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Partial ring cracks are a particular crack type when grinding with large-size and blunt diamond grains.
Median cracks will cease to form after the grain depth of cut is below the critical depth of cut [7].
Median cracks are the only crack type, which existed in a small number of local regions.
Since the specimens were fine chemical mechanical polished silicon wafers with a surface finish 0.3nm in Ra, and no surface and subsurface damage existed before single grain grinding, any possible damage was induced by single grain grinding.
The deep narrow valley was an embodiment of the subsurface cracks induced by single grain grinding.

Ultrafine grained (UFG) metals with grain sizes in the range of 10-1000 nm exhibit favorable mechanical properties including very high strength and ductility[7,8].
After 14h immersion, a number of cracks but no corrosion pits were observed on the surface of the HPT treated sample in Fig. 5c, while it can be seen that the corrosion pits enlarged and the corrosion products were dissolved on the surface of the as-cast samples in Fig. 5d.
Thus higher density of grain boundaries and the uniform redistribution of second-phase nanoparticles in the grain interiors would accelerate corrosion by forming more micro-electrochemical cells at the initial stage of corrosion between the second-phase nanoparticles and the matrix and at the grain boundaries.
However, as the second phase of the as-cast alloy mainly distributed along the grain boundaries, the pitting corrosion mainly occurred at grain boundaries; therefore the second phase came off grain boundaries after immersion for 14h (Fig. 5d). 4.
[9] Balyanov A, et al, Corrosion resistance of ultra fine-grained Ti, Scr.

The solid squares indicate the average grain size.
When all grains are sequenced from large to small, the diameters of grains at of 20% and 80% of all measured grains are marked by an upper and lower short bars at the given frequency.
Two short bars at the extreme of a straight line are the upper and lower average grain sizes at the frequency, where the upper one is obtained by ranking all grains measured from large to small and then determined at grain number fraction of 20% while the lower is achieved at the fraction of 80%.
Therefore, in order to evaluate the uniformity of microstructures, we introduce two new parameters of d(0.8) and d(0.2); the former is defined as the maximum average grain size at which the grain number fraction is 80% when all measured grains are sequenced from small to large and the latter is the minimum average grain size with the grains number fraction of 20% in the same sequencing operation.
The solid squares indicate the average grains size under different levels of B0. 50 60 70 80 0 20 40 60 80 100 120 140 Electronic flux density (A) Average grain size (Micrometer) 90 Average grain size 50 60 70 80 0 20 40 60 80 100 120 140 Electronic flux density (A) Average grain size (Micrometer) 90 Average grain size Fig. 6 The measured grain size in AZ31B alloys as a function of electric current.

Refining of aluminum matrix grain and second phase particles improves strength, stiffness and ductility.
In resent years, ultra-fine grains can be obtained by severe plastic deformation (SPD)[1-3].
By increasing the processing temperature, the number of fine particle was reduce (Fig.3 (b) and (c)).
However, matrix grain size was very fine because of uniform distribution of eutectic silicon.
These dimples would be caused by grain refinement of matrix.

Too much or too less of dopants (both Pr6O11 and TiO2) in the varistor cannot obtain regular shapes of ZnO grains, and the grain boundaries are neither clearly observed.
The results reveal that the Pr- and Ti-rich phases were distributed at grain boundaries, triple point junctions or embedded in ZnO grains, which is an inhibitor for ZnO grain growth.
The inhibitors for ZnO grain growth include the secondary phases PrTiO3 and Zn2TiO4, and the praseodymium ions segregated in the region of grain boundaries [8].
The increase of varistor voltage can be explained by the increase in the number of grain boundaries owing to the decrease of the average ZnO grain size [9].
This is attributed to the increase of the number of grain boundaries caused by decreasing average ZnO grain size.

"Chinese Says" food safety in fact, only including food grain, soybean and potato, is Grain Security.
The Contribution of Irrigation on Grain Security in China.
The Sown Area of Grain and Irrigation Area Situation.
In the course of the development of China's agriculture efficient water use techniques, these departments have a number of joint researches, joint implementation, making many high - level results effectively promoting the development of china's agriculture efficient water use.
Relevant state departments should open up grain prices, according to the law of the market economy, completely open up grain prices, and implement grain subsidy for low - income urban residents.

After this grain growth occurs resulting in large grains that meet up at the centre line.
(ii) Nucleation and growth of few grains ahead of the first set of recrystallised grains which grow into the grains with low deformation.
The two above events are illustrated in Figure 2 where grain area of selected grains 1-7’ undergoing growth is plotted against time.
Plot of grain area with time of selected grains in the compressed and tensile regions.
All the initial nuclei labelled 1-4, in Figure 3a were highly deformed and had a number of zero solutions, the arrowed location 4 in Figure 3a had no solution where a near (111) <110> oriented grain labelled as 4’ in Figure 3d nucleated and grew.

However, the increasing degree of grain number is not directly proportional to inputting voltage.
Grain refining is not obvious with inputting voltage further increasing when the grain size decreases to a certain extent.
Howerer , [5] , thereinto, is the grain number per unit volume.
So, the grain numbers per unit volume become more with cooling rate increasing.
In addition, if stopping stirring temperature is too high, the grains nucleated will regrow, too.

After welding, the grains grow obviously near the welding line (Fig. 1b, c).
A few NbCs are observed as distributed randonmly in grains or on grain boundaries of as-fabricated specimen (Fig. 2a).
Fine NbCs (~30 nm) are rare in the as-fabricated specimen (Fig. 4a), but their number density increases by welding (Fig. 4b) with further increase during service (Fig. 4c), while the coarse NbCs shows stablility with a size of 100~300 nm (Fig. 5).
With long-term service in power plants, the number density of fine NbCs further increases, with no significant difference between fire side and steam side.
And HAZ is more brittle than matrix, which is caused by the a-Fe phase and coarse grain.

If the thermal expansion coefficients and elastic modulus of Ni base alloy and ceramic grain are different, there will be thermal stresses between grain and matrix in thermosyphon.
Ni base alloy ceramic composite coating is a mechanic disordered composite [2], a large number of ceramic grains are distributed in ductile matrix.
Because the thermal expansion coefficients and elastic modulus of Ni base alloy and ceramic grains are different, there will be thermal stresses in both grains and matrix in thermosyphon process.
The volume fraction of ceramic grains is f.
We can have the average stress in ceramic grain by the same method