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It is important to note that these trends may be noticeably dependent on the number of ECAP passes [5-7].
A coarse-grained Cu-0.2wt.
Dependence of HAGBs on the number of ECAP passes.
This softening may be related to the increase in the spacing of HAGBs at approximately constant subgrain size with increasing number of ECAP passes, resulting in the fraction of low-angle grain boundaries decreasing considerably (Fig. 5).
Both alloys show increased ductility with increasing number of ECAP passes (Fig. 3).

The elongated LPSO phase grains and Mg worked grains (Mg-WG) are aligned along the extrusion direction, and tiny Mg recrystallized grains (Mg-RX) exist between them; the so-called multimodal microstructures [3] were developed.
Note that the microcracks were formed only in the LPSO-phase grains, as indicated by arrows in Fig. 5.
As increasing in the applied strain, the number of microcracks increased, leading to the macroscopic fracture of the specimen.
This strongly suggests the importance of the Mg grains, especially Mg recrystallized grains, acting as a ductile phase inhibiting the development of microcracks into larger cracks that lead to fracture.
This work was supported by the Japan Science and Technology Agency (JST), CREST (grant number JPMJCR2094), Japan.

Therefore, many researchers have focused on how to form a high number of nano-sized precipitates in the matrix.
On the other hand, the allotriomorphic ferrite was decorated along the prior parent grain boundaries and grew into the interior of austenite grains as the steels were isothermally held in the dual phase (α+γ) region.
The martensite was surrounded by allotriomorphic ferrite grains because martensite formed from the austenite grain when the steel was quenched to room temperature.
The average grain size was measured using the linear intercept method, counting more than 100 grains for each condition.
This result also corresponds to a high austenite decomposition rate due to the low number of carbon atoms that needed to be ejected from the parent austenite.

This wire tool with resinoid diamond grains (grains diameter about 20~40µm) is used to cut silicon ingots.
The abrasive diamond grain should be the same size as the SiC grain being used in free abrasive wire sawing.
In the manufacturing process, diamond grains are first stirred into SiC grains.
After selecting factors, their desired number of levels is determined.
The smaller grain size, the better kerf width.

A large number of black lumps disperse in the austenite matrix.
The analysis of the morphology of grain boundary carbide.
From Fig.2 a) and Fig.2 b) it can be seen that a large number of carbides disperse on the grain boundary of the original high-manganese steel, but only a small amount of carbide exist on the grain boundaries of high-manganese steel reinforced by nano-SiC Master Alloy .
The toughness of high manganese steel improves because that there is a large number of second phase presence in the matrix to pin dislocations and hinder the movement of grain boundaries.
The microstructure of ZGMn13Cr2 improve significantly when added the nano-SiC master alloy, additional the grain boundary carbides reduce significantly, and a large number of hard second phase grains disperse on the matrix. 2.

Mn doping had a more significant effect on the grain boundary than on the grain, suggesting that the grain boundary was more resistive than the grain.
The reduction in breakdown voltage (Vb) from 545 V (sample with 0.0% mol of borosilicate frit) to 188 V (sample with 3.0% mol of borosilicate frit) can be clarified by the increase of the average grain size from 5.7 μm (sample with 0.0% mol of borosilicate frit) to 29.3 μm (sample with 3.0% mol of borosilicate frit), resulting in lower numbers of grain boundaries for the sample with 3.0% mol of borosilicate frit and reduced p-n junctions.
The V-I nonlinear behavior of the varistor samples is a phenomenon of the grain boundaries between semiconducting ZnO grains.
The varistor breakdown voltage is directly proportional to the grain boundary number per unit of thickness and therefore to the inverse of the size of ZnO grain.
We suggested that the reduction in resistivity can be attributed to the reduced potential barrier between the ZnO grains resulting from a significant growth of grains in the samples after increasing doping amounts, which lead to a decrease in the number of grain boundaries between the ZnO grains and therefore reduced potential barrier.

Under the condition of applying heat pipes, the number of dimple gradually increased and the tensile rupture pattern was ductile-brittle fracture.
To achieve more grain refinement the grain growth has to be minimized.
By calculation, the grain size of the base material is Grade 9.
In the air condition, the grain size in weld nugget zone is Grade 10.
Under the condition of the heat pipes, the number of dimple gradually increases and the tensile rupture pattern is ductile-brittle fracture.

It has been found that although the microstructures of the three forging parts are all composed of α-Mg and β-Mg17Al12 phases, their shapes, sizes, numbers and distributions are all different, which also influences their mechanical properties.
In the subsequent grain growth, it was hindered by the near grain growth and did not form a coarse dendrite shown in figure (a).
The number and size of these liquid islands depend on the isothermal time under semi-solid temperature.
When the isothermal time is short, there are more liquid islands in the grain of α-Mg.
The other liquid in the primary α-Mg grain does not participate in the deformation.

There is a general consensus that the CET occurs when the moving front of columnar grains is blocked by equiaxed grains growing in the undercooled liquid ahead of this front, i.e. if the equiaxed grains are sufficient in size or number to arrest columnar grain growth.
Regardless of the blocking mechanisms, experiments and theoretical models have shown that the CET is significantly affected by the number of equiaxed grains and the nucleation undercooling.
Under grazing light, the resulting map shows the α(Ti) grains, i.e. the grains formed through peritectic reaction/transformation in the deep mushy zone of the sample, see Fig. 3a.
Grain structure of a CET sample prepared by power-down technique at a cooling rate of 30 K/min: (a) columnar and equiaxed α(Ti) grains in the vicinity of CET, (b) columnar and equiaxed β(Ti) grains in the vicinity of the CET.
It is clear that the α grain structure of the sample differs significantly from that of the primary β phase grains.

Because of this, weld property is improved , effect of precipitation strength is strong and can refine grain.
Laminar fine ferrite grains is obtained in the subsequent rapid cooling process.
The grain size is very small obviously, as figure 2 shows.
Large number of nanometer particles can be observed in the experimental steel.
As show in Figures 4 and 5, we can see a large number of nano-size precipitates containing Ti in the finished steel.