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The 2D-peak is the sum of double and triple resonances, and the amplitude ratio I2D/IG can establish the number of layers in a graphene sample.
The ratio of ID/IG has been empirically characterised as a method to obtain the average crystallite size, La of nanocrystalline graphite and graphene, since the amplitude of the D-peak increases with a higher number of grain boundaries [18].
Previous work shows that graphene growth is generally non-epitaxial, with graphene grains observed to cross over underlying Cu grains [23].
High-strength chemical-vapor–deposited graphene and grain boundaries.
Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition.

Based on the microscopic observations, the cleavage initiation site was not influenced by the grain size of the material.
This represents a revolutionary advance in characterizing the toughness in the transition region, since it requires only a small number of relatively small specimens to establish the ductile-to-brittle transition curve of the fracture toughness.
The ASTM E 1921 master curve method provides the concept that the size effects for the cleavage fracture toughness in the transition region may be predictable by the probabilistic nature of the brittle fracture if there are a statistically meaningful number of data points.
Figure 9 shows that the cleavage initiation distance is not influenced by the grain size.
Table 3 Microstructural characteristics of materials having different grain sizes.

For HT1 specimens, there exist a large number of eutectic phases in both grains and grain boundaries.
Both γ′/γ eutectic and MC type carbide are observed inside the grain and at the grain boundary of HT1 specimens, however, a small amount of M23C6 type carbide distributed on the grain boundary.
In HT2 specimens, only MC type carbide is found inside the grain and at the grain boundaries.
It is also found that a small amount of the M23C6 carbide at the grain boundaries.
Carbides insided the grain and along the grain boundary are covered with γ′ film, which increases the mechanical strength of the alloy.

They have high corrosion resistance in a number of liquid media, are resistant to intergranular corrosion after welding heating, relatively little embrittlement as a result of prolonged exposure to high temperatures and can be used as a heat-resistant material at temperatures of ~ 600 °C [1, 2].
Characteristics of bellows N Bellows brand Flaring pressure, [МPа] Metal thickness, [mm] Number of layers Number of corrugations Welding current, [А] Welding speed, [mm/s] Argon consumption, [lpm] 1 NS 80-2-0.24×3 1.4 0.25 3 2 17 16.4 14 – 15 2 NS 92-3-0.24×3 1.2 0.25 3 3 17 16.4 14 – 15 3 NS 106-2-0.24×3 1.0 0.25 3 2 17 16.4 14 – 15 The process of manufacturing bellows is as follows: material in rolls weighing from 15 to 50 kg is fed to the cutting area, where it is cut into cards of appropriate sizes using guillotine shears.
Influence of welding current (a) and welding speed (b) on the value of the fracture elongation: 1 – 304L/2B; 2 – 316L/AB Since fine grains tend to increase the yield strength and improve the deformability of the metal, and also facilitate stress relaxation, in the heat-affected zone using the secant method, the average diameters of austenite grains were estimated.
The average grain diameter in the HAZ was 0.155–0.182 μm.
The grain score for samples is 6–7 points for HAZ, 7 points – for BM.

Since this clustering structure was caused by the exchange coupling among a number of grains, the small isolated clusters are due to the significant reduction of the strong exchange coupling among these grains
AFM observation indicates that annealing remarkably affects the grain size and the average roughness Ra. the average roughness Ra is 1.685, and the grain size is 42.481nm.
With the increasing of annealing temperature, the grain size decreases.
The grain size is 36.77nm when the annealing temperature is 300˚C.
The grain size has the minimum value of 27.969nm.

But only limited number of fundamentally inclined papers have been published on the erosion of ceramic-metal composites [1-3,5,8].
Moreover, many grains in the crater surroundings are displaced that accumulates the additive grain boundary strain.
If bond between grain and matrix and/or grain and grain is weak, intergranular cracks develop enough easily to propagate for a relatively long distance from the center of crater by brittle manner (Figure 10b).
In addition, there are a lot of coalescences grains and grain - grain interfacial energy may be twice greater than that of grain-binder energy.
The undamaged grains can be seen in the center of impact crater.

