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The existence of Ba-b-Al2O3 phase as well as low sintering temperature and short holding time during reactive sintering inhibit grain growth and thus result in small grain sizes of the Al2O3 matrix.
Bright regions correspond to high atomic numbers (Ba), whereas dark regions correspond to lower atomic number (Al).
At 1400oC, the Al2O3 matrix exhibited fine grains and their average size was 0.78 mm.
With the increase in sintering temperature, grain growth occurs.
As shown in Fig. 6(b), the average grain size of the Al2O3 matrix attained 1.49 mm at 1500°C.

The number of diamond grits chosen to track the protrusion height of diamond grits in the experiment is 39.
The second mode rarely occurs, therefore it can be considered as improper failure of the diamond abrasive grain.
The number of whole diamond grits decreases in beginning phase, and the fractured, flat, break flat and pull-out increases.
The number of whole diamond grits decreases to zero.
The number of fractured, flat and pull-out rapidly increases.

Fine-Grained Concretes on Non-Clinker Binders with Highly Disperse Mineral Components D.K.
At the next stage, the number of Bronsted active crystallization centers on the surface of a mineral powder was investigated by the method of determining the exchange capacity with respect to calcium ions [9].
The results of tests to determine the number of active crystallization centers showed that the surface concentration of ion-exchange centers of mineral powders varies unevenly and does not depend on the degree of grinding (Table 1).
This can be explained by the presence on the surface of these mineral fine dispersions of a large number of exchange centers, a significant part of which are acids and alcalines according to Bronsted [6].
To study the properties of fine-grained concretes, 10 cm cubes were prepared using a mixture: a highly dispersed component (Table 2), fractionated sand, obtained by mixing in a ratio of 55:45% of the screening of the Argun deposit and the fine sand of the Chervlenskoye deposit.

The grain body was characterized by a sufficiently large number of twins of annealing and precipitates of Cu2O oxide in the form of dark gray inclusions of various sizes (from 0.3 to 5 μm) and shapes (mostly round and elongated) having a regular orientation along the rod axis and a stringer-type arrangement (Fig. 1 a).
Almost equiaxed grains are observed in the microstructure of the transverse section of the wire.
The following assumptions were made: the samples were considered as pure copper with a certain grain size.
EBSD Analysis of the Submicron Width Fibber Shaped Grain Copper Fabricated by Drawing, Mater.
Determination of grain size.

The structure of silicon grains is elongated relative to the growth direction, the dislocation density in grains is of about (5÷8) ×10 4 cm-2, the average lifetime of minority carriers is 4÷6 µs.
This results in a rather bad quality of poly-Si layers, namely in small grain size and large concentration of grain boundaries with a high concentration of dislocations acting as fast recombination centers for photo-generated electrons and holes.
Apart from using the carbon net as a substrate, we propose a number of new technical solutions to improve the crystal structure and photovoltaic quality of produced composite semiconductor material in this work.
X-rays investigations show that the main orientation of the grain surfaces are (100), (111) and (211).
We suppose that it is mainly limited by the presence of transition metal impurities collected by dislocations in grains and in grain boundaries [5,6].

But in polycrystalline metals, the grains are randomly oriented and the dislocation motions in individual grains must be restricted by their neighboring grains.
The propagation of initial fatigue cracks formed in individual grains also must be arrested by their neighboring grains.
According to their considerations, the yielding strength of a polycrystalline metal is a stress to "spread out" the dislocation motion from some weak grains to their neighbouring grains and the variation of σ y with grain diameter, d, can be expressed asσ y＝σ 0+ ky d -1/2，where σ 0 is the stress resisting the movement of dislocations along the slip plane within weak grains, while the ky is a coefficient reflecting the resistance to unpin dislocations from their source in the neighbouring grains.
Actually, the ky , as well as theσ y should be higher for a weak grain located in the interior than that for a weak grain at or near the surface.
It is because that the dislocation motion in the internal grain is restricted by the neighboring grains from different sides, while that in the grain at the surface is only restricted from the internal side and is free from its surface side.

The size of t he grains varies from 220μm to 50μm and the average size is measured to be 170μm.
A crack along the grain boundary is also found in the fracture surface.
Although there are many submicroscopic particles of insoluble solid impurities in the melt, the number of active particles is insufficient for effective heterogeneous nucleation.
Meanwhile, a large number of solid impurity particles, such as the Mn-based inter-metallic compounds, are universally distributed in the AZ91D alloy melt.
These changes were consistent with the fine uniform dendrite grains.

The microstructure of the as-deposited sample consisted of columnar and equiaxed grains, in which siliconwas distributed along the grain boundary and the grain size was about 30 μm.
Besides, some TiB2 particles converged at the grain boundary.
Besides, there was a clear division between coarse and fine grains in two directions.The existence of coarse grains and fine grains is related to the solidification process.
The reason why TiB2 particles can refine grains during solidification is that TiB2 has some co-lattice relationship with α-Al, so a small number of TiB2 particles can become the heterogeneous nucleus of α-Al, while other TiB2 particles will hinder the growth of nascent α-Al grains, thus realizing the refinement of grains [18].
According to the analysis of scanning electron microscope images (as shown in Fig. 5), the size of TiB2 particles was generally less than 1 μm, but the size of a small number of TiB2 particles could reach about 2 μm.

Four of the packets exist along the prior austenite grain boundaries and one packet grows from the boundary edge into the prior austenite grain.
White broken lines indicate the austenite grain boundaries.
Figure 3 shows 3D images of incipient-formed lath martensite regions in a prior austenite grain, corresponding to the prior austenite grain in Fig. 1.
The prior austenite grain shown in Fig. 3 has five packets in the prior austenite grain.
The number of incipient blocks with rule 1, which is the same as rule i+ii in Ref. 2, was consistent at a ratio of three over seven.

Similar results concerning Journal Title and Volume Number (to be inserted by the publisher) 3 misorientation inside the {111} <112> and {111} <110> grains, have already been reported from EBSD measurements by Lesne [4] for a 70% cold rolled ultra high purity iron and by Thomas et al
c d b a 9° 3° d c Journal Title and Volume Number (to be inserted by the publisher) 5 Fig. 5 Cell coalescence in a {111}<110> grain after 2 min annealing at 700°C.
(Arrows indicate the bulging in the neighbouring {110}<112> grain; dashed arrows indicate the growth in the "parent" grain).
Generally, the subgrains located inside the grains or at the grain boundary mainly grow inside their "parent" grain.
After cell coalescence or not, subgrains located near grain boundaries grow, either towards the interior of the "parent" grains, or in the neighbouring grain by bulging, even both.