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It is proposed that LVECP treatment created a new dynamic factor for nucleation so that the number of nuclei increased, which restrained the formation of large primary α-Mg dendrites and created a base to form spherical crystals of primary α-Mg.
It is more intriguing to see that the grains are globular or non-dendritic in shape.
The function of LVECP discharge in this case is to alter or accelerate the melting at the root and to carry the dendrite arm away from its “mother grain” to where it can grow as a new grain, therefore, the primary α-Mg phase was refined greatly and the non-dendritic primary grains were formed.
The primary phase grains will become coarser, because the nucleus reduces.
With appropriate processing parameters of LVECP treatment, the semi-solid microstructures of AZ91D alloy were modified and the equiaxed, nondendritic grains are formed instead of large grains with dendrites

It appeared white and precipitated both within the grains and in the grain boundaries.
Figs. 3 indicated that the MC within the grains, the M23C6 in the grain boundaries dissolved and the grain grew orderly as a result of mounting heat input value.
The avg. number of cracks in Table 6 equals to the ratio of the total number of cracks to the number of samples.
Fig. 6 illustrates that M6C carbides precipitated as globules in the grain boundaries and within the grains, M23C6 formed and homogenously distributed in the grain boundaries, these two carbides phases precipitated as staggered chains of globules in the grain boundaries and the phase density in the grain boundaries was quite high thus avoiding grain growth and strengthening the alloy.
So both the phases within the grains and in the grain boundaries were partly dissolved, if certain low-melting phases have formed in the grain boundaries, then the grain boundaries would be overfired easily.

With increasing both the distance from the center and the number of turns, the sum of the volume fractions of ε- and α’-martensites increases.
With increasing the number of turns to 10 the grain size in the disk center was refined to 95 nm, as revealed by dark-field TEM images (not shown here) [19].
It is noted that the hardness increased with increasing both the numbers of revolutions and the distance from the disk centre.
When the numbers of revolutions increased to 10 the hardness reached ~5150 and ~6130 MPa at the centre and periphery of the disk, respectively.
In this specimen the grain size was refined from ~42 μm to ~26 μm and large numbers of twin boundaries were formed inside the grains.

This process also can efficiently refine the ferritic coarse grained microstructure to nano-scale grain structure with well-defined grain boundary.
Fig. 2 shows the tensile strength of groove pressed low carbon steel sheets versus annealing temperature at different CGP pass numbers.
Fig. 6b shows the microstructure of two CGP passes sheet after annealing at 400 °C that in which the grains with insignificant grain growth can be observed, yet no abnormal grain growth can be observed.
Consequently, in the grain growth process (which occurs at elevated temperatures of post-annealing), the kinetic of growth for grains with dissimilar sizes is different resulting in abnormal grain growth.
I.F. distributions with annealing temperature and CGP pass number.

The fine grain microstructure of DSS is capable of showing superplasticity at high temperature condition [6].
Microstructure of fine grain DSS carburized at 1223 K for 6 hours with initial pressure of 49 MPa Fig. 4.
Furthermore, the fine grain microstructure of DSS also enhanced the movement of carbon atoms deeper into the base material as it provides a larger number of grain boundary diffusion paths.
Initial hardness of the fine grain DSS before the SPC process is 426 HV.
Fig. 9 shows the relationship between carbon growth rate and temperature for the carburized fine grain DSS.

Results To analyze the grain size of the Samotlor field, the results of grain size distribution for thin sections were used that had been obtained by Nizhnevartovskgaz OJSC specialists and processed at TSGE OJSC by a group of scientists headed by S.B.
The number of wells where studies were undertaken is obviously insufficient for correct the summary interpretation of analysis results.
According to descriptions of thin sections, rocks primarily belong to fine-grained sandstones and large and medium-grained siltites.
In terms of the medium size, as noted above, the sediments under study belong to small-grain sand stones and large and medium-grained siltites, which can be related to low energetic capabilities of the transported medium or to the nature of the distributive province.
A large number of stripes of dynamically related subzones must be checked.

In actuator applications, the SMAs are subjected to large number of thermo-mechanical cycling which introduces defects in the material.
Fine scale grains, few tens of nanometer in size, can be seen in good contrast.
It can be noted that large number of thermo-mechanical cycles resulted in deformation bands with fragmented twinned lath structure and significant de-twinned regions.
As the number of cycles increases, the martensite variant intersections loose coherency.
On TMC, the material develops well defined martensite variants/grains.

Sintered SiAlONs are of two types with different microstructural features [22, 25]: (1) β-sialon grains plus glass, (2) β sialon grains plus crystalline YAG.
As the grain boundary composition changes, the aspect ratios of β grains vary and grain coarsening also occurs as sintering time or temperature is increased.
Effects of Grain Boundary Glass on Properties.
Grain boundary chemistry affects interfacial bond strengths.
Other practical advantages of high toughness values (KIc = 7-10 MPa.m1/2) include resistance to machining damage and improved fatigue behavior, KIc increasing with the volume fraction of elongated grains and proportional to (grain size) 1/2, an effect due to "crack wake mechanisms", such as crack bridging, grain rotation and grain pullout.

As a rule, the electrolyte with porous silver paste electrodes is equivalent to a circuit of three RQ elements in series corresponding to grain, grain boundary, material/electrode contribution.
Therefore, the impedance spectrum usually shows two or three arcs, and the higher, medium, lower frequency arcs represent the grain impedance, the grain boundary impedance and electrode polarization effect, respectively [13, 14].
The total resistance R is the resistance sum of the grain and the grain boundary.
The average ionic transport number in the given oxygen pressure range can be obtained by EMF method [6].
The oxide-ionic transport numbers drop a little under the p(O2) gradient of 0.21 atm/1× 10−5 atm, and the minimum oxygen ion transport number 0.983 is observed at 1,023 K.

These simulations couple a grain size and strain dependant viscous rheology with grain size reduction and grain growth processes.
The list of active processes includes dislocation glide, twinning, various types of sub-grain formation, grain boundary sliding, grain and sub-grain boundary migration, grain boundary diffusion, lattice diffusion, fracturing, frictional sliding, and fluid flow [5].
Grain Size Reduction There are several processes that could result in a decrease in grain size in a rock including fracturing, twinning, kinking, metamorphic re-equilibration and rotation recrystallization, all of which are replaced in these experiments by a single process that inserts an 1 http://www.microstructure.uni-tuebingen.de/elle Journal Title and Volume Number (to be inserted by the publisher) 3 approximately straight high angle grain boundary in a grain.
Grain Growth We have used a simple grain boundary migration algorithm based only on local grain boundary curvature to describe a generic grain size increase process.
Journal Title and Volume Number (to be inserted by the publisher) 5 Figure 2.