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The average grain size in the streaked region is about 50 µm, while the grain size away from the streak is 80 µm.
For example, if there is locally a high density of intermetallic particles in the extruded surface, a large number of etching pits would be produced which will influence the appearance of the surface after anodising.
However, if grain boundary attack is pronounced, the grain boundary grooves may become a major surface defect.
The reflectivity of the surface is reduced by the presence of a smaller grain size and deeper grain boundary grooves.
Therefore, a small grain size band may result in a dull streak.

It can be seen that the microstructure under different solution temperatures are of equiaxed grain structure, and that the grain sizes increases with increasing solution temperatures.
The grain boundary mobility increases with increasing temperatures, which resulted in the increasing grain sizes with increasing solution temperatures for this metal matrix composites.
It can be seen that the microstructure under different solution temperatures are of equiaxed grain of different sizes, and that the grain sizes increases with increasing solution temperatures.
The formation of refined grain sizes should be due to higher energy storage caused by more severe deformation, which is benefit for the forming of more nucleus and more refined recrystallized grains.
Acknowledgement It is a project supported by natural science foundation of shanxi province China (project number: 2011011021-1).

Microstructure of wires fabricated usin 800 rpm consists finer equiaxed mg grains with finer precipitates homogeneously distributed along the grain boundaries.
To fabricate the magnesium based components, machining is main process and as the number of applications increasing with the use of magnesiumm, the scrap volume is also increasing.
It consists of approximately equiaxed grains of 100 µm with the grain boundaries discontinuously covered by the precipitates.
The microstructure consists of larger grains surrounded by finer grains with precipitates at their grain boundaries.
The average grain size at higher rotational speeds is 180 µm which is much higher than the as cast base metal grain size.

Different annealing times at 850°C were applied to create different number densities and sizes of the NbC-precipitates in order to study the effect of NbC precipitation on the transformation kinetics.
The ferrite grain size is measured by means of optical microscopy.
A smaller grain size is known to lead to advantageous material properties such as high strength.
In the austenite-to-ferrite transformation the α/γ-grain-boundary mobility influences the rate of grain growth and as a result it also influences the evolution of the ferrite fraction.
At the cooling rate of 10 °C/min, the microstructure consisted of larger grains.

Figure 4 shows the changes of Fx, Fy and Fz with sliced line number.
Fx shows almost no change with line number.
type is non-active diamond grains with little protrusion, and the third is dropped diamond grains.
speed and number of sliced lines. 4.
At a high wire speed, the normal force, the number of active diamond grains and the workpiece surface roughness were reduced.

The ferrite matrix is homogeneous with an average grain size of ~0.3 micrometers.
In principal, the plastic deformation capability of a material is direct proportion to the number of active slip systems.
The investigation shows that at least five independent slip systems must be operative simultaneously in a grain to avoid the cracking.
Thus the additional slip systems of（110）[111]and（011）[111]become active and then the cementite possesses a sufficient number of slip systems for plastic deformation.
The microstructure after three passes of ECAP is shown in figure 3(b) with clear extinction contours along grain boundaries.

A fine-grained granitic rock is utilized to study the effect of dynamic strain rates on failure response theoretically.
The rock selected for this investigation is a fine-grained granitic rock, known as Laurentian granite.
The rock appears homogeneous with red and light mineral bands and presents a fine-grained texture.
Damage parameter D can be derived by a function of number of active flaws (Walsh, 1965) based on the Weibull distribution of flaws and then damage rate is given by (2) where l is the radius of flaw, m and k are constants of dynamic material property, is volumetric strain and , n is number of flaws which can activate at or below a strain level of and n is formulated by .
Approximately, 23% of grains have an average length of 0.72mm, 51% of grains have an average length of 0.59mm.

When the proportion of tungsten powder rose to 10%, there was reticular secondary carbide precipitating along the grain boundary.
The dendritic crystal grain was composed of higher melting point metal, such as W and Cr.
The crystal grain in transition zone was much bigger because it had longer growing time.
Acknowledgements This paper was supported by the science and technology project of Zhejiang Machinery and Electrical Group Limited Company (project number, 2014JD001).
Besides, the author would like to appreciate the financial support from the scientific research sustentation fund from Zhejiang Provincial Education Department (project number, Y201328309) and Sliding Bearing Engineering Technology Research Center of Zhejiang Province (project number, 2012E10028).

The YAG:Ce used as the conversion material, in its coarse-grained form, is a well known, intensely studied phosphor.
X-ray diffraction (XRD) was used to examine the structure and grain size of the material.
Excitation spectra for emission at 530 nm of nano-YAG:Ce with xCe = 0.25 at.% and the coarse-grained reference.
This can be caused by a reduced number of possible transitions between different vibrational wave functions of the ground state and the excited state of the Ce 3+ ion (configuration coordinate model [5]).
The number of active luminescence centres in the host lattice increases, thus, more photons of the 450 nm exciting radiation can be absorbed and converted.

The results show that the corrosion rate of the ultrafine-grained alloy increases, in comparison with the coarse-grained alloy.
The number of ECAP passes is 4.
For the as-cast alloy, the average grain size is about 100 mm.
With multipass ECAP, remarkable grain refinement occurs by repeated shear deformation, and the grains were refined to submicron level after four passes.
(1) The corrosion rate of the ultrafine-grained alloy increases in 3.5% NaCl solution, in comparison with the coarse-grained alloy.