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As the image intensity in the Z-contrast is approximately proportional to the square of the atomic number, STEM technique is especially well suited for understanding the role of heavy impurities in grain boundaries composed of much lighter ions.
Fig.1 shows a Z-contrast image of the Y-doped 31 grain boundary in Al2O3.
Z-contrast STEM image of Y-doped  31 [0001] tilt grain boundary in alumina.
According to the first principles calculations, the presence of Y at the 7-membered rings was found to increases the number of bonds, and the bond strength was increased due to the higher covalency of the Y-O bonds [3].
This should result in a much stronger grain boundary, which explains why the Y-doped grain boundaries can have such a large increase to creep resistance despite the fact that only a small amount of Y is present [4].

of Resources and Environment, Sichuan Agricultural University 46 Xinkang Road, Ya'an 625014, PR China; 2 College of Resources and Environment, Sichuan Agricultural University 46 Xinkang Road, Ya'an 625014, PR China; 3 College of Resources and Environment, Sichuan Agricultural University 46 Xinkang Road, Ya'an 625014, PR China; 4-6 College of Resources and Environment, Sichuan Agricultural University 46 Xinkang Road, Ya'an 625014, PR China; aemail: wanglei198626@163.com , bemail :wuj1962@163.com, cemail: Shuzhen0827@163.com , demail: 16422272 @ qq.com eemail: wl8579086@163.com , femail: 804869246 @ qq.com Keywords: Biogas slurry; wheat; yield; heavy metal content; Abstract: In this paper, throng studying effect of biogas slurry of different fertilizer rates on wheat yield and some biological traits, found that environmental conditions in the purple, biogas slurry application rate was 3500kg/667m2, wheat yield was maximum; And heavy metals Content in wheat grain
Table 4 data showed that the treatment was no significant difference between the grain weight, but plant height and panicle number and grain yield of acres were close (correlation coefficient were significant or highly significant), suggesting that biogas slurry supply adequate nutrient, the proportion of coordination, promoting the growth of crops and form of Spike long, thus wheat get a higher yield, Biogas slurry application rate is too high, but also inhibited the production of wheat. 3.2 Effect Of different treatments on heavy metals content in wheat grain Fig. 1 showed that heavy metals Content in wheat grain would increase with the increasing of biogas slurry application rate; When the slurry application rate was in 1500 ~ 4500kg/666.7m2 (for treatment 5 - treatment 9), Wheat grain Pb, Cd content and conventional chemical fertilizer treatment was not significant (P> 0.05); When the slurry application rate was in 5000kg/666.7m2, Wheat grain Pb, Cd were significantly higher than
Wheat grain Cr content was significantly lower than conventional chemical treatment (P <0.05).When the slurry application rate controled in the range of 1500 ~ 3500kg/666.7m2, compared with conventional chemical treatment, the application of biogas slurry did not cause the increase of heavy metals in wheat grain.
When the slurry application rate was high (≥ 4500 kg/666.7m2), the application of biogas slurry led to the rise of heavy metal content of wheat grain than conventional chemical treatment and mixed fertilizer treatment.But compared to the limits of the “Contaminants in Food”(GB2762-2005), the slurry treatment of wheat grain Pb, Cd, Cr, As, Hg content were lower than the corresponding limits of pollutants (including As, Hg were not detected),showing biogas slurry agricultural would not cause food heavy metal pollution, Wheat planted was in line with food hygiene standards. 4 Conclusions The slurry contains a comprehensive nutrient and rich organic substances, which has the speed slow shrugging characteristics of exploiting, soil improvement.This study suggests that in the dry system, Sichuan neutral purple soil environmental conditions, in the whole growth period, it can supply the nutrients needed for growth of wheat, so as to promote wheat growth and development, and improve the biological
yield and biological Treatments Grain yield (kg/hm2) 1000-grain weight(g) Plant height (cm) spike numbers （ten thousand/hm2） 1（ck1） 4882.67 63.82 100.33 300 2（ck2） 6569.00 61.36 96.83 363 3（ck3） 5731.33 62.90 94.56 341 4（ck4） 7801.00 59.50 97.17 314 5 7357.50 65.02 89.50 292 6 8194.50 63.28 89.00 352 7 7078.00 66.37 87.83 317 8 7312.50 65.67 98.50 283 9 5738.33 64.67 96.67 327 Fig. 1 References [1] Turner XuZhaofei, ZhangHuiye, ZhangDingyi.Wheat Quality and Its Improvement[M],Beijing.

