary sliding.
Mater., vol. 433 (2010), p.49 [4] US Patent Number US 6,786,985 [5] US Patent Number US 8,551,264 [6] H.

Some �-Si3N4 grains are converted into columnar £ -Si3N4 grains with a high aspect ratio, and improve the fracture toughness of the new silicon nitride ceramic tool.
The additives were yttria (Y2O3) and lanthana (La2O3) with a grain size of 1.0-1.5 µm.
Then the �-Si3N4 grains grew into columnar grains in one crystalline direction at the high fabrication temperature.
The tool-life by fracture was measured with the impact number on the tool tip before tool fracture.
Three inserts for each tool material were used and the average impact number was then taken and plotted in Fig.3.

If the new orientation is accepted, the site may belong to other grain, otherwise the site belongs to the old grain.
Most grain-growth models incorporate the applied pressure effect on grain growth indirectly through density.
Q is the activation energy for grain growth.
And L is grain size.
The simulation time is expressed in term of the number of Monte Carlo Steps (MCS).

With the development of west of China being advanced, capital construction and hydroelectric project in high altitude areas of southwest China were put into effect, leading to an increasing number of engineering matters due to moraine soil [1].
Fig.11 is a reveal surface of moraine soil near the sampling site, and Fig.2 is the grain size distribution curve of samples after CT scan.
As shown in Fig.2, the grain size distribution of samples is very wide, and the content of silt and clay is about 45%, and the coarse grain content (grain size≥5mm) is about25%, while the coefficient of uniformity Cu=614.3, the coefficient of curvature Cc=0.0451.
After that, by calculating, the real numbers of perimeter (mm), area (mm2), length of long axis (mm) can be conversed from the pixels numbers.
The other reason is that the density between stone particles and fine grain is different but this is not taken into consideration in stone area ratio calculation.

This is a remarkably high elongation for a metallic sample having an hexagonal close-packed crystal structure where there are only limited numbers of active slip systems.
For the Al-3% Mg alloy the grain size is significantly smaller than in pure Al but again there is rapid grain growth at temperatures at and above ~500 K.
Fig. 6 Elongation to failure versus number of passes in ECAP for an Al-3% Mg-0.2% Sc alloy after ECAP (open points) and after ECAP + CR (solid points) [19].
An example is shown in Fig. 6 where samples of an Al-3% Mg-0.2% Sc alloy were processed by ECAP at room temperature for various numbers of passes, ground to give two flat parallel surfaces and then cold-rolled (CR) to a thickness of 2.2 mm [19].
Langdon, Twenty-five years of ultrafine-grained materials: Achieving exceptional properties through grain refinement, Acta Mater. 61 (2013) 7035-7059

Diamond grains are type II industry grade and consist of average grain sizes of about 180 microns.
This includes four influencing parameters, which are laser power, repetition rate, scanning speed and number of repetitions (Table 1).
Optical 3D microscope images of a tangentially laser touch dressed diamond grain before (left) and the identical grain after irradiation (right).
Most of the grains exhibit a similar behavior within the cutting process, which only affects the top portion of the grains.
To investigate the graphitization of the diamond grains, Raman spectroscopy is executed on the cut grain section (Fig. 3).

Also, the electrical conductivity decreased with increasing numbers of ECAP passes.
However, the uniform elongation increases from 0.75% up to 2,5% with the number of passes.
Langdon: Principles of ECAP as a processing tool for grain refinement.
Langdon: The principles of grain refinement in ECAP.
Manesh: High-strength, high-conductivity ultra-fine grains commercial pure copper produced by ARB process.