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The grain size affects the amount of oil carried during operation.
The final customer specifies the coating thickness, grain size, and grain quantity on the piston surface.
The grains are evenly distributed on the surface, without any gaps.
The grains are evenly distributed across the surface without any gaps.
Additionally, the difference is visible in the number of elements detected on the piston surface.

Moreover, the grain resistivity of BaTiO3 ceramics with Sm2O3 additive changes according to the temperature variation, meanwhile, the NTC effect presented, furthermore, the resistance of grain is far lower than that of the grain boundary, leading to PTC effect presented.
The microstructure and grain size were characterized by JEOL JSE-649OLV Scanning Electron Microscopy (SEM).
It can be seen clearly in figure.1a that the grain growth is not obvious without Y2O3 additive, and there’re apparent holes during the grains, these holes make the electronic migration difficult, leading to increasing the room resistivity, when the amount of Y2O3 additive is 0.02%(mole fraction), the grain growth improves to some extent, decreasing the number of hole during grains as is shown in figure.1b, moreover, as Y2O3 content continuously increases, figure.1c shows that the grains keep well touch with each other without obvious holes during them, when Y2O3 content further increases, the resistivity first increases and then decreases.
The SEM morphology of the honeycomb ceramics sintered at 1600ºC for 5h as Y2O3 additive varies from 0.00% to 0.10% (mole fraction) thus it shortens the transportation of the electrons by decreasing the amount of grain boundary, resulting in the corresponding room resistivity decreasing from 6.4×104Ω.m to 5.5×101Ω.m, declining by 3 order of magnitude, in figure.1e, few glass phase is observed in the morphology of the sample, and it blocks the grain boundary , which plays the role of electron channel, resulting in decreasing room resistivity conversely, the number of glass phase increases sharply with 0.10%(mole fraction) Y2O3 additive, figure.1 shows that the morphology of the samples represents as river pattern, leading to the electrical properties further deteriorating inevitably，as a result, the corresponding room resistivity increases from 1.2×103Ω.m to 9.4×103Ω.m.
When the content of Y2O3 is further up to 0.08 %( molar ratio), some Y3+ ion is situated in oversaturation, part of which is adsorbed in the grain boundary, due to the trend that Y3+ and Ti4+ capturing electrons can change into ions with low valence, the energy barrier at grain boundary decreases, promoting the formation of glass phase as is shown in figure.1e and figure.1f, leading to the decreasing room resistivity of the samples.

Meanwhile, it can be seen that a number of newly refined grains are observed, indicating that dynamic recrystallization (DRX) occurs in evidence during hot compression deformation.
Compared with deformation microstructure at deformation temperature of 800°C, which the formation of new recrystallized grains was seen to occur in the interior of original grains and along the original grains boundary, the recrystallized grains of 750°C were developed only along some initial grain boundaries and no new grains were observed inside the original grains under optical microscope (Fig. 2b).
Recrystallized grains Elongated thin grains b Compression direction a Grain growth d Elongated thin grains Recrystallized grains c Fig.2 Optical microstructures of the solution-treated alloy (a), and the hot-compressed samples with temperatures of (b) 750°C, (c) 800°C, and (d) 850°C.
Meanwhile, the dynamic recrystallization process generates a number of nuclei, which originate at the old grain boundaries, with various orientations.
In the present study, as seen from the microstructure development in different deformation temperature, the microstructure are consisted of elongate and flat grains which show the DR features and DRX grains originated at the boundaries of deformation grains in case of 750°C deformation temperature, and deformation grains and DRX grains in the interior of original grains and along the original grains boundary in case of 800°C, and deformation grains and DRX grain growth in case of 850°C.

Epitaxial growth of the grains from a given layer on the grains formed during the solidification of the previous layer may also occur [3-7].
The resulting microstructure hence exhibit elongated grains that are roughly parallel to the building direction.
Fully austenitic grains can be identified from the EBSD map (Fig. 4(b)).
These grains are elongated following the building direction.
On the one hand, the occurrence of epitaxial growth of the grains from a given layer on top of the previously solidified layer led to a microstructure characterised by elongated austenitic grains roughly parallel to the building direction oz.

Energy spectrum analysis for grain boundary and intracrystalline of liquid forging indicates that: liquid forging has micro-segregation, mainly Cu, Fe, Mg and Mn such elements in the form of compounds gathered at the grain boundaries, resulting in a grain and grain boundary ingredient uneven, where Cu and Fe segregation is especially remarkable.
The compounds band width is much thinner and the numbers much less in the part shape under the pressure of 90Mpa than that of pressure 80Mpa.
Thus, the segregation extent in the liquid die forging part shape under the pressure of 90MPa is lower than that of 80Mpa part, the grain also significantly more fine.
It can be obvious observed from the high and low organization figure that: liquid forging can forming flange blanks without shrinkage, porosity, loose and other casting defect; And improved the organization, refined the grain.
The latter is under the action of the pressure, the crystallization hard shell of the liquid metal or liquid forging part and cavity wall close contact and improve heat exchange between liquid metal and concave die, accelerate the solidification of the liquid forging parts, and because the effects of pressure increased the crystallization point of metal, increases the degree of supercooling, improve the nucleation rate, plus the dendrite crushing and fall off, the nucleation number also greatly increase, thus refined the grain, which has obvious grain refinement for thin liquid forgings.

