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Besides, the TiC phase also detected throughout the experiment with increasing in temperature resulting the decrease in number and increase in size.
The movement of the grain boundary has implications for recrystallization and grain growth of alloy.
Other researchers reported that TiC particle was increase in size and decrease in number with the increase in solution treatment temperature [7].
Grain growth take place by the migration of grain boundaries via atomic diffusion across boundary resulting enlarge of grains.
Solution treatment at 1200 ºC shows the austenite grains grow up abnormally to a size of 100.88 μm with decreasing the hamper of grain growth.

With the number of a-Si3N4 grains increased, the weight loss decreased gradually.
With the number of a-Si3N4 grains increased, the linear shrinkage gradually decreased.
Therefore, as the number of a-Si3N4 grains increased, the linear shrinkage decreased gradually.
Although the size of the β-Si3N4 grains was relatively small, the number of the rod-like β-Si3N4 grains with a high aspect ratio was small.
Therefore, the distribution of β-Si3N4 grains size was relatively even, and the number of coarsened β-Si3N4 grains was relatively small.

A commercial spray-cast aluminum alloy, having a composition of Al-11.5% Zn-2.5% Mg-0.9% Cu-0.2% Zr, was processed by equal-channel angular pressing (ECAP) to give an ultrafine-grained microstructure with a grain size of ~0.3 µm and a fracturing of the rod-shaped MgZn2 precipitates.
Introduction Equal-Channel Angular Pressing (ECAP) has now become established as an effective method to achieve an ultrafine-grained microstructure [1-3].
Firstly, processing by ECAP, for example by 6 passes at 473 K, significantly reduces the grain size from ~2.1 µm to ~0.3 µm [6].
It is also noted that an increase in the number of passes from 6 to 8 leads to a shift in the optimum strain rate so that the maximum elongation occurs at a faster rate.
Fig. 2 Elongation to failure versus initial strain rate for the Al-7034 alloy at 673 K after processing by ECAP at 473 K for different numbers of passes.

In grinding process, the point that enables to become a cutting-edge is only the highest point of grains.
Therefore, it is thought that the grains are maintained on the working surface, and then, the cutting-edge is generated on the top of those grains.
Since the grains are maintained, with progression of dressing, internal grains are exposed to the peripheral surface.
In other words, in case of less number of spark-out, since the grains damaged with dressing remain on the working surface, the shedding tends to occur with grinding.
This indicates that there is the critical value for the spark-out number in dressing.

The reaction between the zinc plate (ZP) and the IF steel with near surface ultra fine grains (NSUFG) structure with grain size of about 89 nm was studied in temperature range of 473K to 623K in order to elucidate the temperature dependence of the reactions and its mechanism, by comparison with the reactions of ZP to coarse grains (CG) sheet, superficial cold rolled CG sheet (CG+R) and superficial cold rolled NSUFG sheet (NSUFG+R).
On the other hand, small number of nuclei are formed at small number of sites on the CG/ZP interface, and they slowly grow and take much time to connect to each other with limited mass transfer mainly by volume diffusion, resulting in the thin reaction layer in the shape like stone wall.
Thereby the cracks are yielded among the ultra fine αFe grains in the NS-UFG layer as shown in Fig.1c3-d3 and Fig.6b, and the ultra fine αFe grains are surrounded with the 1Γ -phase and/or 1δ-phase, and they become free from the αFe matrix just like a group of islands, after the grain boundaries are entirely covered with the 1Γ -phase and/or 1δ -phase.
By further annealing, the free ultra fine αFe grains decrease their size and number due to the dissolution to the 1Γ -phase and/or 1δ -phase.
Summary The reaction of zinc against IF steel with NSUFG structure with grain size of about 89 nm was studied in temperature range of 473K to 623K by using ZP on coarse grains (CG) sheet, superficial cold rolled CG sheet (CG+R) and superficial cold rolled NSUFG sheet (NSUFG+R).

A large number of sub-crystals remained on the surface of the thick plate and was accompanied by much recrystallization.
It can be seen that coarse particles are distributed in grains and along original grain boundaries.
After etched in chromic acid, the large white bright structure was recrystallized structure, and the non-recrystallized structure contained a large number of sub-grain boundaries.
Many recrystallized grains which had no red sub-grain boundary inside were formed between the original grains.
Otherwise, due to the high degree of deformation, a large number of substructures existed in the grain, Δσgb was high and dominant.

All the samples investigated in the present study show the presence of relatively large austenite grains, demonstrating that the number of active nucleation sites of austenite per unit volume is small.
Table 2 lists the average grain size, measured after applying DAAS, the average number of kish graphite per unit area, and the size of the larger eutectic cells.
In addition, there is a considerable number of primary (kish) graphite particles inside each austenite grain.
Table 2: Average grain size, average number of kish graphite and eutectic cells per unit area for samples A, B and C.
The nucleation of austenite appears to be independent from the prior precipitation of proeutectic graphite, as the density of kish graphite particles is much higher than the number of grains of austenite.

For those film with a greater grain size, the remagnetization processes take place due to the non-coherent magnetization vectors rotation and DW displacement in the grains.
The films thickness D was calculated using the value of the mass per unit area of the deposited material , where ρ is Ni density, I is a current density, t is a deposition time, M is Ni molar mass, z is valence number of ions, F is Faraday constant.
The grain size influences the roughness of a surface.
Thus, in films with grains less than 400 nm the magnetization reversal processes are carried out by incoherent rotation of the magnetization vectors in different grains.
If grain size becomes more than 400 nm, the magnetization reversal is mainly due to the domain wall motion in the grains.

The samples were pressed for various numbers of passes up to a maximum of 24 corresponding to a maximum imposed strain of ~24.
The retention of a constant grain size with increasing numbers of passes is consistent with a model for grain refinement in ECAP [19].
The grains were essentially equiaxed after 4 or more passes although a slightly more uniform distribution of the Zn-rich and Al-rich phases was achieved after pressing through large numbers of passes.
N is number of ECAP passes.
Grain refinement in both alloys showed saturation after 4 passes of ECAP. 2.

XRD, FESEM and EDS results showed that a large number of fine TiB2 platelets were uniformly embedded in irregular TiC grains, a few Cr-Al metallic phases or in between those phases.
FESEM images and EDS results showed that a large number of randomly-orientated, fine TiB2 platelets (presented by the dark areas in Fig. 2) were uniformly embedded in the irregular TiC grains (presented by the grey areas in Fig. 2) and Cr metallic phases (presented by the white areas in Fig. 2), and a few inclusions of α-Al2O3 were also observed, as shown by the isolated black particles in Fig. 2.
Hence, rapid growth of TiC is the other reason for the achievement of fine-grained microstructures in current TiC-TiB2 composites.
According to the literature [9], larger is grain size of TiC grains, smaller is the critical shear stress inducing the cracking of TiC grains, so transcrystalline fracture almost takes place in the irregular coarsened TiC grains.
XRD, FESEM and EDS results showed that a large number of fine TiB2 platelets were uniformly embedded in irregular TiC grains, a few Cr-Al metallic phases or in between those phases, and a few of isolated irregular α-Al2O3 inclusions were also detected in the ceramic, whereas Cr-Al metallic phases were also concentrated at central part of the sample.