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As a novel grain refinement technology, ultrasonic vibration can significantly refine grains and improve properties of alloy with the interaction of cavitation and acoustic streaming effects caused by periodic alternating sound field applied on the melt during the ultrasonic vibration [4, 5].
Along with the increase of silicon content, the numbers of the triangle plate shaped primary silicon and the short needle-like eutectic silicon ascends.
This is due to a large number of gas nuclei cavitation bubbles, which are compressed and stretched under the alternating positive and negative pressure generated from ultrasonic wave’s longitudinal propagation in the melt.
However, when the silicon content is too large, the matrix will be excessively cut and the bonding strength between the silicon grain and the matrix decreases, which means the silicon grain will be removed more easily by the shear stress, and as a result, the increase of silicon will aggravate the wear of the matrix [7].
So due to the ultrasonic waves, a large number of nucleation particles are generated in the melt and the silicon in the melt can precipitate sufficiently.

Under the test condition, the emission of formaldehyde of the self-adsorption fiber board added with 10% activated carbon grain can be reduced by 35%.
Table 1 Technical Index of Activated Carbon Form Grain size ASTM mesh Specific surface area [m 2/g ]Min Methylene blue adsorption （carbon tetrachloride absorption rate % Min） [mg/g]Min Iodine number [mg/g]Min Ash content [%] Max Powder 200～325 1000 180 1000 15 Grain Diameter 1.5 1000 （70） 1050 12 The adhesive is made in the laboratory and the technical index list in Table 2.
Moreover, the reinforcing effect of grain activated carbon is better than that of the powder activated carbon.
However, the uneven distribution of activated carbon grains in the panel leads to a poor mechanical performance evenness of the panel.
In the test, the density of the self-adsorption fiber board added with 10% grain is higher than other specimens, but its water absorption thickness expansion rate is only 9.7%.

However, it will generate coarse and uneven particles because a large number of groups attached to the surface of agglomerate and then begin to nucleate and grow quickly.
With the temperature further increasing (T=180℃), the grain begin to gather and grow up.
So it will has little effect on grain refinement by prolonging the reaction time, one the contrary, it would make the grains continue to grow.
In Table 1, d is the grain size after correction.
The smallest grain size of SrTiO3 powder is about 60nm.

Temperature-dependent grain size for the zirconia ceramics [12].
It is known that the strength of materials strongly depends on their grain size.
The grain size of Y-TZP influences also its degradation behaviour.
Present investigations also confirmed the grain size dependent phase stability.
Kurzydłowski: Advances in Materials Science 2007, vol. 7, number 2 (12) 76-85

Remelting among grain boundaries leads to the deterioration of performance rapidly.
Grainy copper-rich ε phase was uniformly distributed among grains.
The copper-rich ε phase, as a hard and brittle phase, distributed between grains with discontinuous reticular structure will cause stress concentration among grains as a result of different deformation rates of matrix and ε phase.
It is indicated that over burning happened in grain boundary, the narrow black regions along grain boundaries as shown in Fig. 6 (h), while the temperature of solution treatment was 380oC.
Meanwhile, re-melting happened among grain boundaries cause deterioration of performance rapidly.

In addition, a decreased percentage of WC angular grains and an increased portion of cubic/rounded grains can be seen.
The triangle indents located at the grain boundaries and inside the grains refer to the Berkovich indents developed upon examining the sample by nanoindentation.
Figure 6: a) Optical micrograph showing the number of microhardness tests on the cross-section of the consolidated sample; b) contact depth vs. nanohardness-Young’s modulus plot A wear test was applied on the final sample to test the wear resistance of the model using the pin-on-disk approach.
This consolidation did not lead to significant grain growth in the WC grains maintained in the nanocrystalline structure.
Sakaguchi, Properties of ultra-fine grain binderless cemented carbide ‘RCCFN’, Int.

In particular, due to the significant increase in the number of automobiles, numerous cracks above the estimated numbers has been observed in the bridges of motorways.
Therefore, shot peening has been conventionally used as a method to reduce fatigue cracks, because the compressive residual stress can be obtained by the surface’s deformation generated by the high-speed impact of shot grain.
Because the shot peening treatment involves the combinations of many factors in the collision between shot grains and the specimen’s characteristics, and the mechanism of micro-structural transformation is also important point to consider the process’s effect.
In addition, shot grains possibly remains on the specimen surface, and the contamination of shot grains might deteriorate the functionality of metal surface [4].
Therefore, there is no risk in residue of shot grains because no shot material is required.

Al-Cu alloys bar with the mean grain size of 200 µm was fabricated by melt extrusion; however, the mechanical properties have nothing to do with the extrusion ratio.
Introduction Compared with conventional diecasting routes, semisolid materials (SSM) processing has a number of advantages, such as low porosity, heat treatability, consistency and soundness of mechanical properties, the ability to make complex component shapes and longer die life [1,2].
The coarse grains (grain size of 300 ~ 400 µm) and the fine grains (grain size of up to 100 µm) are distributed uniformly, and an equiaxed structure with the mean grain size of up to 200 µm was formed in the melt extruded bar.
Al-Cu alloys bar with the mean grain size of 200 µm was fabricated by melt extrusion process.

The improved ferroelectric and leakage current characteristics can be ascribed to the plate-like grains of the BLT films.
BLT consisted of well-developed plate-like grains with considerable volume fractions of micro grains.
The grain size is close to 65 nm and. roughness is about 7.5 nm.
The domain walls in plate-like grains are easier to be switched under external field.
Lanthanum substitution reduces the number of defect complexes that act as space charge in the pseudo-perovskite layer.

The matrix, gray Al2O3 grains, show regular grain size, straight grain boundary, tight integration with each other, no obvious defects and pores.
White ZrO2 with small grain size is dispersed on Al2O3 matrix grain boundaries and small amount of fine ZrO2 grains were distributed in Al2O3 grains, forming a typical in-grain and grain boundary structure the crystal, which can be seen from TEM micrographs, as shown in Figure 3.
Studies in references [7-8] show: the structure of the composites includes not only the matrix primary grain boundary, but also the grain boundaries of nano-ZrO2 and micron grain of the matrix, as well as a large number of micro-cracks, due to ZrO2 in matrix grains; ZrO2 grains in Al2O3 grains and on Al2O3 grain boundaries produce large amounts of dislocations in ceramic matrix.
Although both ZrO2 grains within matrix grains and on matrix grain boundaries can form the grain boundaries between ZrO2 and Al2O3, two types of grain boundaries will have the different contributions to the mechanical properties of the composites.
Most ZrO2 grains uniformly distribute in the alumina grain boundaries and a small amount of ZrO2 grains with small grain size present in Al2O3 grains, forming a typical intra / inter-hybrid nanocomposite ceramics