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The microstructure consisted predominantly of ferritic grains and a small amount of cementite segregated incoherently at the boundaries of the ferritic grains (Fig. 5).
There are bands of different grain sizes, a large number of complex elongated inclusions composed of gray grains and darker binder and individual smaller inclusions.
Gray grains (Spectra 1 and 2) are Fe oxides with a small amount of Mn; the dark gray binder between grains (Spectra 3 and 4) are Si oxides with Si, P, Ca.
Grey grains (Spectra 1 to 3) are formed by Fe oxides with a small amount of Mn again.
The microstructure was formed by bands with grains of different size and a large number of inclusions whose length and complex composition are not present in today's steels.

The cellular method for calculating the fractal dimensions of an object is based on the Hausdorff formula [10]: , where N – a number of l-sized cells that cover the test object.
In the point method, the dimension D was calculated from the relation [11]: ~, where P(m,L) - a probability of the content of m points (cells) of a fractal in an L-sized cell, and - an average number of cells that cover an object.
Relationship between the topological invariants of feldspar grains (a), large pores (b) and large fractions of quartz (c) and the strength Large grains of sand are in the cement-sand matrix.
They can fill the space between the grains of a large aggregate, which is expanded clay.
Large quartz grains are generally rounded, i.e. smooth, and stronger than feldspar grains.

Heavy refinement grain/subgrain structure are in surface areas.
In the middle of the specimens microstructures are rather heavily cold rolled than ultrafine grained ones.
With prolongation aging temperature and time, the precipitates lost coherence with matrix and amount of the particles within matrix decreases in number Fig.1c.
Increase of temperature and aging time results in increase of grain size and decrease in density.
Area fraction of the ultrafine grains reached about 40% for sample after aging at 700oC/24h.

After annealing, nearly equiaxed grains were formed.
The number of grains examined was about 250 in each case.
The size of the grains in this material was approx. 20 µm.
The grain size after consolidation was approx. 1µm.
The structure consisted of oblong grains located in the deformation bands and nearly-equiaxed grains.

Not long ago, crushed stones of any quality, even not fractionated ones with a high content of sand, soft and clay rock grains, or flaky grains have widely been used in construction, but the current situation has dramatically changed.
Thus, the use of a three-stage crushing technology with a washing unit and a centrifugal crusher as a cube cutter may reduce the yield of flaky grains, avoid regrinding, and remove weak off-spec grains from the total mass.
The number and composition of experimental samples are given in Table 1.
The Number and Composition of Experimental Limestone Samples Item No.
Dependence of the Limestone Frost Resistance on the Content of Flaky and Cuboidal Grains Fig. 5.

Nano-structures lead to grain-boundary strengthening by dispersoids and decrease in the effective size of a weak grain boundary acting as a crack initiator by grain refinement [1-3].
Precipitation of dispersoids during sintering ensures suppression of further grain growth by impeding grain boundary migration.
Microstructure and grain growth It has been revealed that MM processes for pure W powder produce nano-W grains by the following steps: Nano layer structure → Nano subgrains → Nano W grains [27, 28].
This difference can be attributed to the presence of a large number of nano-size Ar-contained bubbles (marked by the arrows in Fig. 2), which likely give the pinning effect similar to fine dispersoids and inhibit grain growth.
The nano-structured compacts exhibited a much smaller number density of irradiation-induced voids than pure W, accompanied with no radiation hardening as measured with Vickers microhardness, although pure W exhibited a considerable hardening of ∆HV = 98 (Fig. 9).

By comparison, there are large numbers of the fatigue curves and strips in region, and the fatigue curves are made of the fatigue striation, as shown in Fig.3 c).
The size of the recrystallized grains is nearly equivalent to that of the grain boundary at the fracture surface.
Because of low strength of the grain boundaries, fatigue cracking first occurred along the grain boundaries perpendicular to the main stress axis near the exhaust edge, where greater stress existed.
In addition, it is found that the absence of some rarefaction and inclusion in the crack region, the size of recrystallized grain is match to the grain size of fracture region.
Following the recrystallizated grains generate during heat-treatment, some white particles with high concentration of W are precipitated at the grain boundary.

The samples were numbered as S1, S2, S3.
On the fractured surface of S2 (Fig.3(b)), reunion phenomenon still existed, and the number of coarse grains of TiB2 was increased.
But on the fractured surface of S3 (Fig.3(c)), neither reunion grains nor coarse grains were found.
The path of crack propagation of S3 was relatively tortuous, and the number of crack bridging was increased.
Using direct heating-up mode can also acquire uniform grains, reduce the number of coarse grains and reunion grains.

There are great differences in the grain size of the original microstructure and the average grain size is approximately 2.4 μm.
This is because there is no enough time for energy accumulation and lower grain boundaries mobility, and a large number of dislocations are generated around the B4C particles.
The numbers on the contour lines describe the efficiency of power dissipation and the shaded domains indicate the regions of flow instability (negative flow instability parameter).
The average grain size is up to 2.07μm.
However, there are also a small number of voids in the matrix around the particles.

The preliminary work demonstrated that 'H-phase' materials exhibited a number of properties including high strength, modulus, and damage tolerance at room temperature, as well as high electrical conductivity [4].
The grain size of Cu was determined by the linear-intercept technique, and more than 400 Cu grains were examined.
The grain size of pure copper was 27 µm.
The Ti2SnC decorates the grain boundaries in the mixed composite and acts as inhibitor for grain growth.
The fine grain size and the existence of Ti2SnC particles on Cu grain boundaries might contribute to the excellent high yield strength.