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The grain boundaries are well-defined and the grains are reasonably equiaxed suggesting that recrystallization took place during the extrusion at 380 oC.
Only after 1-pass ECAE, large portion of the grains were substantially refined, so that the grains became less resolved to the optical microscope.
Some elongated coarse grains with grain size above 10 µm still remained in the alloy.
A number of twins were observed within these coarse grains.
With increasing ECAE passes, the small grains were further refined, and the area fraction of coarse grains and their average grain size decreased.

The following results were found: - As larger amount of cold work can be applied by HPTR cold pilgering, a lower number of intermediate heat treatments are required.
The impact on the grain size, precipitates, hardness and texture is investigated.
In contrast, a larger amount of cold work can be applied by HPTR cold pilgering (several cumulated passes) coupled with a lower number of intermediate heat treatments
Grain size measurements are performed by using image analysis (Visilog software).
Several thousand of grains are analyzed in each case.

Table 1 Information of two commercial α-Al2O3 powders available from suppliers Series number Average grain size/nm Purity/wt% Supplier 1 150 99.99 TM-D,Taimei Chemicals Co.
The average grain size is determined by linear intercept method using equation 1 according to reference [10]: (1) where C, M and N is length of line, magnification and the number of intercept point, respectively.
Influence of sintering temperature on grain size of Al2O3 ceramic.
At a sintering temperature of 1250 °C, the average grain size is 1.25 µm.
The average grain size is 4.65 µm for a sintering temperature of 1400°C.

Therefore, a large number of methods have been explored in recent years, in order to obtain higher strength and toughness of the magnesium alloy.
It can be seen that the microstructures are the equiaxed grains with the average grain size of 3.4μm, but the average grain size of AZ31 alloy prepared by the same process is 5.6μm [4].
When the dislocation pile up to a certain extent will rearrange and combine, producing dislocation cells and sub-boundaries, sub-boundaries further transforms into high angle grain boundary, and ultimately into the recrystallized grains with high angle grain boundaries.
Although the grains slightly grow up along the stretching direction, but still are equiaxed grains, which indicates that the grains growth and movements that along the grain boundaries are isotropic and GBS is the main deformation mechanism of AZ31+Sr+Y alloy during the superplastic deformation process.
When temperature increases to 400℃, the fracture morphology exhibits a large number of dimples and tear ridge which connecting dimples (as shown in Fig. 7d), proving that the fracture mode changes from microviod accumulation fracture to intergranular fracture.

Grain size refinement by using equal channel angular Extrusion (ECAE) is an effective way to improve workability and strength of the magnesium alloys.
The deformation mechanism of ECAE for grain refinement is obtained.
Especially, the relationship of material grain refinement and the deformation behavior needs to be studied further.
Five numbered nodes were marked onto the workpiece, these nodes a–e are placed on the cross-section, 1-1, in the die channel, respectively, as shown in Fig. 3, representing different zones in deformation.
Conclusions This paper presents interesting results concerning a dual analysis between finite element simulation and experiments for understanding and predicting grain refinement in ECAE.

In order to investigate effects of a grain size of the source diamond, EDM cutting experiments were conducted on the EC-PCD specimens of 4 different grain sizes.
In the case of S-PCD, the cutting speed for the 25µm grain size was lower by 15% or so compared with the10µm grain size.
In both cases of 10µm and 25µm grain sizes, surface roughness value of the EC-PCD was smaller than that of the S-PCD by 40% or so, and the EC-PCD of 25µm grain size after EDM cut showed the surface roughness identical to the case of the S-PCD of 10µm grain size.
In the SEM image of the S-PCD surfaces, a number of the pits created by preferential removal of the cobalt can be observed.
This phenomenon becomes prominent as the diamond grain size gets larger.

Crystal grain size and shape were evaluated by optical microscope.
The sheets were consists of equiaxial crystal grains.
Average grain size of 1, 2 and 3 ADB cycles was 20 mm, which is too large to induce a grain boundary sliding.
Tensile strength increased with increasing the ADB cycle number.
Vol. 210 (2010), p.751. ] due to fine crystal grain structure.

A number of reports on the effect of grain size in the manganites particularly La0.67Ca0.33MnO3 have been published [8,9] (and references therein).
The average grain size was estimated using the intercept method.
The electronic thermal conductivity ke can be calculated from the Wiedemann-Franz law, ke = sLT, where s is the electrical conductivity, L is the Lorentz number = 2.45 ´ 10-8 W W K-2, and T is the temperature.
Previous works on smaller grain size (1 to 10 µm) do indeed showed that the thermal properties depend on the grain size.
Hence we conclude grain affected the thermal properties for smaller size but not for larger grains.

When the welding current is more than 125A, the grains coarsen sharply, and the number of precipitates and defects increase obviously.
The microstructure of the WZ are equiaxed grains and the precipitation of second phase along grain boundary makes the hardness of grain boundary higher than the crystal, thus, the hardness of the WZ is higher; grain coarsening of the HAZ makes the hardness decrease during the welding thermal cycle.
(2) The FZ is composed of fine equiaxed grains.
The grain size of the HAZ is coarse because of overheating.
With the increase of welding current, the grain size of the HAZ remaines relatively stable.The BM consists of fine equiaxial recrystallization grain size

The work indicates that the recrystallized grains, which migrate into the deformed grains, are mainly with the high misorientation angles.
The large percentage of the recrystallized grains, whose misorientation angles with deformed grains exceed 15°, are corresponding to the {111} transformation texture.
From picture, we can see that almost all the recrystallized grains and deformed grains were separated by high angle boundaries (>15°).
The {110} grains have the highest stored energy, but since this texture component is very weak, the number of nuclei produced is small.
(3) The migration of recrystallized grains into deformed grains is difficult to proceed if the misorientation angles are less than 15°.