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Under wet conditions, porosities are observed spread inside the scale and the chromia grain size is smaller.
It is also observed that the chromia grain size tends to be smaller under wet conditions.
Fig.3 shows the mass change curves versus the number of cycles at 1100°C.
Fig. 3 Mass change versus the number cycles for SY 625 specimens after cyclic oxidation at 1100°C, in dry air and wet air with 7.5 vol.% H2O (8 l/h flow rate).
Under wet conditions, porosities are observed spread inside the scale and the chromia grain size is smaller.

Results show that after 80% deformation, the crystalline grains of the composite matrix plastically deformed in elongated shape to a certain direction as banded fiber structure.
It is found that after 80% deformation, the crystalline grains of the composite matrix plastically deformed in elongated shape to a certain direction as banded fiber structure arising from the matrix heavy plastic deformation of the Al2O3 dispersion strengthened copper matrix composites.
In addition, the disperse Al2O3 particles are pinning around dislocations to form high-density dislocation tangles and deformed sub-grains.
A large number of dislocations tangle around the fine Al2O3 dispersion particles.
The main roles of the additive yttrium lie in its purification to the crystalline grain boundaries of the copper matrix and yttrium oxide formed during the Cu-Al-Y alloy melting process dispersion strengthening to some extent.

(a) (c) (b) Fig. 2 SEM microstructures of the SiCw/AZ91 composite after compressed to the different strains of (a) 1 %, (b) 60 % and (c) 100 % Large numbers of twins are observed when compressed to the strains of 10 %, as shown in Fig. 4 (a).
Twins in the composite are broken severely and fine sub-grains are formed in the twin boundaries and twin intersections (as denoted A and B in Fig.5 (a)); and high-density dislocations are piled up in some sub-grains (e.g. grain C).
For AZ91 after compressed to the stain of 100 %, seen in Fig. 5 (b) and (c), sub-grains are formed at twin intersections (e.g. grain D).
New fine sub-grains are formed in twin boundaries and twin intersections in both the composite and alloy when compressed to the strain of 100 %.
(4) In the composite, recrystallized grains were nucleated at highly distorted places of twin boundaries and twin intersections.

The microstructure in semi-solid state consists of fine spheroidal solid grains surrounded by liquid.
The required spheroidal microstructure can be obtained by a number of routes.
To obtain a high solid fraction with homogeneous round recrystallised grains, a three step heating cycle is used [5].
The third step of the heating cycle breaks down unrecrystallised grains that assist a freezing flow (Fig. 2).
The RAP process was used with a three step heating cycle to obtain recrystallisation and hence small globular grains (≈100 µm) surrounded by a liquid matrix.

The characterization of Raman spectroscopy and X-ray diffraction (XRD) further confirms that the grain size of USCD film is down to the nanometer scale.
Murakami’s reagent attack WC grains and roughen the substrate surface.
After each deposition, the deposited MCD or NCD film is polished with both diamond grits (1μm) in order to eliminate the sharp edges of diamond grains.
It can be seen that the insert surface is covered by a continuous layer of fine-grained MCD film with diamond grains of~4–5μm in size.
It is also noted that the slight shift in wave number of diamond peak from 1332 cm-1 can be owing to the residual compressive stress in the film.

Strong adhesive bond at the interface will be achieved in the case of the hydrogen and a small number of covalent bonds formation when interacting the activators with mineral surface adsorption centers [16].
Grain compositions, porosity, swelling, bitumen content indexes and water resistance coefficients were defined.
Bitumen additive hydrophobizises the mineral powder grains surface.
Spherical porous grains are destroyed, the number of open and closed micro and macro pores, as well as micro cracks of hydrophilic vitreous particles are reduced, which also contributes to the improvement of the activated mineral powders technical properties.
This layer modifies the ash grains surface and changes its adsorption properties.

In the case of EFG wafers, which have large (typically 10-15 mm or greater) grains, samples from good and bad grains were cleaved using minority carrier diffusion length maps.
Briefly, Astropower sheet material was mapped with µ-XRF and transition metal clusters were found both at grain boundaries and inside the grains.
For example, at one location at the grain boundary, we found traces of iron precipitated along the grain boundary, and a large copper precipitate at the edge of the boundary.
Iron clusters were also found in a number of locations inside the grains; some of these clusters contained both copper and iron.
Baysix and EFG materials also contained metal precipitates, but the number of large precipitates and the average size of these precipitates were smaller, a direct consequence of these materials containing less transition metals.

The results of the relationship between grain size and properties of microalloyed steels containing Nb, V, Ti or Al show that [5-6], grain refinement is the only effective means to strengthen and toughen steel, and precipitation strengthening is also a major strengthening mechanism for microalloyed steels.
It was because the lower the deformation temperature, the deformed material was less likely to recrystallize, the austenite growth tends to decrease, the austenite grains were finer, and there were more grain boundaries in the large austenite grains at the high temperature finish rolling temperature, the nucleation rate of the new phase formed along the austenite boundary and the internal deformation zone increases, which favors the precipitation of ferrite and pearlite along the grain boundary and the crystal; in addition, the residence time of the sample in the high temperature zone was relatively short.
One reason was that the austenite grains are flattened, which increases the grain boundary area per unit volume and provides more nucleation sites for the new phase.
Another reason was that the deformation also causes an increase in the nucleation rate of the new phase per unit area on the austenite grain boundary surface; at the same time, a large number of deformation zones were formed inside the deformed austenite grains, and these deformation zones were also new phase nucleation sites.
It also leads to grain refinement of ferrite and pearlite.

The average grain size, found using the linear intercept method, was 3 mm.
The hysteresis loops for selected numbers of cycles were recorded in a disk memory.
Inconel 792-5A used in the present study is characterized by very coarse grain size.
Thus, only several grains in the volume of a specimen corresponding to the gauge length are present.
The number of cycles to fracture is reduced with increasing temperature except for temperature 800 °C (see Fig. 2).

Without taking care of that fact, the starting fully melted sample solidifies into a polycrystal which exhibits a diversity of grains.
SCN - 0.3wt% water (V=10 µm/s and G=30 °C/cm) Diameter : 10 mm Fig. 3 : Interface image during columnar growth showing a large number of grains with different dendrite morphologies.
Then increasing the booster heater temperature, all the small grains formed at the bottom of the crucible are melted but one (Fig. 4).
By decreasing the booster heater temperature, this last grain is then expanded laterally until it fills the whole section of the sample.
Direct observation, mainly from the top (Fig. 5a), is used to study the dynamical evolution of the dendritic pattern (primary spacing measurements, number of neighbors, competition between dendrites).