Chromium diffusion along the grain boundaries is more favorable.
The carbide formation reveals that the distance between carbides increases and the number of grains in the steel decreases as carbides grow.
Fujibayashi et al. also observed cavities with dimensions of less than 5 µm in small grains [5].
This progression can happen either inside the grains or at the grain boundaries, depending on the microstructure and stress state of the material.
In this study, Fig. 5b confirmed that cavities located near grain boundaries were due to high load, under which, the stress concentrated on the grain boundaries, leading to the formation of cavities near these positions.

The method provides the greatest number of information when testing the stents' surface and it is well applicable for the analysis of surface alterations caused by different specific tests, e.g. fatigue test.
The most frequent surface failures of the coronary stents before expansion: a) small holes, b) inclusions, c) slip lines, d) failures caused by the mechanical finishing After balloon expansion the number of surface failures is increased, in strut bends, when the material has had bigger use, grains slip, slip lines and grain boundaries occur.
The reason could be that the stress was rather concentrated at grain boundaries compared to the inner part, and the grains were better deformed there [4].
Presence of slip lines and grain boundaries mainly occurred in the strut bends.
Some grains were also observed on the surface.

The finite element mesh adopted in this study is shown in Fig. 1 (b) using CPE4 unit with number of cells and notes of 1298 and 4069 respectively.
Fig .2 Stresses cloud of crack tip for grains with different single orientation.
Fig .4 Stress clouds of crack tip for grains with different combined textures.
Fig. 6 CTOD of crack tip for grains with single (a) and combined (b) textures.
Fig. 7 J-integral of crack tip for grains with single and combined textures.

Both grains are α-Mg grains.
For the convenience of later description, this larger grain is called α1-Mg, smaller grain is called α2-Mg.
Due to the long growth time, the grain size is large.
These nuclei form large number of small size α2-Mg grains under the effect of rapid cooling.
With the enhancement of pressure, the number of bright white phase on LPSO structure increases gradually.

The refinement of original grains was observed.
Number of passes are applied to the specimen resulting in a variation of crystallographic during the procedure by the strain accumulation [2-7].
Ferrite content was estimated terms of extended ferrite number (EFN) using Fischer ferrite scope.
There is significant reduction in the grain size.
The initial average grain size was 15.4 µm and after ECAP the grain size is 11.2 µm. 25µm 25µm a b Fig.3.

Both grain boundary energy and stored energy are taken into account in the calculations.
Moreover, relations for grain boundary energy and mobility have to be used.
The structure of grains is defined by a set of vertices (triple points) with positions rk where k=1,..., N (N is the number of vertices in a model sample).
Each (sub)grain has a homogeneous structure and is characterized by its orientation gi and SE value Ei.
Basing on experimental observations [9,10], it was proposed that a grain boundary can move only if the SE difference between two neighboring grains is higher than some critical value ∆E (called the SE threshold).

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Large grains at surface of chill cast thin plate.
In isothermal coarsening of a simulated 5160 seconds, a number of pinching-off events were found in the sample with the slightly more open structure.
In any of the foregoing cases, a number of ways may be imagined as to how the dendrite structure evolves.
Spherical grains are seen.

Annealing at higher temperatures results in grain growth.
However in some cases, the grain growth was retarded [7] whereas in other was enhanced [8].
The first micro-grained material was obtained by a conventional plastic forming, whereas the nano-grained via HE.
This recrystallization has a discontinuous character with subgrains at the primary grain boundaries and in the most deformed areas inside primary grains.
TEM images of austenitic steel 316 LVM in as-received state and annealed at 800°C/1h a) and after HE and annealing at 800°C b), numbers indicate the boundary misorientations in degrees a) b) Fig. 7.