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Yongxin Sun et al[4] also put forward the theory of dissolution-crystallization in preparing the ZrO2 grain by microwave hydrothermal.
Lastly, if the solution is in microwave with high frequency electric field, it would make a large number of ions collide, which produced a large amount of kinetic energy providing energy for reaction.
Spherical crystal has more narrow grain distribution(3~5nm).
The average grain size is 8.5nm and the crystal is single-phase.
With increasing temperature and reaction time, the grain size increased and lattice parameters reduced, and γ-AlOOH with high thermal stability was obtained.

Skutterudites form covalent structures with low coordination numbers for the constituent atoms and so can incorporate atoms in the void [1].
However, the regular shape and size of grains were ontained by annealing as shown in the HPA specimen.
The hardness of the AM specimen was 275 Hv, which is a little lower value for binary CoSb3 because it has large amount of unreacted Sb elements and large grain size.
The hardness increased to 340 Hv (HP) by the hot pressing due to its smaller grain size and phase change to CoSb3.
However, it decreased to 280 Hv (HPA) by annealing due to the grain growth and stress release. 40�40�40� (a) (b) (c) Figure 1.

It includes controlling of parameters such as grain size, porosity and its distribution, morphology of metallic and non-metallic secondary phases available in microstructures, macro and micro segregations and etc. [5, 6].
The main effect of vibration during solidification on the microstructural of metal and alloy is the suppression of columnar growth and formation of small equiaxed grains [7, 8].
However, a review of the literature reveals that the application of mechanical, sonic and ultrasonic vibration has a number of notable effects such as grain refinement, increased density, degassing, shrinkage, and the shape, size and distribution of the second phase.
This mechanism also operates during vibration producing grain refinement [7].

Mixed with grains of rammed earth, its elastic modulus can be reached with a minimum of brick masonry elastic modulus similar degree, which can dramatically improve the stiffness (the ability to resist deformation) of rammed earth material[3].
Grain fir wood is very popular locally because 1.) the grain fir wood has good bending and compression resistance; 2.)
The distribution of grain fir wood in the Tibetan area is wide; it has great straight texture, light material toughness, high strength, fragrant smell and insect resistant.
Load-bearing rammed earth wall window spacing should be greater than 1 meters, side window from the inner corner of rammed earth wall should be maintained above 0.75 meters, heavy tamping wall window area should not exceed 20% of the total area of the wall, furthermore, the inner wall and outer wall both should be bearing, thus can strengthen house integrity and let it become one [3]; 5.It should be reasonable to increase the column number, which can enhance the integrity of the housing and bearing capacity, reduce the bending moment, make deflection small, lower the housing deformation.

Table 1 Different coarsening conditions for preparation of alkali reduction rate Serial number NaOH [mol/L] Temperature[oC] Time[min] alkali reduction rate [%] 1 5.0 60 25 3.98 2 5.0 65 25 4.59 3 5.2 60 25 5.78 4 5.2 65 30 7.88 5 5.5 60 30 10.06 6 5.5 65 30 11.38 7 6.0 65 30 13.08 Variable-control method is used to show the influence of different coarsening conditions on alkali reduction rate.
Fiber of fabric can be clearly observed from the image textures, the surface of the fiber has large granular processes: some large and sparse grains, and some small and concentrated grains.
According to the experimental conditions and the relative molecular mass of the copper and silver, the larger grains are considered as silver particles, whereas the small particles are supposed to be copper.
Grain particles adhered on the surface of the fiber is uniform, thick, packaging the whole fiber, guaranteeing the excellent abrasion resistance and washing resistance.

In this study we used the method of packaging the aggregate grain, in which dominates the higher compacted and the lower void ratio.
Aggregates The coarse aggregates used in the study were from rolled pebble, fragmented material found in nature, usually in deep beds, the grains are retained at 4.8 mm sieve.
The fine aggregate was natural sand coming from the rivers of the region with grains that pass through a 4.8 mm sieve.
The use of Portland cement is highly dependent on the specific surface and porosity of aggregates grains [7].
Absorption is affected by several factors [18]: - Constituent materials: water (quantity and purity); cement (quantity, composition and fineness); aggregates (number, type, size, moisture and impurities); and additives (reactive or inert)

Finally, a single-term constitutive model that takes into account grain growth and cavitation was considered, see Eq. 3 - 5.
ε=KdP(σ1-fa)1u (3) d=do+cε (4) fa=faoeφε (5) Note that u is a constant which is only equal to the strain rate sensitivity, m, at the start of deformation (ε=0), d is the average grain size, do is the initial grain size, fao and fa are the initial and current area fraction of voids, respectively, φ is the void growth parameter, P and K are functions of the effective strain rate (ε) and c is a material constant.
It was meshed using 1200 bilinear axisymmetric quadrilateral elements; 300 element per layer with a total number of four layers.
Notice that model (4) accounts for both cavitation and grain growth.

Intergranular fracture took place in almost all conditions within the experiments, even in the unrecrystallized tungsten where majority of the grain boundaries are parallel to the tensile direction.
In addition, the recrystallized tungsten tested at strain rate of 1.4×10-3 s-1 had greater number of subcracks on the surface near the fracture point than tested at higher strain rate, as shown in Fig. 7.
Although explicit evidence is lacking, these subcracks as well as the main crack seemed to be along grain boundaries and environmental embrittlement probably by oxygen from the air is deduced to be the cause of the lower elongation at the slower strain rate.
This implies the fracture occurs at grain boundaries even in the unrecrystallized (fibrous) microstructure.
This may be caused by alleviation of some environmental embrittlement, probably associated with oxygen in air. 3) Intergranular fracture took place in almost all conditions within the experiments, even in the condition with relatively large elongation or even in the unrecrystallized tungsten where majority of the grain boundaries are parallel to the tensile direction.

Compound Percentage (%) A B C Wustite 79.3 54.3 28 Fe2SiO4 12.3 0 0 Magnesioferrite 0 29.2 0 Iron nickel (FeNi) 8.4 16.5 14.8 Quartz 0 0 47.8 Hercynite (AlFeO) 0 0 9.4 Effect of carbon type variation on the morphology Based on Figure 5, the type of reducing agent affects the grain size, affects the number of grains more and more, and the distribution is more even.
The type of reducing agent with carbon content below 70% and above 90% causes a change in the size of the resulting grain.
For example, iron-nickel is formed at a size of 5-10 um under optimal conditions if the nickel iron grains are getting bigger it will reduce the nickel content value and trigger the formation of impurities with palm shell charcoal as a reducing agent.

At the same time ,its crystal grains are surrounded with a great deal of glass phases and numerous connected air pores so the density of CBS1 sample reaches the minimum of 2.37 g/cm3.
Especially in CBS2 glass ceramics sample(Fig. 6(b)), its crystal grains are extremely small particles with the lower limit of diameter to 0.1μm.
As the B2O3 content increases further, the grain sizes of the CBS3 sample(Fig. 6(c)) gets bigger up to 0.4μm, otherwise, the size and number of pores decrease relatively.
When the content of B2O3 reaches to 21 wt. %, the crystal grains of CBS4 sample(Fig. 6(d)) become much bigger but are piled up and intensely.