Search results

Each point corresponds to the total number of hillock phases within 100 Am width of a line.
For Pb atom injected into Sn-phase grains, the corresponding volume size factor Ωsf is + 29.05 % [7]; it is equal to zero for Pb atom into Pb-phase grains.
Similarly, for a Sn atom injected into Pb-phase grains, its Ωsf is -8.25% [7].
Again, it is equal to zero for Sn atom injected into Sn-phase grains.
It is easier for Sn atom to move into the Pb-phase grains rather than into Sn-rich grains at low temperatures.

Meanwhile, the pore number decreases.
The size and shape of pores change with grain growth.
Simulated images of grain growth and pore evolution.
Conclusions The images of pore evolution are obtained for practical ceramics during the grain growth, including the number, shape and size of pores.
The pore shape changed from interconnected channels to isolated sphere and pore number decreased during grain growth process.

It is dependent on not only the number of grain-boundaries but also an intrinsic varistor-voltage (= Vgb) at a grain boundary.
Therefore, it is necessary for them to independency clarify effects of the number of grain-boundaries and Vgb.
By the way, in the functional layer at the lower limits, since the number of grains between inner electrodes is around 6 to 7 in the direction of the electric field, the varistor-property at a grain-boundary should be gradually dominated with decreasing in grain-boundaries.
It is suited for MLCV as it is consisted of fine grain (average grain size = 2.3 μm).
Fabricated MLCV was thickness of functional layer of 17μm and the number of about 7 grains between internal electrodes of Au.

If the new orientation is accepted, the site may belong to other grain, otherwise the site belongs to the old grain.
Effect of Fabrication Temperature on Grain Growth.
The migration velocity (v) of grain boundaries can be given by the following equation [7] 2 2 2 exp exp m a a a AZV S Q v h R RT r γ   ∆    = −           (1) where A is the accommodation probability, Z is the average number of atoms per unit area at the grain boundary, Vm is volume of specific mol, a is Avogadro's number, h is Planck's constant, R is the gas constant, T is absolute fabrication temperature, aS∆ is the activation entropy, aQ is the activation energy, γis grain boundary energy, and r is grain boundary curvature radius.
The simulation time is expressed in term of the number of Monte Carlo Steps (MCS).
So, the atoms at the grain boundary diffuse faster and the rate of grain growth is also higher at the higher temperature.

The ECAE was carried out at the pass number of 4 times and at 623 K.
Although there was a little difference in microstructure between 4-pass and 8-pass specimens, the grain size was decreasing with increasing the pass number.
The α-Mg grain size of 4-pass specimen processed at 623 K was about 6.5 µm.
Although the yield strength and elongation were increased with increasing the number of passes, the tensile strength was saturated at the pass number of 4 times.
(2) Refinement of α-Mg grains and dispersion of the LPSO phase was caused by the ECAE process.

The grains, which formed at the old grain boundaries, possess a characteristic of 'necklace' and are of only one-tenth of the size of the original grains and 2-5 times of that of subgrains.
The result shows that there are a considerable number of fine grains possess high angle boundaries while some boundary misorientation is of medium value.
The grains may then become flattened and the size of boundary serration will become comparable with the grain thickness.
An equiaxed microstructure with a large number of high angle boundaries is therefore evolved by such a process of boundary impingement without the operation of any new recrystallization mechanism [9].
Very fine equiaxed grains possessing large-angle grain boundaries with their neighboring grains develop as a result.

In the absence of such a simple relationship we have therefore in the present work run a large number of simulations where we systematically, over a large range of values, have varied the stored energy, the nucleus size and the initial grain size.
First a microstructure is mapped onto a 3D lattice where each lattice site is assigned a number Si, which has a value between 1 and Q.
Si corresponds to the orientation of the grain, and Q is the total number of orientations.
In the following we have therefore carried out a large number of simulations where these parameters have been varied systematically.
The plot shows average initial grains with size 1, 3, 9 and 20 lattice sites together with a case where one large grain occupies the entire lattice.

A large number of dislocations appeared when warm deformation was introduced and the size of the intragranular precipitates changed differently when the deformation was changed from 10% to 30%.
The dislocations tangle with each other in the intragranular and piled up around the grain boundary.
When the density of dislocations was low, trapping of vacancies would be reduced and the rest cannot offer enough nucleation and transformation positions leading to a decrease of the number of GP-zones and a coarsening of individual precipitates.
When the density of dislocations was high, it would not only restrain the formation of GP-zones, but also lead to an increased formation of equilibrium phase η transformed from η’ phase, which also decrease the number of η’ phase.
TEM micrographs of grain boundary precipitates of SPT6, SPD2T6 and SPD3T6 samples are shown in Fig.7.

However, a number of failure mechanisms ultimately limit final ductility and formability.
Its early application was primarily for production of specialty aerospace and niche automotive components in small numbers [3].
The data of Figure 3(a) clearly show the superplastic response of fine-grained AA5083 (d = 7 µm), which produces significantly larger tensile ductilities than do the coarser-grained AA5182 and A5754 materials.
As Z increases, the apparent trend is toward convergence of tensile ductilities between the fine-grained and coarse-grained 5000-series materials.
Figure 3(b) presents data from coarse-grained Al-Mg and Al-Mg-Mn materials.

The high frequency semicircle can be attributed to the grain property of the material arising due to parallel combination of grains resistances Rgb and grains capacitances Cgb of the bulk material as shown in Fig. 1(b) inset.
These double semicircles of YIG: Bi sample is likely to result from its pretty high resistances of both grains and grain boundaries.
In such a mechanism, the number of the charge carrier is dominated by a factor that increases with temperature exponentially.
From Fig. 2(b) it can be seen that the slope of the line for grain boundaries is greater than that for grains.
The difference of activation energy (barrier height between hopping sites) in the interior of grains and at grain boundaries is quite probably because the interior of grains and grain boundaries possess a different chemical environment.