Size of former austenite grains conforms scale ranges № 5, 6.
While raising nickel content up to 0.33 – 0.54% austenite grain size didn’t change.
Sample number The contamination by nonmetallic inclusions, raiting Size of austenite gaine, raiting Size of martensite needles, mcm non-deformable silicates (fragile) Oxides spot 1 2b, 2a, 3a 1a 5, 6 7-10 2 1b, 2b, 3a 1a 5, 6 4-8 3 2b, 3a 1 a 5, 6 5-8 4 2b, 3а (1b) 1 а 6, 5 2-5 5 1b, 2b, 3a 1 a 6, 5 2-5 6 1б, 2b, 2a 1 a, 2a 6 2-4 7 1b, 2b, 3a 1 a 6 2-5 8 1b, 2b, 3a 1 a 6 2-4 Increasing the content of nickel up to 0.65% (sample №4) greatly grinds martensite needles, and reduce size of former austenite grains.
Size of former austenite grain conforms №6.
Per the results of calculations obtained dependencies, the adequacy of which was checked by actual values in index of the average approximation error: , (1) m - the number of observations; – calculated value of resulted index; – real value of resulted index.

The results show that AZ61 alloy with Y addition can refine grain size of the matrix and alter the distribution of the phase β-Mg17Al12 from continuous network morphology transition to small and dispersive distribution along the grain boundary by forming the second phase Al2Y which has a high melting point.
When adding 0.5% Y, the morphology and distribution of β phase began to change from continuous network to semi-continuous network, and also a small portion of the block-like phase can be observed in Fig.1(b); When Y addition reached 1.0%, β phase was more evenly dispersed along the grain boundary accompanied by the growing number of block-like phases in Fig.1(c);When adding 1.5% Y, the block-like phase show a tendency to grow up which therefore segregated the matrix and restrict the refining effect of the grain.
It can also be observed that the second β phase begin to show a tendency of network structure while the grain size is coarse in Fig.1(d). 25μm (a) (c) 25μm (d) 25μm (b) 25μm Fig.1 Microstructures of Mg-Al-Zn-xY alloy (a)Without Y (b) 0.5% Y (c) 1.0% Y (d) 1.5% Y SEM morphology of as-cast AZ61-1.0Y alloy(Fig.2) show that AZ61 alloy comprises α-Mg matrix, β-Mg17Al12 phase and a block-like new phase; corresponding EDS analysis presents that the block-like new phase is enriched with Al and Y.
These compounds containing rare-earth phase usually have a high melting point, thereby preventing the growth of grains made the grain refinement, while Y made the β phase change to granular and evenly disperse in the matrix.
Alloy Ecorr (mv) Jcorr (mA·cm-2) 1# AZ61 -1413 2.1427 2# AZ61+0.5Y -1428 1.8835 3# AZ61+1.0Y -1450 0.6923 4# AZ61+1.5Y -1430 1.0496 Conclusions 1) Addition of Y to AZ61 magnesium alloys can refine grain, make β-Mg17Al12 phase change from the continuous network-like structure into the dispersed distribution, and a high melting point Al2Y new phase forms. 2) The corrosion current density of alloy 3# is 0.6923 mA·cm-2, only 30% of that of AZ61 alloy.

The α laths appear to be coarser at the interior of the grains and finer in regions adjacent to the grain boundaries.
In the LM image a dark phase can be seen formed along the β grain boundaries and as precipitates within the grains.
The distribution and number of precipitates within the grains is inconsistent.
However, there is significant contrast at the grain boundaries and so the grains in general are easily discerned.
The STA sample has a more uniform dispersion and greater numbers of the fine lath like α precipitates, which are the greatest contributors to strengthening.

Ratio of cadmium to thiourea molar is 0.1:0.05 as an indication of nanostructured CdS formation with a grain size of 3.83 nm CdS nanostructures have been characterized by scanning electron microscopy (SEM) to research the morphology, respectively.
A better understanding of matter at then a no scale has led to a number of advances in materials science having novel optical and electronic properties.
They have investigated the grain size, dislocaction density, strain, interplanar distance, miller indices, number of crystallites per unit area, lattice constants and bulk modulus of CdS nanostructures, and analyzed the thickness and optical properties transmissions, energy band gap, refractive index and optical dielectric constant where proved distinguished results compared with other ones.
Peak 2θ Grain Size (nm) Full width half maximum (FWHM) Lattice constants a and c (Å) 26.78 4.35 0.36 a=1.15 4.015a 2.35b 4.1c c=3.45 6.545a 7.04b 6.7c 29.38 3.83 0.42 a=1.04 c=3.13 Ramaiah et al. aRef. [7] Exp.; Lahewil et al. bRef.; [6] Exp.; Weast cRef. [8] Exp.
We determined that all samples surfaces are relatively smooth and uniform, having well defined nanosized grains with relatively small roughness values.

Sintered compacts showed a highly densified compacts (∼95% relative density) while retaining fine grains in the matrix.
There are number of advantages in using TiC as the reinforcement for Cu based composites.
TiC distributes uniformly in the copper matrix so TiC particle acts as a grain growth inhibitor during sintering process.
The hardness enhancement is attributed to the grain growth restriction by pinning of TiC at the grain boundary.
Acknowledgements This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 103.02-2011.49.