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As can be seen, the grain size decreases with an increase in the number of thermal training.
Fig. 7 Grain size of thermo-mechanically trained sample.
Fig. 6 Grain size of thermally trained samples.
To discuss the above phenomena quantitatively, the grain size of each samples are evaluated from the microstructures, and plotted against the number of thermal training.
This is because the grain size of thermo-mechanically trained sample is increased by further training, and the damping capacity is owing to the number of damping sources per unit volume.

ECAP resulted in predominantly submicrocrystalline structure with high angle grain boundaries and grain sizes ~ 100-400 nm in Al-6.1%Mg-0.3%Sc-0.1%Zr alloy and ~ 300-700 nm in Al-6%Mg alloy.
ECAP was carried out using the samples of 20 x 20 x 120 mm at a temperature of 200o C at an angle of 90 o between the channels and at a number of passes N=4 (for the Al-6.1%Mg-0.3%Sc-0.1%Zr alloy) and 6 (for the Al-6%Mg alloy), which corresponds to a true strain of ~4.5 and ~ 6.8, respectively.
ECAP resulted in predominantly submicrocrystalline structure with high-angle grain boundaries and grain sizes of ~100-400 nm in the Al-6.1%Mg-0.3%Sc-0.1%Zr alloy and ~ 300-700 nm in the Al-6%Mg alloy.
Results and Discussion The structure of aluminum alloys before and after ECAP consist of the matrix grains and large inclusions witch size is 8-11 µm in dia.
ECAP resulted in predominantly submicrocrystalline structure with high angle grain boundaries and grain sizes ~ 100-400 nm in Al6.1%Mg-0.3%Sc-0.1%Zr alloy and ~ 300-700 nm in Al-6%Mg alloy (Fig. 1).

After a designated number of cycles one stem can be replaced by an extrusion die so that the predeformation and extrusion can be performed with out any discontinuity out of the same container (Fig. 5).
The reciprocating extrusion leads after 4 cycles and indirect extrusion to a fine grained microstructure with a grain size around 3 µm.
An increase in the number of cycles up to 10 does not result in a finer or more homogeneous microstructure.
Because of the finer grain size of the predeformed billet material the more grains rotate towards a favorable orientation for the deformation [9].
These elongated grains can also be found in the products of the extrusion into a counter pressure.

The inset of Fig. 3(a) shows the grain size is small and the number is few.
The Fig.3(b) shows grain size between 30-40 nm, the grain sizeis uniform, but the grain number not much.
Fig. 3 (c) shows the grain size between 60-70 nm, uniform distribution and regular shape.
Fig. 3 (d) shows that Grain growth are connected together and agglomerates.
The crystallization sample with better uniformity of grain, grain size is small, and through the refraction of light scattering loss less, kept high transmittance.

By an increase in the solid fraction, the average grain size increases.
On the other hand, stirring the melt for a few seconds causes the displacement and distribution of these grains throughout the melt and accordingly, the grains become more spherical.
The effect of primary solid phase fraction on its grain size (and average area) and spheroidicity is shown in Fig. 6.
It can be said that by increasing the amount of primary a-phase, the average grain size (and average area) increases.
Refinement of the grain size of the LM25 alloy (A356) by 96Al–2Nb–2B master alloy.

(b) Inside the ferrite grains, laths running perpendicular to the grain boundaries are visible.
Mainly polygonal grains are observed that are likely the boundaries of the austenite at high temperature, with thin laths about 0.2-0.5 μm running perpendicularly to the grain boundaries of these polygonal grains.
The images of the microstructure show grains with irregular grain boundaries (Fig. 4).
Mainly grains with irregular grain boundaries consistent with massive ferrite are observed (Fig. 7).
The smaller values recorded for the slowly cooled alloys agree with the observation of a large number of Cu precipitates in the ferrite grains in these specimens.

As can be seen from Fig. 4(b), there are a large number of small cleavage planes and tearing ridges in the matrix, and a large number of dimples exist in the matrix around the graphite sphere.
This is because annealing significantly reduces the pearlite content and the ferrite content increases significantly, also the grain size increases and the grain boundary area decreases, so the grain boundary peak strength decreases.
Since the grain boundary internal friction is the product of the grain boundary displacement and the resistance [12], and the grain boundary sliding resistance is inversely proportional to the temperature, the grain Boundary Peak of the sample drifts to a low temperature after annealing.
Therefore, the number of interstitial atoms dissolved in the ferrite is significantly increased.
First, the area of the grain boundary is reduced after annealing.

When temperature is above 120 ℃, the bond G breaks and Mg17Al12 disrupts, so it can not play a role of locating the grain boundary and controlling the grain boundary of high temperature.
According to the EET, there are 15 kinds of covalent bonds which can not be neglected in the crystal cell of Mg17Al12, their bond name (α=A, B, … O; u and v represent the random two atoms which form the bond α, respectively), experimental bond length and equivalent bond number (the fore 7 stronger covalent bonds ) are shown in Table 2.
In like manner, Mg17Al12 or Mg2Si precipitated by grain boundary can effectively obstruct the transfer of grain boundary slipping and make it more difficult to start the slipping of adjacent grain boundary so that the strength of the alloy is improved.
The strength of bond A of Mg2Si is three point seven times as big as that of bond G of Mg17Al12, so the melting point of Mg17Al12 is 437 ℃ and that of Mg2Si is 1089 ℃.When temperature is above 120 ℃, bond G of Mg17Al12 in the grain boundary of Mg-Al alloy disrupts, Mg17Al12 begins to soften and can not play a role of locating the grain boundary and controlling the grain boundary, this induce the persistent strength of alloy reduced rapidly.
When temperature is above 120 ℃, bond G of Mg17Al12 in the grain boundary of Mg-Al alloy disrupts, so Mg17Al12 can not play a role of locating the grain boundary and controlling the grain boundary under high temperature.

Samples containing large grain sand and slate were chosen for the subsequent industrial scale preparation.
Since that moment, the use of EPS has grown exponentially in a number of different fields.
Consequently, this material poses a number of industrial applications [2].
Finally, if the fine grain sand is substituted by slate or granite (series S and G, respectively) a noticeable increase in the weight loss is observed.
The sample exhibiting the best properties is the one in which calcium carbonate has been substituted by fine grain kaolin.

On the other hand, the decrease of crystal grain size after the laser beam heating is visible.
This means the grain sizes in PZT thin film decrease due to the laser beam heating, the result is in good agreement with the conclusion [15].
First, the grain sizes in PZT thin film decrease due to the laser beam heating.
The small grains result in the degradation of FE thin film, and large grained films show a more steep polarization curve [16-18].
(2) After a laser pulsed heating, the small grained films with the high X-ray diffraction peak have more smooth polarization curve because of the fined grain effect of PZT thin film due to the single pulsed laser heating.