Each layer possesses different degree of hydrogenation and differs in number of defects and their location.
According to equations (2)-(4), electron scattering at dislocations and crystal grains causes the alteration of σхx , σyy values along the depth of a metal layer and with the change of temperature [8].
For instance, it leads to a significant alteration of N [2] and the number of hydrated titanium atoms.
The irradiation with the energy density of 12 J/сm2 leads to formation of a grained structure with the average size of ~5 µm and generation of folds that are oriented in different directions and envelope several grains.
This confirms the validity of formulas number 2 and 3.

Surface morphology and grain growth was observed using scanning electron microscopy (SEM).
Trend of volumetric strain in crystal structure and porosity of pellets are shown with variation of sintering temperature where n is number of formula units in BFO hexagonal unit, M is molecular mass of one formula unit, V is volume of unit cell and NA is Avogadro’s number.
Increase in temperature has affected the grain size and morphology.
According to Koops model, the effect of grain boundaries is prevailing in low frequency range.
Grain growth and melt like behavior was observed from SEM micrographs.

After a preliminary tensile test analysis, axial high frequency fatigue tests have been carried out at room temperature on specimen cut out from the suspension arm to determine the Wöhler curve and the number of cycles to failure.
After polishing, to discriminate the different crystals and eutectic phase, the samples were etched using an acid solution, made of 66% HCl, 33% HNO3 and 1% HF for 15 s to reveal the grains.
As can be seen in Fig. 1 the microstructure of all samples presents a globular non-dendritic structure, basically constituted by two phases: primary αAl grains (white areas) and by a Si-based eutectic phase (grey areas) with very fine structure among the globular grains with no indication of acicular phases was observed.
It was detected that apart from α-Al grain there are the presence of some other phases: α (AlFeMnSi) and a brittle phase belong to the intermetallic compound, Mg2Si.
Then, the Brinell hardness number (BHN) was calculated by dividing the load applied by the surface area of the indentation.

Fig. 4 Average Grain Size of Primary Silicon with Different Static Duration at 800°C Fig. 3 Volume Fraction of Primary Silicon Phase with Different Static Duration at 800°C As shown in Fig.3, the volume fraction of primary silicon phase of the untreated sample is about 28.34%, and the primary crystal silicon in the structure by direct casting is reduced by 18.56% by EPM; after standing for 5mins, the number of primary crystal silicon is increased in a certain degree; after standing for 15mins, the volume fraction is increased continuously by about 26.05%, which is close to that of the untreated sample.
Fig.6 Average Grain Size of Primary Silicon with Different Static Duration at 900°C Fig.5 Volume Fraction of Primary Silicon Phase with Different Static Duration at 900°C 2.3 The effect of holding time on alloy solidification structure at 1000°C.
Fig.7 Volume Fraction of Primary Silicon Phase with Different Static Duration at 1000℃ Fig.8 Average Grain Size of Primary Silicon with Different Static Duration at 1000℃ As shown in Fig.7, the volume fraction of the untreated sample at 1000℃ is 25.37%, but it is reduced by 16.52% in the structure by direct casting on EPM; after standing for 5mins, the number of primary crystal Si is increased in a certain degree; after standing for 15mins, the volume fraction is increased continuously by about 24.07%, which is the closest to that of the untreated sample.
At the same time, the refinement of primary Si phase is much better in (c) than in (a) and (b), which fully illustrates high-temperature pouring can also refine the grain and improve the effect of grain morphology. 2.5 The hardness of the sample.
The solubility of smaller silicon clusters is increased in the melt and the nucleation cores of coarse silicon phase in the structure are reduced in the number to improve the uniformity of the melt composition, therefore, the primary silicon phase is fine and uniform in the alloy solidification structure by EPM.