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The grain size provides the two significant diamond morphologies of faceted and ballas-like morphologies.
Microcrystalline diamond (MCD) films consist only of faceted diamond grains.
The ultrananocrystalline diamond (UNCD) film is a fine-grained material (3–5 nm average diameter) which consists only of ballas-like grains.
In addition, the top surface of the grains are free from amorphous carbon aggregates, and for samples above 60 vol% Ar, apparently there is a lack of intergranular deposited material as indicated by the large number of flaws between the grains.
In the case of the R=2 only faceted diamond grains was found, whereas, when the R=10 only ballas like grains was found.

The sintered samples (a) and (b), which are synthesized from the calcined powders mixed by hand-milling, have rough microstructures including abnormally grown grains and pores.
The planetary ball-milling could produce fine and uniform powder sources good enough for sintering without anisotropic abnormal grain growth.
This result clearly indicates that the KBa2Nb5O15 grains tend to align their short c-axis in the direction perpendicular to pressing direction by the arrangement of the self-ordered anisotropic grain orientation during uniaxial pressing.
These preferred grain orientations have been observed in other TTB ceramics obtained by hot pressing, hot forging and SPS [3-5].
Therefore, it seems that the parallel-cut sample contains a large number of polar c-axis aligned to the applied electric field, as can be speculated from the XRD analysis.

And finally a thin intergranular layer forming on the grain boundaries will become the weak link of chemical composition and lattice structure[6,7].
Under tensile stress, deformation occur on grain boundaries first(Fig 4).
Once the deformation exceeds the range allowed by the grain boundary, microscopic cracks appear along the grain boundary(Fig5).
Because of aggregation of the impurity phase on the grain boundary, it is very easy to produce low melting point eutectic, which has become a major source of micro crack.
With the increasing of current, welding heat input increases, make the liquid metal in high temperature stage for long time, and this help to promote grain growth, form a bulky structure and a large number of Mg17Al12 or Mg-Zn eutectic phase.

From Figs. 2, it can be seen that the microstructure at different thermomechanical treatments consisted of equiaxed grains, with the microstructure in the final sheet F7 being finer than that in the sheet F9, as shown in Figs. 2.
In ferritic steels, grain size and texture can affect the Snoěk peak height [4,5].
Snoěk peak height has also been thought to be affected by grain size [1,5].
Recently, Saitoh et al. [5] reported that the influence of grain size between 17 and 31µm on the Snoěk peak height is calculated to be less than 4%.
Given that the grain sizes in F9 and F7 final sheets were 20.2 μm and 27.8 μm, respectively, and the variation of Snoěk peak height was measured to be about 40%, the influence of grain size cannot be considered to be the major determinant.

It can be seen in Fig.2 that the substitution of Zr for La brings about the visible grain refinement of the as-cast alloys.
Fig. 4 shows the cycle number dependence of the capacity retaining rates (Sn) of the as-cast and spun alloys.
Fig.6 Evolution of the capacity retaining rates of the as-spun alloys with the cycle number: (a) 10 m/s, (b) 20 m/s Fig.7 Evolution of the capacity retaining rate (S100) of the as-cast and spun alloys with Zr content Fig. 6 describes the evolution of the capacity retaining rates (Sn) of the as-spun alloys with the cycle number.
The increased cycle stability of the as-cast alloys originated from substituting La with Zr is basically attribute to the refined grains and the increased amount of the LaNi5 phase by such substitution.
The anti-pulverization capability of the alloy basically depends on its grain size.

It shows that the grain size decreases with Y content increasing.
But when Y content continues to increase, the grain sizes of the alloys change slightly.
The number and size of precipitates increase and segregate in grains and along boundaries as block morphology when Y content increases to 1.5 wt.%, as shown in Fig.2 (d).朗读 显示对应的拉丁字符的拼音 It has been suspected that the white bright blocks in Fig.2 are phases containing rare earth and the corresponding EDS spectrum analysis presents in Fig.2 (e) and Fig.2 (f).
As shown in Fig.1(a), the grains in Zn-25Al-5Mg-2.5Si alloy are coarse and adding 0.1wt%- 0.8wt% Y, the grains become smaller due to the refining effect of rare earth.
According to this relationship, the smaller the grain size, the higher the strength.

The microstructure of spray-formed AZ80 Mg alloy consists of small equiaxed grains, which are uniformly distributed, with an average grain size of about 30 mm, as shown in Figs. 3 (a) and (b).
The majority of the secondary phases are of very small submicron sizes, which are uniformly distributed within the grains and at the grain boundaries.
For the macrohardness, the effects of the porosity become relatively insignificant as the numbers of grains covered by the HRF and HRS indenters become more and the Hall-Petch strengthening starts to take effect.
The majority of the secondary phases are of very small submicron sizes, uniformly distributed within the grains and at the grain boundaries.
For the macrohardness, the effects of the porosity become relatively insignificant as the numbers of grains covered by the hardness indenters become more, which gives the spray-formed material a higher microhardness than the cast material

Sintering process is influenced by a number of factors, such as sintering temperature, heating rate, sintering time, cooling method and sintering methods, they will directly affect the microstructure of ZnO varistor ceramics, including grain size, grain uniformity and grain boundary structure, thereby affecting its electrical properties, such as voltage gradient, nonlinear coefficient, impact resistance, anti-aging [5, 6].
From Fig. 2, it shows that the sintering time increases from 0.5 h to 5 h, varistor eramic grain grows better, grain size is bigger and more uniform, but the microstructure is still very similar, indicating that there is no new phase, which is consistent with the XRD results in Fig. 1.
Increasing sintering time can make the reaction between various additives, additives and ZnO more sufficient, uniformity between each phase better, and it also helpful for the liquid phase to recrystallize and grain to grow bigger, which makes grain distribution uniformity.
From 0.5 h to 5 h, with the sintering time increases, the varistor ceramic grain grows better, and the grain size is bigger and more uniform.
Chen, Grain growth behavior of Bi2O3-Doped ZnO grains in a multilayer varistor, J.

The grain size as expected [18, 19, 20], grows up with temperature to the two materials studied.
Such behavior is equivalent to the commercial material that obtained average grain size of 0.54 µm at 1500 ° C (Fig. 4b).
The sintering temperature directly influences the grain size, that in turn influence on the mechanical strength, because at higher temperatures the barriers between grain are reduced, they grow together increasing the strength and the number of shear planes, which may lead to fracture of the material [1, 12].
It shows a microstructure of grains with polyhedron forms and non-uniform sizes (Fig.5b).
The increase of temperature (1500 to 1600° C) there is an increase in average grain size.

The weight is similar to the distance, and it enables some control of the size of grains.
The larger the weight is, the bigger is the grain.
The topology parameters, the number of facets per cell and the number of edges per facet and their tessellation characteristics were analyzed.
Three aspects were selected as general descriptions of the composite models: 1) the volume fraction of constituent phases; 2) the mean and standard deviation of the grain volume; 3) the grain volume distribution.
The studied properties included the number of edges, the area and the perimeter per radical polyhedron face, and the number of faces, the surface area and the volume per radical polyhedron.