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The microstructures of the solidified ceramics presented a number of fine TiB2 platelets embedded in TiC grains, Cr-Ti alloy or between TiC grains and Cr-Ti alloy.
FESEM images and EDS results showed that a large number of TiB2 platelets were embedded in the irregular TiC grains, Cr-Ti metallic phases (showed by the white area in Fig. 2) or between TiC grains and Cr-Ti metallic phases, as shown in Fig. 2.
However, mole concentration of Ti and B actually decreases because of the addition of liquid metallic Cr in liquid TiC-TiB2, making a number of TiB2 platelets grow more hardly.
As discussed above, the increased mass fraction of Cr binder not only makes fine-grained even ultrafine-grained microstructure achieved in the ceramic, but also brings about the increased plastic phases of Cr-Ti alloy.
FESEM images and EDS analyses showed that current solidified TiC-TiB2 composites were composed of TiB2 platelets, irregular TiC grains, Cr-Ti metallic phases and a few of isolated Al2O3 inclusions, and a number of fine TiB2 platelets were embedded in TiC grains, Cr-Ti alloy or between TiC grains and Cr-Ti alloy.

A remarkable decrease of the grain boundary effect was found at the tempering temperature of 673 K, which is due to a disappearance of film-like carbides on grain boundaries.
Although the block structure, which is smallest unit with high-angle boundary, is analogous to the effective grain, it is still hard to measure the grain size in µm scale and control the grain size experimentally to get a Hall-Petch plot.
As dislocations pile up on a slip plane against a grain boundary stress is transferred to the adjacent grain.
The shear stress τ at the dislocation source in the next grain is expressed as τ = ατs(L/r) 1/2, (1) where α is an orientation-dependent factor close to unity, τs is the average resolved shear stress on the slip plane, L is the distance along the slip plane between the head of the pile-up and the hindward dislocation source, which is directly proportional to the number of pile-up dislocations, and r is the distance from the head of the pile-up to the forward dislocation source in the adjacent grain [17,18].
In this way, a rocking parameter k can be semiquantitatively evaluated using data of nanohardness and grain size for just one sample without changing a grain size to have a Hall-Petch plot.

The increasing number of ECAP passes influenced particularly homogeneity of microstructure and the number of high-angle grain boundaries (HAGB).
The EBSD data indicate that the number of high-angle grain boundaries (θ>15°) measured in the samples after ECAP and subsequent creep exposure is strongly dependent on the number of ECAP passes (Fig. 7).
In the areas with the higher number of HAGB the grain boundary sliding will be more intensive than in the surrounding areas [8].
The dependence of number of high angle grain boundaries on the number of ECAP passes.
The number of ECAP passes effects homogeneity of microstructure and the number of high angle grain boundaries.

This "expansion" of the region where two grains meet is referred to as a grain boundary excess free volume (BFV).
Along with the grain boundary energy it belongs to the fundamental thermodynamic properties of grain boundaries and thus, directly correlates with grain boundary properties such as grain boundary diffusion, sliding, wetting, etc.
The parameter 0Γ has the meaning of autoadsorption on grain boundaries in a pure material and is defined as the difference between the number of atoms in a bicrystal *aN and in a single crystal of the same volume aN per unit area of a boundary: ( )*0aa NNA Γ= − % , where A% is the grain boundary area1.
Prior to annealing the samples were electrolytically polished to improve the surface quality. 40θ=° <111> II <111> I <111> III <112> III <110> Grain I Grain II Grain III ψ <112> I <112> II <110> GB3 °= 42 GB1GB2 ψ ψ 40θ=° <111> II <111> I <111> III <112> III <110> Grain I Grain II Grain III ψ <112> I <112> II <110> GB3 °= 42 GB1GB2 ψ ψ Fig. 2.
Shvindlerman: Grain Boundary Migration in Metals.

