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The mechanical milling is a complex process which involves the optimization of a number of variables to achieve a desired phase or microstructure [1].
MA of Fe–Al based alloys has been the subject of a considerable number of studies; Fe–Al–Ni [16], Fe–Al–Ti [17], Fe-Al-Cu [15].
Firstly, with decreasing the grain size, the volume fraction of grain boundaries increases.
When the grain size is smaller, the magnetic exchange length, domain wall effect diminishes and each grain reacts as a single domain.
The coercivity of crystalline alloys depends strongly on grain size because the magnetic domain walls interact with the grain boundaries [24].

The improved NH3 sensing ability caused by shrink electrode spacing is attributed to the presence of more grain boundaries and depletion layers.
It is known that more grain boundaries and depletion layers could enhance the sensing responses [4].
These crossed networks of ZnO nanorods cause more grain boundaries and deplection layers [4, 6].
Besides, with shrinking the electrode spacing, the numbers of networking points of ZnO nanorods are increased.

In that sense, electrical impedance spectroscopy was also tried, since contributions of grains, grain boundaries, pores and other morphological aspects might be discriminated [7-9].
The increase of the sintering (dwell) time promotes the dissolution of the mullite grains in the glassy phase and a consequent increase of the volume fraction of glass, in spite of the enlargement of the mullite grains.
However, the dependence of the grains shape can be determinant, and the acicular configuration of the mullite grains might impose significant alterations.
With the aim of reducing the number of independent variables, the model was applied to the obtained results at different temperatures, by keeping constant the morphological parameters (t = 0.65 and fc = 0.644).
This high value can be justified by the acicular morphology of the mullite grains.

The practical application of ultrasonic technologies in this area, however, faces a number of technical challenges.
As a result, the ability of refiner to nucleate new grains is drastically improved.
Moreover, newly nucleated grains (in our case primary silicon) can grow and agglomerate with each other to form larger grains.
In the figure, the dark particles correspond to the grains of primary Si.
Fig.3 Variation of mean diameter of primary Si grains with dimensionless distance from the billet center.

In this form, loading abrasive grains and/or machined chip to the pores of grinding stone, machinability of grinding stone is gradually decreased.
Effect of grain size on finished surface roughness.
Figure 10 shows the variation of the surface roughness depending on the different grain sizes of grinding stones.
That is, in case of using #3000, the number of contact abrasive grains is larger than in case of #1000.
However, the load acting each contact grain is small and machining may not be carried out efficiently.

This recovery process can be explained by following equation: n d wi wi 2 , annihil climb , 2 ρ νρ = −& , (3) where ρi,w describes the immobile dislocation density as well as the dislocation density in the cell walls, dannihil the critical distance for dislocation annihilation and n the number of active gliding systems.
Due to accumulation of dislocations during the deformation process, energy is stored at high angle grain boundaries and this energy decreases by the nucleation of new grains during high thermal conditions.
, (8) where CGB is a constant and SGB is the density of overcritical nuclei at grain boundaries.
The grain structure shows large grains, extending the EBSD-image, which could be some hundred microns long, and smaller grains also showing elongated structure.
Hence the comparison of simulations and experiments show a good correspondence with regard to grain and grain and subgrain size (compare Fig. 5b and Fig. 6) of the air cooled condition.

Base on the result of simulation, a great number of experiments about the water cooling plan to the outside flange has been implemented in the manufacture line.
Meta-dynamic recrystallization Static recrystallization model Recrystallization Grain Growth Model Meta-recrystallization model： As time of grain growing after deforming is， As time of the grain growing after deforming is , Static recrystallization model ： As time of the grain growing after deforming is， As time of the grain growing after deforming is, Average grain size and residual strain The transformation of austenite to other phase, which is occurred in the lower temperature, would appeared during the rolling.
The Austenite Grain Size in different TM pass Figure 9 shows that the grain size of web and the flange reduced during the rolling of tandem machine, but in the whole rolling process the grain size of web is much smaller than the flange whereas in the connection area of web and flange the grain size is always the biggest.
The ferrite grain size distribution result could be acquired by the same way as the operation to austenite grain size.
The web has the smallest grain size whereas the connection area of the web and the flange has the biggest grain size.

A number of FSW experiments were carried out to obtain the optimum mechanical properties by adjusting the rotational speed to 1000 rpm and welding speed in the range of 14-112 mm/min and with an adjustable offset of the pin location with respect to the butt line.
For analyzing the influence of welding speed on the microstructure and mechanical properties of friction stir welded plates of copper and stainless steel, a number of experiments with welding speeds of 14, 20, 28, 40, 56 and 112 mm/min have been done.
Base 304L stainless steel has an austenitic microstructure with equiaxed grains.
The size of grains grows significantly in the HAZ of retreating side but the situation is different in the advancing side and there is a small grain growth in transition from base to HAZ.
The size of grains is significantly decreased in the nugget zone due to dynamic recrystallization during the welding process.

The formula reflects the relationship between the grain maximum allowable heating temperature and the initial water content and heating time, it also shows that the lower moisture content of grain, the higher grain maximum allowable heating temperature [6].
Grain drying quality control technology.
Grain storage (1999), p.23-30
The broken reason of Corn grain of Corn dryer system.
Grain Distribution Technology, (2003), p.29-30

Its advantages are a short production chain, low energy and material consumption, as well as smaller production areas and a decreased number of servicing personnel [1].
The dendritic grains in this case undergo additional straining; however, unlike the symmetric TRC, the grains are not elongated in the rolling direction.
The grains in this case are slightly finer, which leads to the improved strength properties.
This results in a slight grain refinement and allows an equiaxed grain structure to be reached during the subsequent annealing.
Zhang, Shear deformation and grain refinement in pure Al by asymmetric rolling, Trans.