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Therefore, a large number of Nb-based complex perovskite materials have been reported in the scientific literature because Nb2O5 is comparatively cheap.
The grain size of 0.25wt% V2O5 doped BMN ceramics at 1350 o C is similar to the pure BMN ceramics at 1500 o C.
The dielectric loss, which was cause by the grain boundary, will be lower with the grain size increasing and the grain boundary decreasing.
But too large grain size will increase the probability of new defects such as dislocations.
Due to the second phase and the irregular grain morphology, the sample of 0.5 wt% V2O5 addition had high relative density, but got low Q value which is very important for the applications of microwave dielectric ceramics.

After rolling wire in the water cooling section by adjusting the water box opening number, pressure, and nozzle ring joint parameter so that the fine and uniform austenite grain.
The main factors and the following effect: (1) Effect of heating temperature The heating process and heating quality of different decisions on the subsequent deformation temperature, finishing rolling entrance and final rolling temperature, and initial austenite grain size and the determinants of high carbon steel, ordinary (non microalloyed) at 1323K reheating temperature, there exists the abnormal grain growth of the original austenite, and with the heating the increase of temperature, decarburization tendency also significantly increased
(2) Effect of finishing rolling temperature on properties The control of final rolling temperature is the main control of austenite grain size, generally finishing rolling temperature, grain size.
The strength and toughness of high carbon steel is more strict requirements, due to the use of property and processing property of them require fine grain, so the final rolling temperature can not be too high, general control in 1203~1253K
Water cooling speed plays a decisive role on the growth of austenite grain and the influence of the microstructure after phase transformation.

Strengthening mechanism is mainly in solid solution strengthening, fine grain strengthening and the excess phase strengthening.
Aluminum as the main alloy elements can refine grain, with zinc to form a solid solution strengthening effect, while maintaining high temperature super plasticity, improve the alloy casting fluidity.
Determination of copper content in alloy Based on the analysis of alloy elements, and a large number of domestic and foreign literatures, the ingredients were identified as table 1 The of experiment Changing cooling On the basis of ZnAl14Cu10, this experiment adopts air cooling, water cooling, oil cooling, cooling in the furnace methods.
(a) (b) (c) (d) Fig.5 Microstructures of sample (a) Air cooling; (b) Water cooling; (c) Oil cooling; (d) Furnace cooling Analysis and discussion By the graph 2, 3, 4 can be judged, different methods of cooling the microstructure grain sizes are different, the oil cold grain was significantly smaller than the other cooling way of obtaining grain structure, and the oil cooling way of the organization more fine and uniform.

Microstructural analysis showed the differences in the grains sizes of metal welded zone and heat affected zone.
However, along with a significant number of advantages, this welding method has a number of important disadvantages.
The metal of the rail (Figure 4, c) has a coarse-grained structure, which indicates that this area adjacent to the welding zone was overheated and large austenite grains led to the formation of a plate pearlite with a ferrite grid.
Areas of overheating in welded joints are dangerous, since the reduced-plasticity and toughness are characteristic of the coarse-grained structure of the metal.
As a result of the thermal action on the welded rails near the border of the weld metal and the rail fusion, a region with a coarse-grained structure and an increased hardness of the metal is formed, which is characterized by reduced plasticity and toughness.

The effects of deformation temperature T and strain rate can be combined as the number of thermally activated events per unit strain, which can be expressed in the Zener–Hollomon parameter, Z, as shown in Eq. 1
At 730°C the elongated grains and the thick grain boundaries were observed, as shown in Fig. 5 (d)(e) and (f).
The previous study has indicated that boron in the form of Fe2B segregates along the grain boundaries in the Fe-Ga alloys, leading to the thick grain boundaries.
For the sample tested at 900°C with strain rate of 0.1s-1, inset within the scan is a close-up of the local, a large number of sub-grains in the grains is observed (Fig 5 (g)), which demonstrates that the dynamic recovery occurred under this deformation condition.
At 900°C fine DRX grains are observed along some grain at higher strain rate (1.0 and 10 s-1), as shown in Fig.5 (h) and (i).

Its mineral grain size is finer, among of which less than 45μm size accounts for 51.49% of the total, and the content of less than 20μm size is 20.85%.
The grain size statistical results of sphalerite, galenite and pyrite are shown in Table 5.
The grain size statistical results show that the concentrating is more difficult, for the grain size of main metallic minerals in the ore is very fine, and the mineral dissemination is complex, so only deep and fine grinding is able to make fully minerals dissociated.
Table 5 Grain size statistical results of dominant metallic minerals (%) Grain Size (μm) ＞100 100~60 60~45 45~20 20~10 ＜10 Total Sphalerite 17.70 10.40 6.30 31.30 26.70 8.30 100.00 Galenite 30.61 10.51 7.39 30.64 17.55 3.30 100.00 Pyrite 29.90 10.20 12.33 28.17 15.90 3.50 100.00 Experiment research on mineral processing 3.1.
The concentrating is more difficult, for the grain size of main metallic minerals in the ore is very fine, and the mineral dissemination is complex. 2.

The parallel with grain boundary diffusion.
There is an interesting parallel between dislocation and grain boundary diffusion.
Interstitials are as important in grain boundaries as vacancies.
In fact, such collective mechanisms dominate in most grain boundaries, which makes grain boundary diffusion similar to diffusion metallic glasses.
The goal of this step is to obtain a small enough number of dynamic atoms that permits long MD runs.

Polygonal grains and reticulated Mg5(Gd,Y) eutectic phase at the grain boundaries are presented in the as-cast microstructure as shown in Fig. 1a.
After homogenization treatment, the average grain size of the as-homogenized sample is about 110μm, the phases along grain boundaries have been completely dissolved, only small number of block particles randomly distributed in the grain interior, as shown in Fig. 1b.
However, no remarkable traces of the formation of new grains by dynamical recrystallization can be found.
However, it was suggested that the grain boundaries be weak as compared with precipitation-hardened matrix [8, 10].
Conclusions (1) By rolling with 5% reduction per pass in GWK930, the number of the twins increased with the accumulative rolling reduction, the grains were refined via division by twins and recrystallization.

Scanning electron microscopy analysis of sandstone shows when magnified 1000 times there are visible microcracks about 10~50 μm; when magnified 2500 times there can be observed microcracks and grain dissolution hole.
Can be seen from the above analysis, B10 coal’s microcracks are more developed and has good connectivity, wide crack, and particle surface erosion is serious, and there are a large number of dissolution holes.
They have good connectivity and filling with strongly swelling sheet I/S mixed layer mineral among grains.
Compared with coal and sandstone, the microscopic structure of mudstone is relatively better, the number of microcracks and pores is relatively few, and the width of the crack is smaller.
Microcracks and pores are developed and have good connectivity and grain table is seriously corrosion

Table 1 Serial number and compositions of the SnO2 samples Sample No.
With 0.1 mol% Sb2O3 doped in the SnO2+0.5%CuO ceramic, the grain size undergoes a fast growing during the sintering process (Fig.2b): the high grain boundary mobility entraps small-diameter pores within the grains and at grain boundary.
However, when Sb2O3 increases to 0.5 mol%, the grain size is smaller and the relative density is higher (Fig.2c and Fig.1).
When the amount of Sb2O3 reaches 1.0 mol%, a large number of through pores are found at grain boundary (Fig.2d).