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A fine-grained 90W-7Ni-3Fe alloy with high tensile strength and elongation properties was obtained, in which the tungsten grain size was 8-12μm, the maximum tensile strength was 1050 MPa and the elongation was 30%.
Both Ryu and our earlier studies have demonstrated that a nearly full-dense W-Ni-Fe alloy with 3-5µm grain size can be obtained via solid phase sintering [5-6] , but this accelerates grain coalescence which is accompanied by decrease of the sintered density during liquid phase sintering [7-8] .
With adding 0.04wt% of Y2O3 in the alloy, the number of tungsten grain transgranular fracture increases (as shown in Fig.4(b)), and the matrix shows obvious ductile rupture characteristics, which appears to be a nest-like shape (as shown in Fig.4 (c)).
The optical micrographs of the alloys in Fig.4 show the tungsten grain size and its distribution.
When Y2O3 was added, smaller particle tungsten grain that reprecipitated from liquid phase were found, causing the contiguity of W-W to decrease.

Effects to grinding wheel physiognomy by grain size and organization number were analyzed and grain distribution was visually represented.
A grinding wheel was supposed to be composed by massive, random distributive abrasive grains, and mathematical modeling started from abrasive grain modeling [2-4].
For one abrasive grain: ( )idd i fkdd += 10 (1) id is diameter of abrasive grain i (mm); 0d is average diameter of certain abrasive grains (mm); dk is grain diameter variation factor; dif is random uniform number generated by the computer.
Abrasive grains were supposed to be distributed equably in the volume of zyx lll ×× , so the number of abrasive grains contained in is N and N equals to: 3 0/6 dlllVN zyxg π = (3) gV is abrasive grain proportion of the grinding wheel (volume ratio between abrasive grain and grinding wheel).
The roughness of grinding surface related to the wheel-per-area-grain-number, grains distribution and tooth marks.

China Keywords: Photostriction, PLZT ceramics, Anomalous photovoltaic effect, Grain size Abstract.
To control the grain sizes of the PLZT ceramics to the same, a simple grain growth model (see Eq. 1) were applied to determine the different sintering periods for the different compositions.
Fig. 4 Contour map of photovoltage in PLZT system as a function of the composition when the grain size is controlled.
Grain size control.
It has been reported that the photovoltage generated has an inversely proportion with the average grain size [5] (see Eq. 2) V0 = Φg l / lg (2) Since the grain size dependence was excluded, the results above are the intrinsic property in the PLZT system, The photovoltage generated in a single grain of the PLZT 3.44/52.73/47.27, therefore, is the largest, suggesting that the product of the number of impurity levels and the asymmetry of materials of this composition reaches the maximum [6].

Softening level depends on both ARB temperature and number of cycles.
Fig. 2 shows the variation of ultimate strength and elongation with increasing number of ARB cycles at temperatures from 250°C to 350°C.
Fig. 2 Variation of ultimate strength Rm (a) and elongation (b) with number of ARB cycles of samples processed at 250 to 350°C.
It was found out that recrystallization and grain coarsening occurs during heating before ARB and by this the grain size keeps constant with increasing number of cycles.
Non-uniform grain size with coarser grains at bonded interface is observed in 0 30 60 90 0 1 2 3 4 5 6 7 number of ARB cycles I2 [%] positrons at defects (b) 0 60 120 180 240 300 0 1 2 3 4 5 6 7 number of ARB cycles lifetime [ps] free positrons at defects (a)samples processed by 2 ARB cycles.

