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The three steps are performed using diamond based slurries with decreasing grain size.
It is classified as homogeneous (one polytype, usually 3C-SiC) or heterogeneous (multiple polytypes) depending on the number of polytypes present in the wafer.
The intra-grain RMS roughness below 3Å was measured, but several nm high steps between adjacent grains have also been observed.
(a-b) large grain, heterogeneous poly-SiC substrate - note the grain boundaries and grain-to-grain variation of surface aspect.
(c-d) small grain homogeneous poly-3C-SiC substrate.

Nanocrystalline materials are called with the size of crystals (grains or particles) less than 100 nm [7-11].
In nanocrystalline materials, the fraction of the boundary layer increases rapidly when the grains are crushed from 100 to 4-5 nm.
Assuming that the grains are spherical in shape, and assuming a layer thickness of 1 nm (this corresponds to 2–3 atomic layers for most metals); we obtain the following relations between the grain diameter and the volume fraction of the surface layer [7].
Thus, the volume of the boundary layer becomes larger than the volume of crystals in nanocrystalline materials, starting from a grain diameter of 6 nm.
Sample № 2, obtained in an alkaline medium (pH ≈ 11) better absorbs water than sample №1, obtained in a neutral medium, which may be due to both an increase in the pore radius and an increase in the specific surface, i.e. pore numbers.

In the area without big grains or craters, ripples can hardly be found.
After irradiation, the impurities or defects turn into big grains or craters.
Raising the number of laser shots or pulse energy can both increase irradiation energy deposition.
Thus the ever-growing grains blur or even cover up the ripples in the ablated zone.
Maybe the weak irradiation intensity deposited on the area benefits the growth of grains.

Introduction Production of aluminium has been openly used for many fields accordingly aluminium recycling prompts as tremendous number of expenses and environmental benefits.
We can note that fine grains appeared in the microstructure of the samples preheated at 450 °C, which was because of the consequence of dynamic recrystallization during hot extrusion but chip boundaries and grain sizes are small, and no voids and cracks can be noted in these profiles.
At this temperature, the average of grain size at 1 hour and 3 hours is 18.59 and 24.77 μm respectively.
At 550 °C, the shape of grains become more equiaxed and recrystallized and showing that grain coarsening had occurred at this processing temperature.
The average grain size at 500 °C and 550 °C preheating temperatures were bigger than the grain size compared to the specimens preheated at 450 °C.

The ODS (Oxide Dispersion Strengthening) is dominant by Orowan Bypassing Mechansim and Grain Aspect Ratio.
Firstly, the superalloy is strengthed by Orowan Dislocation Arrangement; Secondly, a high Grain Aspect Ratio of a larger grain size improves stress-rupture life by thermal treatments and zone annealing.
In detail, the grain size, range from 30μm to 50μm, achieve desired combination of yield strength for resisting fatigue crack initiation.
Admittedly, the circuit potential, Ohm average and Potential dynamic Polarization reduces to a number which is lower than numerical value of Inconel 600 alloy [16].
However, due to the chemical oxidations of Ni-rich region, the cracks propagation around grain boundaries promotes cracks formation [17].

Similarly, grain growth during sintering could be monitored via this intensity ratio.
Compared to coarse grained materials, a different situation may occur in nanomaterials.
Similarly, volume concentration of triple points, Ct , is proportional to an average number of grains per unit volume (Ct ~ d −3).
This result is consistent with a grain growth picture suggested by LT data.
Becvar, Application of Maximum-Likelihood Method to Decomposition of Positron-Lifetime Spectra to Finite Number of Components, Mater.

The FT-IR spectrum of these materials was done by “Interspec 2020 FTIR spectrometer” spectro lab UK, over the wave number of 4000–400 cm-1.
FT-IR spectra of the various samples in the wave number range 4000-400 cm-1 are shown in Fig. 2.
It is apparent from the Fig. 4 (a) that salt grains have the average particle size is about 3 µm.
The first one being well conducting layer consists of bulk grains and the other one being the grain boundaries that are poor conductors.
The grain boundaries are found to be more prominent at lower frequencies, while the grains at higher frequencies [23].

Nomenclature Vw—workpiece speed(ms); VS—wheel speed(ms); Dw—workpiece diameter(mm); Ds—wheel diameter(mm); ap—grinding depth(μm); agmax—maximum undeformed chip thickness(μm); T—grinding temperature(℃)； NS—effective sharpening edges number per unit area in wheel； C—ratio of chip width and chip thickness, C=bgag; C0—constant; α—constant index of wheel speed; β—constant index of maximum undeformed chip thickness; i—greater or equal to 1 consecutive positive integers; λ—percent of experimental number n in one some error range to total experimental number N.
In the process of single grit grinding simulation, the grain stays no less than 0.01ms in grinding arc area, so the feed movement is not taken into account in simulation.
Meshing lc Face 1 Face 2 Face 3 Face 4 Face 5 Central axis Fig. 1: Meshing of workpiece Fig. 2: Boundary conditions setting The geometries of grain and workpiece must be assured not distorted when determining the number of grid.
Taking into account the simulation accuracy and calculation time, the mesh number of abrasive and workpiece is chosen as 50,000 and 150,000 individually.
Acknowledgement The authors would like to gratefully acknowledge the support from the Major State Basic Research Development Program of China ("973" Program) (Number: 2009CB724403), the National Science & Technology Major Project(Number: 2009ZX04001-101) and Key Subject Construction in Shanghai (Number: B602) References [1] C.

Roy et al. [4] studied (Ti, Nb-V-Ti) austenite grain growth in two microalloyed steels.
The addition of Ti reduces the change in grain size.
At this time, a large number of strip-shaped islands are intermittently and linearly distributed on the ferrite matrix, and the ferrite matrix has a striped substructure.
Because energy, composition, and structure fluctuations are prone to occur on the grain boundaries, crystal nuclei are first formed at the austenite grain boundaries, as shown in Fig. 8.
Pearlite will continue to grow into the austenite grains in the longitudinal and transverse directions.

A large number of pores, inclusions and other defects existed, which would affect the hardness and wear resistance of the coating.
Meanwhile, small amount of CeO2 adsorbed on the surface of the nuclei, hindering the grain growth, which effectively refined the coating and showed strong grain refinement effect.
Meanwhile, rare earth elements would easily segregate in grain boundaries, reducing the driving force of grain growth and refining the grain.
Grain refinement was conducive to the adsorption and diffusion.
In the vacuum melting process, rare earth atoms with larger radius would easily segregate in grain boundaries or phase boundaries, which increased the resistance of interface migration and effectively refined the microstructure.