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Table 1 Chemical composition of RE metal (mass fraction, %) RE (Ce) (La) Fe Si P S 99.10 49.71 49.39 0.31 0.028 0.005 0.0045 Table 2 Chemical composition of heavy rail steel (mass fraction, %) Number C Si Mn Cr V Total.
Firstly, the interfacial energy of grain boundaries is decreased and the structure of grain boundaries is changed because RE atoms tend to segregate preferentially on the grain boundaries.
Furthermore, RE atoms can hinder the diffusion paths of carbon atoms because RE atoms tend to segregate in the defect positions, such as grain boundaries, dislocations, sub-boundaries and so on, which are the optimum diffusion paths for carbon atoms.
RE atoms tend to segregate on the grain boundaries, thus the interfacial energy of grain boundaries and the heat activation condition are decreased, and the shear strength of austenite and the resistance of martensite transformation are improved, so the starting temperature of martensite transformation is decreased by RE.

A number of experimental and theoretical treatments have shown that the occurrence of recovery simultaneously with recrystallization has the effect of reducing the recrystallization rate [1, 2].
Table 1 Bulk Composition [wt%] Fe in solution [wt%] Grain Size A Al-2.5%Mg-0.002% Fe. 0.002% ~ 100µm.
Composition and initial grain-size of the alloys used in this investigation The samples were cold-rolled to an equivalent von mises strain of 1.
Metallographic observations indicate that grain-boundaries are the dominant nucleation sites in alloys A and B (Figure 2-a).
In alloy C, the Fe intermetallics play an important role during nucleation (Figure 2-b), particularly, when they are present at the grain-boundaries.

The roughness seems to increase with a oxygen pressure; at the same time, the grain size on the surface also varies.
For the film grown at a low oxygen pressure (5 mTorr), the grain size is around 60.09 nm and seems relatively constant.
On the contrary, the film grown at a higher oxygen pressure (10 mTorr) has the grain size of around 94.18 nm and the roughness of the film rapidly increases to about 7.349 nm.
The initial decrease in resistivity with increase in oxygen pressure can be attributed to an increase in the grain size of the AZO film from 34.12 to 94.18 nm, thus reducing the grain boundary scattering and increasing the conductivity.
Since electrons in the AZO films are supplied from oxygen vacancies and aluminum atoms in the film, it can be though that an increase in oxygen content might cause a decrease in the number of oxygen vacancies, resulting in an increase of resistivity.

The grinding process was carried out using SiC sandpaper (grain size 600, 1000, 1200 and 1500) on rotary sander.
The lower porosity at sample top in comparison to the base ones is due to higher particles number at this location into the samples.
It can be due to starch grains and alumina base "suction" caused by gypsum mould and the gravity effect.
On the other hand, at the sample top there is more starch grains gelling due the presence of water responsible for the increasing of the grains size.
The alumina grains that contributed to increase porous values are smaller.

In many ways, the process of cavity sintering can be viewed as the opposite of growth, with vacancies diffusing from the cavity along grain boundaries [1].
Little is known regarding the minimum stable size of a creep cavity during sintering, although as a first approximation it can be assumed to be the same as for nucleation where the stable radius r is given by [7-9]: r=2γσn (2) where σn = local normal grain boundary tensile stress.
Using this relationship does assume that the cavity surface energy remains constant for the duration of the cavities existence, when in reality it may be modified by the preferential segregation of impurity elements to grain boundaries and/or the internal surface of a cavity [7,10,11].
Secondary phases can effect creep damage accumulation in a variety of ways depending on type, size, distribution and number density [7,12-17].
The cavities in the ex-service and subsequently heat treated sample have an equivalent diameter in the size range of 0.2-3.1 µm dia., with a mean size of 0.5 μm dia.. 3D tomography and subsequent reconstruction show that 85% were lenticular, with the major axes along the grain boundary.