Inhomogeneity of grains in Fig. 1 (a) and (b) shows austenite grain growth trend that big grains swallow small ones.
a b c e d f Fig. 1 Variation AGS RE steel held at different austenitizing temperatures for 5min: (a) 1130 , (b) 1160 , (c) 1190 , (d) 1220 , (e) 1250 , and (f) 1280 Table 2 Experimental data of AGS of steel, isothermally treated for 5 min at different temperatures Temperature, D, μm ASTM grade, G steel A steel B steel A steel B 1130 62.7 60.4 4.7 4.8 1160 78.4 73.9 4.1 4.2 1190 88.5 82.9 3.7 3.9 1220 95.3 88.1 3.5 3.7 1250 105.1 102.2 3.2 3.3 1280 133.2 120.0 2.5 2.8 Fig. 2 Effect of soaking temperature on Fig. 3 Relationship between austenite austenite grain size grain size and soaking temperature AGS is smaller at lower temperature than high Niobium because there are a great number of second phase particles in the steel below 1250 .
These second-phase particles can pin austenite grain boundary and effectively prevent austenite grain growing in heating process.
Most grain boundaries intersect angle is (or close to) 120°, grain size more equalization and shape relatively steady.
Therefore, the effect soaking temperature on grain growth actually is atomic of grain boundary in steel across the grain boundary migration the impact of diffusion process.

Si and Mg2Si precipitated in the grain boundary of these two materials.
The weld penetration into the grain of the precipitates and a decrease in the precipitates on the grain boundaries can be considered as reasons for this improvement.
Moreover, an increase in the fine dispersion of the precipitate (Si, Mg2Si) in the grain and grain boundary were caused by the artificial aging treatment.
The fine grains are thought to be related to the increase in strength.
Forging of the artificially aged material produced fine grains and decreases the number of precipitates at the grain boundaries. 3.

The larger number of crystal nuclear are formed and the even shape and size grains are obtained.
By comparing with Fig.2 b),c),d), it can be obviously observed that crystal structure grows more even and regular and the number of grain grows more and the grain is refined.
It can be concluded from Fig.2 that slope length has significant effect on the grain number and shape of the alloy microstructure.
It can be observed that crystal structure grows more even and regular and the number of grain grows more and the grain is refined when the vibration voltage grows higher until to 80v.
So the broken arms can be new nuclear which increase the number of grain.

Fine-Grained High-Strength Concrete N.P.
The structure of fine-grained concrete is studied.
Despite the larger optimal diameter of the metakaolin particles, stabilized by PVA after 8 minute ultrasonic dispersion, the number of the particles with the size of 11.2 nm is 44.3%, thus it being 4 times more than the metakaolin particles with the minimum diameter when stabilizing the suspension with S-3.
Structure of fine-grained concrete modified by PVA (a) and S-3 (b).
Goldenberg, Fine-Grained Concrete, MGSU, Moscow. 1998

Introduction Although the first research on intercrystalline diffusion in nanocrystalline metals was carried out more than 20 years ago [1], up to the present time there is not a full understanding of specific features of the diffusion processes in such materials, and the number of studies dealing with the experimental investigation of diffusion in them is relatively small [2].
At the annealing the Mössbauer isotope atoms diffuse along grain boundaries.
As shown in [17-20] grains between agglomerates are the fastest diffusion paths in such materials while the diffusion properties of boundaries between nano-grains are the same as in coarse-grained materials.
As demonstrated by TEM in [28], grain sizes after such treatment are about 100 nm, and grain boundaries are wide and non-equilibrium, a complex diffraction contrast and moiré inside grains testifying high internal stresses.
At heating up to 873K grain sizes remain unchanged but recovery occurs, grain boundaries becoming thinner and straighter and grains clearing of dislocations, and at higher temperatures recrystallization starts with intensive grain growth.

Images are stored in computers as matrix of number representing each pixels value.
In Fig.1 a) is shown a method according to which each grain is numbered by an operator and in Fig.2 b) is a model-image method where operator compares the samples with the models.
The aim of edge detection is to identify the grain boundary.
The SVM model provide as output contours of the grains in a vectorial information, as well as statistical analysis concerning different information such as grain surface and grain shape.
The automatic measurement method proposed in this paper based in SVM approach measure grain size via grain boundary reconstruction.