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The experimental results show the grains become smaller and aggregation of PbxNdy become severe as the content of Nd increases.
Fig. 1 illustrated that the grains of Pb-Nd (0.1 wt.%) were slightly smaller than Pb, and the morphology was irregular.
When the content of Nd reached 1.0 wt.%, the grains became smaller sharply, and large number of black site emerging which turned out to be PbxNdy (intermetallic compounds).
Evidently, Pb-Nd alloy grain size is determined by the content of Nd, the grains becoming smaller drastically with the increasing of Nd.
When the Nd content increased to 2.0 wt.% , the intermetallic compounds transferred to the grain boundary and aggregated severely.

A number of installations for electric discharge sintering of powder materials is developed.
This ensures complete safety of dimensions and operating characteristics of diamond grains.
However, such an information would be useful for the determination of the character of tool's work and for research of influence of binder's structural components and the state of abrasive phase (diamond grains) on tool's efficiency.
Sn (M2-01), conditional concentration of the diamond grains - 12.5 %.
From results of tests (Fig. 8) it is seen the following conclusion: the elements made with diamond grains, which were processed by hydrogen, have the increased abrasive capability (~70×10-3 g/(cm2 min))in comparison with the elements, containing the conventional diamond powder (~50×10 3 g/(cm2 min)).

Introduction Materials of sub-micron grain size (nano-grains) are characterized by high strength at ambient temperature, which is accompanied by high ductility and the high-speed superplasticity flow [1].
Severe deformation leads to refinement of the grain size and improves also the mechanical properties of the processed materials.
Copper samples, pre-deformed by the following number of passes: 1 (ε = 1.15), 4 (ε = 4.6), 6 (ε = 6.9), and 8 (ε = 9.2) by ECAE route C, were cold rolled to up to a 95 % reduction in area immediately after pre-cooling in liquid nitrogen (77 K) before each rolling pass.
In our experiments of cold rolling of Cu sheets, which have been differentiated by grain size, we found the maximum elongation was for cold rolled small grain size (30 µm) copper sheet, pre-deformed by ECAE up to ε ~ 8 (8 passes).
Microstructure of copper samples rolled up to z = 70%: CG - coarse grained (300 µm), SG - small grained (30 µm) and SGE8 - small grained after 8 passes of ECAE.

When the cooling rate is 0.1℃/s, a large number of ferrite can be seen in the microstructure of the sample, which is polygonal in shape, and the average grain size of ferrite is about 10μm.
Only granular bainite can be observed in the microstructure, and the grain size is relatively small.
When the cooling rate is low, the grain size is larger and the ferrite and bainite grains can be seen obviously.
With the increase of cooling rate, the grains are refined.
The ferrite grains are dark black, and the bainite grains with island and lamellar structure are gray white.

The green compacts were densified with grain growth to 76 - 99 % relative density.
At a pH below the isoelectric point (pH 2.5), the number of positively charged SiOH2+ sites becomes greater than that of negatively charged SiO - sites.
The microstructures consisted of SiC grains of small aspect ratios.
The average grain size, measured on 200 grains, is shown in Fig. 7.
The grain size of SiC was smaller for the addition of smaller R3+ ion

Dabhade et al [7] reported that the mechanism for powder metallurgy could be volume diffusion or grain boundary diffusion or the simultaneous occurrence of both.
For the densification process in a traditional powder sintering method, grain growth and neck growth are the critical mechanisms that achieve densification.
However, with continuous high-pressures being applied and ultra-fast forming time, Micro-FAST occurs without the coarsening of grains during the densification process.
Vasylkiv, Grain boundary diffusion driven spark plasma sintering of nanocrystalline zirconia, Ceram.
Shan, Blanking clearance and grain size effects on micro deformation behavior and fracture in micro-blanking of brass foil, Int.

Further milling gives rise to a continuous decrease in grain size and destabilization of the crystalline structure occurs by an increase of the number of structural defects such as vacancies, dislocations, local stresses and grain boundaries.
The diffraction pattern (Fig. 3(a)) taken from the area A in Fig. 2(b) indicates that these nano-sized grains are mainly α-Fe grains.
And the spotty diffraction rings (Fig. 3(b)) taken from the area B in Fig. 2(b) confirm that these nano-sized grains are mainly Si grains.
And the grain size remains in the nanometer region, which is also been seen in Fig. 5(a).
And the grain size of the Fe3Si remains in the nanometer region.

The investigated material in its initial state was characterized by a coarsegrained structure (the matrix's grain size was in the range of 100 to 500 microns) (Fig. 6).
Results of the EBSD analysis of the investigated MgAl2Si alloy, a) area fraction distribution of the grain size, b) number fraction distribution of the grain size Results of the SEM evaluation indicates that at the initial stage of the cavitation destruction tested on the vibration stand, a prominent effect of plastic deformation is visible on the surface of the MgAl2Si alloy (Fig. 7a).
Increasing of the exposition time leads to a formation of erosion pitting and number of cracks.
The MgAl2Si alloy damaged surface that is characterized by an increasing number of deep craters is rapidly eroded by the chipping of very small fragments of Mg2Si intermetallic precipitates (Fig. 9d).
Subsequently, craters are formed on phase boundaries; they depth increases as a result of the spallation of whole grains.

The face-centered cubic copper with a good plastic property is easy to deform and produces a large number of dislocations in a short time, leading to the refinement of crystal grains and the very close approach to the limit of energy conversion.
Because the crystal boundary can hinder the deformation of crystal grains, once exceeding the limit, the energy no longer increases, and the chance of grain refinement dwindles as well[11].
As milling time increases, the grain size gradually decreases and the specific surface area enlarges rapidly.
At the same time, the number of atoms at the surface is on the rise and the surface energy rapidly increases with the large specific surface area.
As milling time increases, crystal grains are continuously refined.

The average grain size was 7.73 μm and the maximum grain size was 60 μm.
The result was micronized marble powder (MM) with a mean grain size of 5.35 μm and a maximum grain size of 40 μm [9].
Figure 2: The grain fineness curve of marble sludge and micronized marble powder [9].
In the next steps, finer sandpaper was used with a coarseness of 500 grains/cm2 for 2 minutes and 1200 grains/cm2 for another two minutes both at a pressure of 30 N.
Depending on the water–cement ratio, the number of pores created by the water drying and the bulk density resulting from this factor.