During each extrusion, besides the large simple shear plastic deformation in a thin layer of a workpiece by moving through a die, the cross-section of the sample remains unchanged and consequently this procedure can be repeated a great number of passes, resulting in the accumulation of large strains of alloy.
Therefore, compared with the grain size pressed for 4 passes, the grains (Fig.2 (b)) grow up and trend to be coarse, at the same time the boundaries are more distinct and the grain are more equiaxed.
Recrystal grains grow up slightly and grain boundary is distinct owing to high tensile temperature and long tensile time.
The recrystal grains in Fig.4 (a) are finer than grown grains in Fig.4 (b).
The formation of fine-equiaxed grain consumes distortion energy, reduces dislocation density, loosens stress concentration caused by grain-boundary sliding [5-7], provides new slidable large angle grain boundaries and benefits grain-boundary sliding.

The fine-grained structural material was prepared by rapid solidification process. 15 and 30 percent mixture of fine-grained structural material were added to the base alloy to compare these combinations to the alloy which contained no fine-grained structural material.
The average grain diameter d becomes smaller after the addition of 15 percent fine-grained structural material as shown in Fig. 4 (b).
Generally speaking, a larger number of nuclei can facilitate more nucleation events.
Fig. 7 Size of primary silicon in the HCC Al-18%Si alloy billets with addition of different contents of fine-grained structural material There are a number of advantages of grain refinement such as reducing the degree of porosity and the number of the surface defects.
The grain refiner, metastable colloidal particles, in the liquid phase generally slows the growth velocity of newly formed grains, allowing more grains to thereby nucleate.

Result also shows that the sandblasting process decreases the grain size of the material.
The increment for 85% of UTS is only 7.13% in number of cycles before fatigue fracture shown in this test.
Table 4 shows the final result for number of cycle before and after sandblasting samples.
Number of cycle achieved Before and After Sandblasting Samples Number of Cycle Before SB Number of Cycle After SB Increment 85% UTS 252029 270000 7.13% 75% UTS 338440 1569119 363.63% 65% UTS 518460 4810958 827.94% SEM.
GRAIN SIZE AGAINST SANDBLASTING TIME The reduction trend proves that the grain size decreases if longer sandblasting process is applied on the material.

NA is the sites number of phase A.
NB is the sites number of nano-phase B.
NC is the smaller sites number of that of phase A or nano-phase B. nA is the phase A site number around one specific site of phase A(≤6). nB is the nano-phase B site number around one specific site of nano-phase B(≤6). nC is the nano-phase B site number around one specific site of phase A when NC is the phase A site number(≤6), otherwise, nC is the phase A site number around one specific site of nano-phase B when NC is the nano-phase B site number(≤6), nD is the pore phase site number around one specific site of phase A(≤6), nE is the pore phase site number around one specific site of phase B(≤6). δQiQj is the Kronecker delta function.
The number ratio of intra/intergranular nano-particles Grain growth and Densification.
With densification, the pinning effect of pores on grain growth is gradually weak because of the reduction of pores number, especially after 300 MCS, and grain growth is enhanced rapidly.

With shear stress increasing, a large number of dislocations, twins, and other defects are formed in the crystal lattice, and the lattice distortion can also increase.
At the same time, due to the formation of nano-crystals, there have been more grain boundary and sub-grain boundary.
As the rotate rate increases, the powder size decreases gradually, meanwhile, the uniformity of particle distribution is improved and the number of aggregated powder decreases.
After the powders absorb the energy of impact, they break and a large number of small particles are generated.
Acknowledgements The financial support provided by the key program for Heilongjiang province Natural Science Foundation (contract number: ZJC 0604) and"973"program of China (Project NO.: 2008CB617604) is gratefully acknowledged.

In consideration of the number of filler materials currently available, it is necessary to be able to sort these components well and use them optimally.
The results of the larger magnification of specimen 1 were misrepresented, as there is also a very large number of small particles in the specimen.
In contrary, the last specimen (number 6) with the smallest grains has a larger magnification (149 x 149 μm area).
An important aspect in the measurement is whether the grain volume or the number of grains is considered.
Fig. 4 Size and shape characteristic by grain volume Fig. 5 Size and shape characteristic by number of grain Figures 4 and 5 shows the arithmetic means of the measured values.