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A number of grain refining additives have been discussed such as Ca, Sr [14, 15, 16] or even Mn [17].
Small pinning particles of stable intermetallic compounds could be used as grain stabilizers preventing further grain growth to a certain extent.
However, the application of forged parts based on magnesium is restricted to a small number only [4, 25].
Fig. 11 shows two flow-curves at 350°C of the materials in the DC-cast condition, one is coarse-grained with an average grain size of 400 µm, the other is fine-grained with 80 µm on the average.
Fig. 12: Conventional coarse grained sample (left) and fine grained sample (right) after deformation.

Thermal neutrons and high energy X-rays both have a high penetration power for a large number of materials [5].
A subsequent annealing leads to a coarse grained microstructure.
One can see clearly some single grains, which indicates an insufficient number of grains for a texture analysis using the volume method even for a bundle of 10 parallel wire sections.
In figure 4b one can see a much better grain statistics.
Nevertheless the number of grains was still to low for a sufficient result.

On the other hand, the PV sample with 35μm of grain size showed a higher breakdown voltage compared to that of the conventional alumina with the same grain size.
Table 1 Grain size and fracture toughness of the dense alumina materials Figure 4 shows change of thermal conductivity of the alumina samples with grain size.
While the number of grain boundaries of the conventional alumina with grain size 10μm was 380 units/mm, the number of boundaries of the PV and PP samples decreased to 92 and 39 units/mm, respectively.
This reason was thought that the PV sample had higher mechanical properties, but grain size was not so small: 12μm, as shown in Fig.4 and the number of grain boundary was not so large: 92 unit/mm.
Furthermore, the grain boundary between anisotropic grains with match lattice plane seemed not to have a high barrier of the heat conduction.

AFM studies indicate that the grain size and surface roughness increase with the film thickness.
This is mainly due to the increase in average sizes of grains caused by the increase of film thickness coming from the increasing number of laser pulses.
Average diameter of grains and surface roughness of CdS thin films CdS thin films Avg.
This means that as the number of laser pulses increases the bandgap reduce.
AFM images indicate that the microstructure of the films surface consist of spherical shaped grains.

It has been well aware that two important strength-reducing characteristics are knots and slope of grain along the lumber.
The upper one is failed due to large knots, and the lower one is due to high slope of grain.
The SOG scanner measures the average slope of grain over the width of the lumber.
In each figure, the knot indicator and the slope of grain are plotted from the results of the 2 corresponding scanners.
It can be seen that grading with the SpeedGrader reduces the number of low-grade lumber and increases the number of high-grade lumber.

Fig 1 illustrates that the grain size increases with elevating the deposition temperature.
It indicates that the GBs of above-mentioned samples contain a large number of amorphous phases (a-phases).
By the above analysis of SEM and XRD, it is considered that there are large numbers of a-phases at GBs.
Fig. 2 XRD patterns of polysilicon nanofilms with different deposition temperatures Fig. 3 Interstitial-vacancy model of amorphous phase at grain boundaries In our model, each IV pair can be characterized by the number of neighboring IV pairs (defined as IV pair coordination number).
An IV pair can recombine after capturing enough energy, and the recombination rate increases as the number of neighboring IV pairs (the coordination number) decreases.

The development of extremely sharp cube texture in the 8 cycle processed material could be attributed to the oriented nucleation of cube grains at early stages of recrystallization and subsequent growth of these grains.
Fig.1(a) is the grain boundary (GB) map in which the high angle grain boundaries (HAGBs with misorientation angle θ>15°) and low angle grain boundaries (LAGBs with 2°≤θ≤15°) have been highlighted in black and light grey lines, respectively.
Presence of significant number of off-cube oriented grains could be easily observed in the microstructure in this condition.
Oriented nucleation of cube grains plays a significant role in the formation of the sharp cube texture.
Legoues, Orientation Dependence of Grain-Boundary Critical Currents in YBa2Cu3O7-δ Bicrystals.

One calibration block was varied the grain size by annealing process.
The macrostructure, microstructure, grain size and grain orientation of weldment were analized by microscope.
The large grain size has high attenuation because of beam skewing and scattering at grain boundary [4].
From the microstructures of base material and annealing SDH block found that the grain sizes were number 9.5 (13.3 µm) and 5.0 (63.5 µm).
The grain size number of HAZ was 8.0 (22.5µm) that larger than grain size of base material.

Some cladding tubes were annealed at 700oC for 3 hrs to induce the grain growth.
In the annealed Zr-Nb-Sn-Fe alloy cladding tubes, dislocation-free recrystallized grains with a larger grain size were observed.
However, other studies have indicated that the creep rate may increase or decrease with decreasing grain size, or be grain size-insensitive in copper6.
Both models suggest that the effect of grain size varies with experimental temperature and conditions even in identical materials and the dislocation activity near-grain-boundary regions could increase the creep rate in the small grain size region, supporting the decrease of creep rate with increase of grain size in the present study.
In general, with the increase of temperature, the number and mobility of thermal vacancies increase, causing more vacancies or impurities to diffuse to grain boundaries.

The microstructure with coarse carbides and large grains reached greater loss of impact toughness [9].
The number of particles per µm2 was calculated by counting the precipitates and their diameter was directly measured.
The fractographic analysis revealed the presence of two types of particles precipitated within the fracture surface [11], which were intergranular, i.e., along the grain boundaries, and transgranular across the grains.
Substitute pin showed a larger transgranular particle density value compared to that of the original pin, which was related to a greater number of particles precipitated.
The original pin showed medium size, nearly rounded particles (Fig. 6a), which exhibited preferential transgranular precipitation, i.e., across the grains, followed by the intergranular precipitation (among grain boundaries).