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Some particles and coarse lamellas paralleling to each other distribute at grain boundaries and within grains in the initial billet, shown in Fig. 3(a) and (c).
A great number of lamellas and square or cubic-shape particles precipitate on the α-mg matrix after isothermal forging process.
The grains size remains unchanging during isothermal forging process, which indicates the isothermal forging process does not have an obvious effect on refinement of grains.
The average grain size is 8μm after isothermal forging process.
(2)A large number of lamellas and particles distribute on the matrix after isothermal forging process.

In contrast, the laser-remelted nanostructured coating composed of fine equiaxed grains (Fig. 3d).
Due to the rapid solidification of laser remelting process, there are remained some nanoparticles in the remelted zone because of an insufficient time for grains growth.
Plasma-sprayed ceramic coatings have high porosity and the number of pores can reduce the coating thermal conductivity and improve the coating insulation effect [12, 13].
The nanostructured coating owns more fine grains and number of grain boundaries than the conventional one.
Due to fine grains and number of grain boundaries, the nanostructured ceramic coating has higher thermal barrier effect than the conventional one.

Figure 1 and 2 show that the grains and grain boundaries in conventional casting are rough, but in directional casting method are fine.
SEM observation showed that the crack initiation is from grain boundary (fig.3), EDS analysis show that continues phases in grain boundary is Al-Cu rich phase (fig.4).
Cu-riche phases formed in grain boundary during the solidification (fig.4).
In conventional casting, the solidification time for segregation is sufficient and the grain boundaries will be coarse, homogenization process to dissolve grain boundary's phases take a long time and surface oxidation occur, also grain growth will occur during long time homogenization.
Vol. 257 (1998), p 100 [3] J.R Davis et al: ASM specially Hand book, (Aluminum and Aluminum Alloys) (1993). p. 121147 [4] Alex Cho, Richmond: (1995) Patent number: 5,198,045 [5] A.Joshi,: Mechanical Institute of Technology I.I.T, Bombay, (2002) [6] Z.

Ferrite forms a grid at the grain boundaries.
Inside one grain surrounded by a grid of ferrite, several colonies of perlite are visible.
In ferrite, precipitation is observed, especially along the grain boundaries.
There are ferrite grains with uneven boundaries and precipitations along the boundaries.
The result is a large number of small inclusions that do not significantly affect the mechanical properties of steel.

Polycrystalline yttria (Y2O3) has a number of outstanding characteristics such as; low chemical reactivity, refractory character, low thermal expansion coefficient (~7.3 x 10-6 /°C) and a high melting point (around 2410 °C) [2].
Although the size of the starting TiO2 nanopowder was <25 nm, final grains showed a significant grain growth.
These nano-sized grains were present at grain boundaries, triple junctions and partially in the Y2O3 grain interiors.
Furthermore, ZrO2 grains trapped inside the matrix are believed to have a role in dividing a grain size into more finer sized particles by forming sub-grain boundaries [6].
The results support the idea that precipitates at boundaries and triple junctions pinned the boundaries and those inside the grains have a role in dividing a grain size into more finer sized particles by forming sub-grain boundaries.

The average grain sizes were calculated using the Scherrer method with a shape factor of 0.9.
The gradual decrease in discharge capacity with number of cycles corresponds to the decrease in peak intensity as a result of incomplete redox reactions.
This may be related to the fact that this material possessed the greatest average grain size and it may be possible that during the cycling process, the larger grains were broken down to yield an overall increase in the surface area that is in contact with the electrolyte.
Further work will be performed to see if this might be caused by lithium ions segregating at the grain boundaries in some way.
Both of these factors influence the average grain size of the material, and it may well be this that is the dominant factor.

Fig.3 shows the grain structures of bulk CoSb3 and CexCo4Sb12 observed.
It shows that the grain sizes remained in the nanometer range of 100~500nm.
Fig.5 shows that for the samples with x=0.1,0.3 and 0.5 the site occupancy number of Ce atoms in the unit cell are 0, which indicates that the rare earth Ce atoms do not entered the voids.
While for the samples with x=0.7, 0.9 and 1.0 the site occupancy number of Ce atoms in the unit cell (Co4Sb12) are 0.053, 0.1555 and 0.1355.
Fig.5 The schematic of the Ce content occupating in the voids of Co4Sb12 Ce content Ce content Ce occupying number Conclusions (1) CoSb3 and CexCo4Sb12 sintered at the temperature 650℃ have the same average crystal grain size observed by TEM, therefore rare earth element Ce does not change their crystal grain sizes so that the effect of crystal size on thermal conductivity should be on the same level

It was found that the iron-intermetallic particles decreased in size with numbers of turns.
Fig. 3(a-d) Wear track widths of worn surfaces and (e) wear volume loss vs. number of turns.
The results show the wear volume loss decreases with increasing numbers of turns.
The enhancement of wear resistance is mostly described by grain refinement of materials after SPD processing.
Yoon, H.S.Kim, Wear properties of ECAP-processed ultrafine grained Al-Cu alloys, Mater.

The presence of a SiNx coverage layer at the grain boundaries and its constant thickness in the 3rd region have been confirmed from optical and electrical measurements [7] and [8].
The coverage represents the ratio between the number of segregated Si atoms on the NbN crystallite surface and the number of sites of Nb atoms on the NbN crystallite surface.
In the case of films deposited at 910 K, the average grain size (obtained from XRD measurements) decreases from 25 nm at 1.5 at.% Si to 6 nm at 5.7 at.% Si.
In fact, with the increase of the deposition temperature, for the same mean value of the grain size, the length/width ratio of the crystallite increases significantly.
The NbN crystallites exhibit elongation in the growth direction in all deposited films, even in the films having the smallest mean grain size of about 2 nm.

It is proved that in this case the effect of ultra-low doses of surfactants is to reduce the number of open pores in cement stone and concrete.
In addition, modern construction requires a number of engineering problems to maintain the efficiency and functionality of existing buildings, structures, road infrastructure, which is associated with increased physical depreciation of fixed assets.
The conducted research has strong properties of the influence of surfactant microdoses on the quality and porosity of fine-grained concrete, which are to increase the strength and decrease the porosity.
This indicates the possibility of targeted regulation of the formation of a strong structure of fine-grained concrete by using surfactants in ultra-low doses at elevated temperatures and humidity of its curing medium.
[11] А Shyshkina, A.Shyshkin Fine-Grained Concrete for Repair and Restoration of Building Structures Materials Science Forum Submitted. 1038, (2021) 317-322.