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Significant feature in silicon carbide crystal structure is its polytypism, which exhibits a number of different one-dimensional ordering sequences without any stoichiometric variation.
According to Ramsdell [20], the notation of these polytype consists of one number describing the number of layers (A, B or C-layer) associated with the unit cell, and a letter indicating the crystal system (cubic (C), hexagonal (H) or rhombohedral (R)).
Another hypothesis assumes that boron modifies the properties of grain boundaries by lowering the grain boundary energy.
Fig. 6 (b) shows a lattice fringe imaging of a near (111) grain boundary having no amorphous or crystalline intergranular/grain boundary phase [76].
It should be noted that epitaxial crystalline grain-boundary films were often formed on the (0 0 0 1) grain-boundary surface of the matrix -SiC grains.

The discontinuous electron density difference of phase interface Fe4N/a-Fe under the first order approximation results in the remarkable strengthening effect as well as the significant decrease in toughness and ductility, demonstrating the reason that nitrogen can cause cold shortness; as the electron density difference on AlN/γ-Fe, AlN/γ-Fe-C(Al) phase interface is very large and the continuous number of the phase interface is very small, the add of Al can hinder the growth of grain, as a result, the austenite grain is significantly refined and the removal of cold shortness caused by Fe4N can be achieved.
The Fe4N phase behaving as dispersion degree can distribute along grain boundary and prevent the movement of dislocation, resulting in the embrittlement of alloy.
The precipitation of AlN not only make the austenite grain refined, but also cause the decreasing in the content of free nitrogen in steel.
The covalent bond distribution on the (111) crystal plane of Fe4N (shown in Fig.1) is as follows: Fig.1 Atom arrangement on (111) crystal plane of Fe4N aN N Fec Fef , IB=1.5×2×2=6; , IC=1.5×4×1=6; The total covalent electron number of (111) crystal plane in Fe4N is.
If it is considered that the growth of recrystallization grain is connected to the continuity in interface electron density, the worse the continuity of phase interface, the more difficulty in the movement of phase interface, and the more difficulty in the growth of grain.

GSHP exhibited a better control in temperature in warehouse and grain heap.
The parameters of biological activity of grain were determined.
Currently, large warehouse is widely used in grain depot of China.
But due to its poor thermal insulation performance, the highest temperature in warehouse and grain heap can be as high as 30-35°C in summer, which results in serious breeding of a large number of pests and bacterial, which can affect the eating quality of rice seriously [2].
The total number of microorganisms The total number of microorganisms was determined by plate culture counting method [9].

Yu et al. [11] proposed a fine-grained data access control scheme.
The children of a node x are numbered from 1 to numx.
The function index(z) returns such a number associated with the child node z.
Waters: Attribute-Based Encryption for Fine-Grained Access Control of Encrypted Data.
Lou: Achieving Secure, Scalable, and Fine-grained Data Access Control in Cloud Computing.

After the drawing process, the dynamic recrystallization grain size in 60% of the cross-section area is less than 100 μm , and the grains get refined.
Happen recrystallization metal through internal high fault density induced recrystallization grain nucleation, a large number of dislocation disappear bring higher degree of softening, at the same time interior grain fully refined [2].
Setting initial grain to uniform 100 μm.
Dynamic Recrystallization Grain Size Changes.
Dynamic recrystallization volume fraction The number of node (percentage) （b） Dynamic recrystallization volume fraction The number of node (percentage) （a） Dynamic recrystallization volume fraction The number of node (percentage) （c） Fig.4 The grain size change in different reductions: (a)10%; (b)20%; (c)30% Figure 4 said great billet in pressing rate respectively by 10% (just happened dynamic recrystallization), 20% and 30% (heart department fully dynamic recrystallization) when the dynamic recrystallization grain size distribution, y-coordinate said has a certain dynamic recrystallization size node percentage.

The grains were aligned in the same direction.
It can be seen from Fig. 2(b) and Fig. 2(c) that, due to the effect of grain size, the increase of annealing temperature leads to grain growth, the ratio of surface grain to internal grain increases, the proportion of surface grain increases, and the growth of twins depends on the decrease of interfacial energy.
At the same time, in the thermal insulation stage of annealing, a small number of grains will swallow up the surrounding small grains and grow rapidly, resulting in secondary recrystallization and the phenomenon of uneven grains.
Influence of grain size on mechanical properties.
(b) (a) torn grain Surface torsional torn grain (d) (c) surface torsional Fig. 4.

According to Eq.3, the contact pressure of each effective abrasive Pi is related directly to the number of abrasives involved in machining.
Usually, there are a lot of effective abrasive grains in the working area, and the number of them may be thousands or even more.
Normally, the contact pressure of a single abrasive grain Pi is very small.
Once some abnormal larger grains are interfused in polishing process, the number of abrasive involved in machining will be decreased sharply.
Maybe only hundreds of abrasive grains or even less are still active.

Fatigue cracks in ultrafine-grained structure develop both in the regions of larger grains and also in the fine grained areas.
The average grain size in the fine grained areas is 3.3 ± 0.5 µm whereas in the large grain areas the grain size is 9.9 ± 4.5 µm.
The shift in number of cycles to failure is nearly two orders of magnitude.
Cracked grain boundaries in fine grained area. σa = 180 MPa, N = 1.5 x 103 cycles.
In the case of UFG alloy, the number of slip bands rapidly decreases with decreasing stress amplitude.

Introduction Nanocrystalline materials, which are structurally characterized by nanometer-sized grains with a large number of grain boundaries, have been found to exhibit many novel properties relative to their coarse-grained counterparts [1, 2].
The sample surface to be treated is impacted by a large number of flying balls over a short period of time.
Within initial coarse grains, multiple twins are formed and their density varies from grain to grain due to different crystallographic orientations of the grains.
Apparently, formation of these high-density nanoscale twins induces a large number of twin boundaries subdividing the original coarse grains into lamellar nanocrystallites with special crystallographic orientations.
The presence of a large number of twins and their intersections hinder dislocation activities, and more dislocations exist at twin boundaries across which small misorientations were induced.

A large number of slip bands can be clearly observed.
The data on αexp of each grain are classified into four groups based on the number of active slip planes: grains with one slip plane, double slip planes, triple slip planes, and no slip bands.
The numbers parenthesized indicate the quantity of each type of cracks.
However as the fatigue loading proceeds, TC cracks grow so dominantly that a large number of them are even found cutting through grain boundaries.
On the other hand, in Fig. 7(a), (d) the values of h and SB show at sharp increase at some cycle numbers corresponding to crack initiation.