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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).

Microstructures of the deposits and walls consist of columnar grains and equiaxed grains.
Microstructures of these deposits consist of two types of grains: columnar grains and equiaxed grains.
As the height increases, columnar grains change into equiaxed grains.
Equiaxed grains distribute at the intersection of these inclined columnar grains.
The number of layers containing columnar grains decreases as the laser power increases, and columnar grains turn into equiaxed grains as the height increases for all thin walls.

The results showed that the number of pits in 304L was much more than that in 316L.
Some literatures [5] point out that corrosion occurs in grain boundaries in the first place.
Therefore, the number of grain boundaries will affect the material's corrosion. 3.2 Corrosion Morphology The corrosion morphology of 304L and 316L stainless steel in 85% food grade phosphoric acid after 90 days is showed in Fig.2, It is clear from the micrographs that neither of 316L nor 304L stainless steel has larger and deeper pits, indicating the two steels have higher ability against pitting attack.
However, the surface of 316L resulted in a very low number of pits compared to the surface of 314L.
Conclusions (1) The grain size of 316L is greater than that of 304L and the number of grain boundaries in 316L is more than that in 304L

For development of special thermo-mechanical treatment conditions of low-alloy, low-carbon steels which would provide maximum possible crushing of a structure a detailed information was obtained from previously carried out investigations about the influence of austenitic grain size and degree of this grain fragmentation upon kinetics of phase transformation, type and quantitative characteristics of bainitic-martensitic, ferritic-bainitic and ferritic structures.
For low-carbon ferritic shipbuilding steels it has been determined that final (finishing) plastic deformation of rolled sheets and plates should be carried out close to, and completed a little bit below a point Ar3, what allows for formation of a maximum possible number of ferrite germs on austenitic grains boundaries as well as formation of a developed substructure in ferrite due to its deformation.
Dispersed carbides of MeC type, about 10 nm in size, are evenly distributed over grains body.
a) b) Fig. 3 Fine structure of steel 06Mn"iV"B after special thermol-mechanical treatment: a) granular bainite b) ferrite Investigations have shown, that after plastic deformation of unrecrystallized austenite at temperature lower than recrystallized austenite temperature, number of dislocation boundaries in granular bainite increases, ά-phase areas are broken into misoriented fragments.
Formation of ultra- fine-grained and submicrocrystalline structures is provided by carrying out control over size of grains and subgrains in the course of technological processing, as well as over correlation and morphology of structural components at stages of heating up before rolling or heat treatment, at plastic deformation and in the process of phase transformation at cooling. 2.

Image analysis techniques which can discern individual `grains' (the circular Hough transform and the ImageJ particle analyser) were used to evaluate the grain size distribution from SEM images.
(a) ImageJ analysis: grain outlines (b) ImageJ analysis grain size distribution Fig. 6: CuO thin film crystallite size analysis using ImageJ.
A number of image analysis techniques can be used to extract size distributions from high resolution SEM images.
It is surprising to observe thermal activation behaviour in such a highly disordered film, comprising a large number of grain boundaries.
This result is perhaps surprising given the extremely large number of grain boundaries and associated defects that are found within our sample.

The film thickness was varied by depositing different number of layers.
Fig. 1: Average WO3 film thickness as a function of number of spin-coated layers.
As a result, the number of oxygen vacancies decreases[14] and transmittance are increased.
It was explained that the grain boundaries caused the light to spread.
This shift is associated to the compressive stress due to the lateral grain growth caused by neighbouring grains, after which outward growth normal to the deposition substrate occurs.

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.

For the extrusion speed of 0.2mm/s, the microstructure of extruded Mg rods was composed of equiaxed fine dynamical recrystallized (DRXed) grains and some elongated coarse un-DRXed grains.
On the one hand, higher extrusion speed not only enhances the nucleation of DRX grains but also shortens grain growth time and thus benefits to grain refinement [14,19].
The repeated number of the tensile testing specimens for every extrusion speed was three.
When the extrusion speed was increased to 4.0mm/s, as shown in Fig.1(c) and (f), the DRXed grains in the extruded high-purity Mg rod were remarkably coarsened and the elongated coarse un-DRXed grains vanished.
The following main conclusions can be drawn: (1) The microstructure of high-purity Mg rods extruded with extrusion speed of 0.2mm/s composed of equiaxed fine DRXed grains and some elongated coarse un-DRXed grains.

Also, the effect of holding time on the cavity damage was examined with the number of cavities.
Both number and size increased with increased holding time.
Relationship between cavity number and size with various holding times.
As is shown in Fig. 8, cavities were observed along the prior austenite grain boundaries, and the intergranular damage is believed to be caused by these cavities.
Cavity of crack growth path and cavity at grain boundary with various holding times.

On the other hand, the number of under-3um Al-Fe-Si particles at outside surface was much than that at inside.
The number of over-3um and low-aspect- ratio particles was almost same.
Black lines are large angle grain boundaries >15°.
Cube grains were observed under small cracking area.
Black lines are large angle grain boundaries >15°.