Only about 10% of the crop parameters need to be debugged according to the specific test results, mainly including growth rate, partition coefficient of dry matter, specific leaf area, relative growth rate of leaf, death rate of leaf, transfer coefficient of stem photosynthate and weight grain of maximum.
(1) (2) Note: n is the sample number of observed value, Yi and Xi are simulated value and observed value separately.
Only about 10% of the crop parameters whose response to the environmental characteristics is the most important need to be obtained by the experiment, among them, growth rate is obtained by the DRATE, distribution coefficient of dry matter and specific leaf area such kind of characteristic parameters of crop growth are obtained by the PARAM subroutine, The biggest single grain valley is obtained by the grain weight data from yields.
Among them, Growth rate, specific leaf area, photosynthate distribution coefficien and the biggest single grain valley can be seen in table 1.
Table 1 Main parameters of ORYZA2000 model calibration growth rate specific leaf area partition coefficient of dry matter weight grain of maximum development stage DVS development stage SLA development stage leaf stem sheath Grain kg 0～0.4 0.000462 0.00 0.0040 0 0.5 0.5 0 0.0000274 0.4～0.65 0.000758 0.16 0.0040 0.5 0.5 0.5 0 0.65～1.0 0.001386 0.33 0.0030 0.75 0.4 0.6 0 1.0～2.0 0.001368 0.50 0.0028 1 0 0.4 0.6 0.65 0.0025 1.3 0 0 1 1.50 0.0024 1.5 0 0 1 2.10 0.0020 2.5 0 0 1 2.50 0.0020 Model simulated results Fig. 1 comparison of simulated and observed dry matter, yield and Leaf area index of rice from ORYZA2000.

The Vickers microhardness tests were performed in a Shimadzu HMV-G microdurometer, in the numbered regions of Figure 3, using 200 kgf as a load, and following the NBR-6672 standard.
Equiaxial grains can be verified throughout a microstructure formed by fine precipitates and nonmetallic inclusions in a continuous matrix.
The grains in both samples were highly deformed, and deformation bands could be observed inside the grains.
Therefore, even in the PC-SD sample, grains highly deformed can be noticed.
It is observed the elongation of the grains following the rolling direction, which is the result of the original mechanical treatment H34.

The ceramic ZrO2 having grain size of 40µm was fed into the feeder of ASP machine.
Thus, the grain size gets refined.
The effect of grain refinement is reflected in terms of increase in hardness and wear resistance.
This is attributed to the fact that ZrO2 is a hard phase and also refinement of grain size while freezing on the surface during plasma spray.
The grain refinement of the ZrO2 due to rapid freezing during coating adds to the hardness which in-turn increases the wear resistance of the coating.

Using the mechanical, ultrasonic, and electromagnetic vibrations during solidification may have the advantage of promoting grain refinement of the composite, by reducing the shrinkage porosities, with an increased density [4].
The introduction of high intensity ultrasonic vibration into the melt may control the columnar dendrite structure, reduce the size of equiaxed grains, and under some conditions, produce globular non-dendrite grains [5].
The application of the mechanic, sonic, and ultrasonic vibrations has a number of notable effects such as grain refinement, increased density, reduced shrinkage, and on the shape, size, and distribution of the second phase [7, 8].
Vertical vibration is the most commonly used vibration mode, because it strongly influences on the growing grains [9].
The fracture surface of the grain refined composite showed broken Aluminium and TiC particles (Fig. 4) and well-attached particles within the dimples, indicating rather good interface cohesion between matrixes and reinforcing particles.

Users specify the turntable speed, the load, and any other desired test variables such as friction limit and number of rotations.
In addition, grain boundary strengthening is also expected because the TiB2 can act as a grain refiner in Al-Cu alloys.
An increase in volume fraction of TiB2 particles reduces the grain size of the cast alloy from 115 to ~ 40 μm.
%Cu with 6%wt TiB2 more fine grain and quite smoothly compare to 3%wt of TiB2 and without TiB2 (0%wt.).
Coarse grain or surface roughness can be observed in micrograph of Al-Cu matrix as shown in Fig. 5(a).