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However, the widespread application of the Mg alloys is seriously restricted by two principal drawbacks: low ductility at room temperature due to limited number of available slip systems and poor weldability.
Therefore, a number of research efforts were undertaken recently in an attempt to clarify this issue [6-10].
The microstructure consists of low-aspect ratio grains with an average grain size of ~19 µm.
Formation of the fine-grains along the original grain boundaries significantly decreases the average grain size and somewhat reduces the LAB fraction in Region 4 (Table 1).
This also may give rise to the fine equiaxed grains along the original grain boundaries.

Sample number 1 shows the highest passive current, the second one is sample number 2, then number 3 and number 4.
Passivation potential of sample can be ranked from high to low as below: number 1, number 3, number2 and number 4.
Sample number 1 has the highest passive current, the second is number 3, the third is number 2 and the last is number 4.
Passivation potentials of samples can be ranked from high to low as below: number 1, number 2, number 4 and number 3.
It must to be pointed out that sensitized sample number 4 shows worse passivation properties than number 3, the reason might be number 4 has a higher carbon content, after sensitization much more chromium carbides precipitate near grain boundary leads local chromium depletion.

With the increase of dressing depth, surface peak and valley values of elliptical ultrasonic vibration dressing grinding wheel increases, while the number of static effective abrasive grain reduces.
(a) Elliptical vibration amplitude transformer (b) Dressing System Fig. 1 Test Tooling a Longitudinal vibration feature b Transverse vibration feature c Synthesis of vibrations Fig. 2 The Elliptical Vibration Measurements Dressing Conditions:To distinguish between resin bonded diamond grinding wheels and metal bonded diamond grinding wheels, R and M is added respectively before the corresponding size number as prefix, such as, R100 refers to resin bonded diamond wheel with the grain size of No. 100, MW10 refers to metal bonded diamond grinding wheel with the grain size of No.
With increase of dressing depth , the surface peak and valley values of elliptical ultrasonic vibration dressing wheel increase, that is the protrusion height of abrasive grain increases, while the number of static effective abrasive reduces; ordinary dressing grinding wheel surface has a similar variation feature, but the number of static effective abrasive reduces faster and abrasive distribution is more irregular.
With the increase in dressing depth, the surface peak and valley values of elliptical ultrasonic vibration dressing wheel increase, that is the protrusion height of abrasive grain increases, while the number of static effective abrasive reduces; ordinary dressing grinding wheel surface has a similar variation feature, but the number of static effective abrasive reduced faster, and the abrasive distribution is more irregular.
The number of static effective abrasive is larger, while the protrusion height is higher and abrasive accordance gets better.

There are a large number of secondary α phase precipitated from the grain boundaries and within grain of β phase undergoing aging treatment.
A large number of equiaxed primary α phase is precipitated at the grain boundaries of the β phase matrix.
The grains have not been refined by subsequent aging process, but the new interface, α/β boundary, has been formed, which introduces a large number of substructures in the micrometer or sub micrometer scale.
On the other hand, the number of grain boundary per unit volume increases by grain refinement.
The grain size of α phase increases with increasing aging temperature, but the number of precipitated phase in unit area decreases with the increase of aging temperature

A number of studies have been initiated in recent years that examine the tribological and wear performance of usual silicon nitride materials with several micrometer grain size in a variety of wear environments.
Relative density and grain size.
Although the average grain size was very small at 1500˚C, the density was only 86%.
The average grain size was less than 500nm at the sintering temperature below 1700˚C.
The average grain size of sintered body is less than 500nm.

For reducing the error, we take five square areas from the profile, and every square is 100mm2 on the profile, then calculate the grain number of the square.
The result is the average ration of grain number of five square and 100, and experimental results shown in Tab.1.
In addition, the effect of pulsed electric field on the Pb-Sn alloy grain size conform some law, and the pulse frequency has greater impact on the grain size, when the pulse frequency reach 25Hz, the grain size is maximum; The pulse voltage also has some effect on the grain size, when the pulse frequency reach 250V, the refinement is significant.
Based on the thermodynamics, we can know that this kind of salvation cluster is more stable than the solute and solution ones, and the number is also dominant.
The accumulated atoms and the cluster may reorganize and form new cluster with a bigger magic number, then the atom density far away from the cluster will become low.

The Grain Boundary Wetting in the Sn- 25 at% In Alloys C.
The grain boundary (GB) wetting was investigated in the Sn - 25 at.% In alloy.
Figure 1 A grain boundary (GB) and two adjacent grains in equilibrium contact with a liquid phase L and the dihedral angle θ. θ > 0 because 2σSL ≥ σGB Figure 2 GB energy σGB and interphase boundary energy σSL decrease with increasing temperature.
The grain size of these specimens was approximately 200 µm.
If the In atoms in grains of 25% In reveal about 400 counts (Fig. 6a), the average number of 800 counts in the GB region corresponds to the equalmolar of Sn and In in GBs.

Samples were subjected to various numbers of FSP passes from 1 to 3.
FSP offer low energy consumption route to introduce reinforcing phases into the metal matrix and to form bulk composites, grain refinement and grain boundary pinning [5].
The effect of excess heat generated at high shoulder rotational speed on grain growth is eminent.
Increasing the number of FSP passes works in favor of high hardness while high rotation speed leads to softening effect, grain growth and stress relive and therefore it deteriorates hardness.
Increasing the numbers of FSP passes results in more uniform dispersion of Al2O3 particles.

Grain boundary diffusion and grain boundary segregation.
Mechanisms of grain boundary diffusion.
Unfortunately, due to different reasons (the work with the radioactive elements is a health hazard, the radioactive isotopes are expensive, etc.) the number of laboratories employing autoradiography falls and, consequently, the number of results is strongly reduced.
A large number of GB diffusion data has been obtained to date, gathered in different handbooks, such as [4,31] and also in the journal "Defect and Diffusion Data".
Over recent years such data have been taken in a number of systems, particularly for different solutes in Cu [40,41,43] and quite recently in ultra fine grained Cu [42].

Accordingly, the predicted texture evolution depends on temperature, strain rate, chemistry (solute level, particle number and size), and grain size.
Thus, the recovery kinetics scale with the number of slip systems, NGLS, as developed by GIA.
For nucleation to occur, however, a critical number of active slip systems must be defined, and grains exceeding this number were assumed to recover fast and to form viable recrystallisation nuclei, whereas other nucleus orientations were deleted from the spectrum.
The numbers nrand, nGB and nTB can be directly extracted from the output of a GIA-3IVM simulation.
For more than 500 particles the number of nuclei per particle and their orientation were measured (Fig. 5) [42].