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The image contrast arises mainly from two different effects - atomic number contrast and electron channelling contrast [0].
In Fig.1 the electron channelling contrast is sufficiently large to allow discrimination of neighbouring grains and identification of (recrystallization) twins.
The initial solid/liquid interface was orientated in the readily discernible transition zone where the morphology changes from equiaxed grains to elongated grains.
The elongated grains provide experimental evidence that planar front solidification occurred [0].

Extension of this work to polycrystalline, bulk aluminium-copper alloys also reveals interfacial enrichment of copper, but the level of enrichment is grain orientation dependent, with enhanced enrichments at low index grains.
Thereafter, the level of enrichment, expressed in terms of the number of atoms per unit area of the interface, remains approximately constant.
This effect is also grain orientation dependent, reflecting an influence of microstructure on the overall behaviour.
The population density of the clusters differs on the adjacent grains For the model S phase, anodic oxidation in near-neutral electrolyte results in barrier film formation with associated enrichment of copper in an alloy layer immediately below the anodic 3 �m alumina.

Classification of sands depending on density Sand class Sand group by density Average grain density, [g/cm³] Bulk density, [kg/m³] Dense Very heavy over 2.8 more than 1800 Heavy from 2.0 to 2.8 inclusive from 1300 to 1800 inclusive Average from 1.2 to 2.0 inclusive from 800 to 1300 inclusive Porous Lungs from 0.6 to 1.2 inclusive from 400 to 800 inclusive Very light less than 0.6 less than 400 Table 2.
Classification of sands by particle size composition A type of sand Grain size, particle d , [mm] Content of grain particles by mass, [%] Engraved >2.00 >25 Coarse >0.50 >50 Medium size >0.25 >50 Small >0.10 ≥75 Dusty >0.10 <75 Sand is extracted by river, quarry and artificial methods [10].
At the same time, the planes of separation pass along the radius of the base of the conical structure through the drains, cutting off the arc of the circle of the base of the cone and limits the central angle by the value: (9) where, S≥6 – the number of sectors formed by adjacent flows; 2α 0 is the central angle of the selected conical sector.
Results of sand dehydration research Research options taking into account the placement of needle filters H, [cm] granulometric composition [%] initial humidity, [%] final humidity, [%] grain size, particle d, [mm] 3 2.5 1.25 0.63 0.315 0.14 ≥0.14 circular 400 – 1.3 3.6 13.0 53.9 24.6 2.7 30 5–8 linear 400 3.8 9.7 5.6 6.2 27.2 46.6 4.7 30 7–10 circular 200 0.5 8.2 5.5 27.0 24.0 33.0 1.6 33 4–7 linear 200 2.0 1.7 3.4 3.2 23.9 65.0 2.8 28 6–8 a) b) c) d) Fig. 4.

Careful TEM observation and diffraction pattern analysis revealed that the intermediate layer consists of the amorphous including extremely fine Al grains [2].
The deformed area inside the ridge consists of a bundle of squashed grains.
In contrast to that, the deformed area outside the ridge exhibited refined grain structure.
SEM observation found that fracture surface of the joint region inside the circular ridge exhibited relatively flat surface with a limited number of dimples.
Microstructure observation revealed that grain size was refined in Al matrix close to the welding interface.

Temperatures above 1100 °C are hot enough for significant grain growth, as well as dynamic recrystallization, if there is also sufficient strain [14,15].
These higher temperatures can also lead to intergranular crack formation along the austenite grain boundaries, as any applied strain is concentrated at the weakest (hottest) grain boundaries, found at the base of the depressions, and are fewer in number when the grain size is larger after growth is allowed to occur [16].

The crystal structures and grain size of the LSM phase derived from the LSM sol were studied as a function of the processing parameters.
If the ratio of citric acid to metal cations was kept at 2.5 and the weight ratio of citric acid to ethylene glycol varied to 1:2, 1:3 and 1:4, the grain size of the powders changed obviously.
As a result, when the ratio of citric acid to ethylene glycol was changed from 1:2 to 1:3 and to 1:4, the grain size of the fired LSM powder became smaller and the surface area of the powder became larger, which means more reaction activity.
The grain boundary of the substrate and film with small cracks can be seen clearly if the thickness was about 40nm (Fig.8b).
Acknowledgements This material is based upon work supported by the Department of Energy SECA Core Technology Program under Award Number DE-NT0006557 and Fundamental Research funds for the Central Universities.

The Young's modulus is set to a very small number at the nodes above the coherence temperature.
The stirring action makes the grains morphology of strip center region different from that of surface.
The effect of deformation on microstructure of as-cast strip (A): Simulation result of mesh deformation at coherence region, (B): schematic of stirring action in coherence region, (C) refined grain at as-cast strip center caused by stirring action.
One was completely split crack along the grain boundary shown on Fig.7 (B).
The other type of crack filled with squeezed metal around grain boundary, shown on Fig.7(C).

Therefore, an important and necessary step to the practical application of this process for hot rollers is to overlap a number of laser tracks to produce a continuous modified layer.
Eutectic carbides are precipitated at the grain boundaries (GBs) forming an interconnected network.
The influence of tempering could be neglected due to the improved tempering stability of the MZ resulted from the increased content of carbon and alloying element in the solid solution, refined grains [8, 9].
The high content of carbon and alloy elements in the high chrome steels gives rise to carbide segregation at the GBs and -2.4 -1.6 -0.8 0.0 0.8 1.6 2.4 250 300 350 400 450 500 550 Microhardness(HV) Distance from the center of beam(mm) OR=16.7% OR=33.3% OR=50% 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 350 400 450 500 550 600 650 700 750 Microhardness (HV) Distance from the surface (mm) Single track OR=16.7% OR=33.3% OR=50%-7 -6 -5 -4 -3 -2 -800 -700 -600 -500 -400 -300 -200 -100 OR=33.3% OR=50% OR=16.7% Potential Vs SCE(mV) Log values of current density(A/cm 2 ) As-received steel a coarse-grained microstructure by centrifugal casting.
The influence of tempering can be neglected due to the improved tempering stability of the melted zone arising from the increased content of carbon and alloying elements in the solid solution and refined grains

Therefore, it is convincible that even higher grain refinement, met in a nanocrystalline powder, could preserve good superconducting properties while improving mechanical properties and sintering characteristics.
In its seminal work Nakamori synthesized crystalline MgB2 (about 200 mm grain size) at high temperature (1173 K) and high pressure of hydrogen.
Some elevated background was visible in the XRD pattern, but the broadening of the peaks for β-MgH2 and MgO due to the small grain size (8 nm) can account for almost all of the elevated background.
The average grains size of the nanocrystalline MgB2 nucleating from the amorphous phase is less than 10 nm.
Since one ball can get on the travel to the magnet, then falls four times per one rotation one can estimate the frequency of impact events - f that scales simply as f = 4 N x RPM, where N is number of balls, and RPM refers to rotations-per-minute.

The mean austenite grain size corresponding to the austenitisation conditions was determined for each steel by applying ASTM E112 standard (Table 2).
Austenite grain size ( −d ) for given reheating conditions.
(2) where ε is the strain, ε& the strain rate, D the grain size, Qx the activation energy, T the absolute temperature, R=8.3145 Jmol-1K-1, and p, q and s are parameters.
Precipitates in austenite produce a delaying effect on recrystallisation kinetics, due to the fact that the pinning forces -which try to prevent grain boundary self-diffusion- increase considerably.
The mean particle diameter has been obtained measuring an average number of two hundred particles on each specimen.