Search results

Grain boundaries energy can be selected by a unit and a number of the most adjacent unit micro orientation combined to define, it can be described as: (5) Where Si and Sj are the i-th unit and its adjacent unit j orientation, contribution J for the adjacent cells on the grain boundary, it is proportional to the grain boundary energy, is Kroneckerδ functions, when ,it can be referred , when , it can be referred , the driving force of grain boundary migration is the reduction of the grain boundary energy.
The migration speed is: (7) The simulation results The evolution of the microstructure of the grain growth process Fig. 1 shows microstructure evolution process of the grain growth process simulation, simulation maximum orientation number Q = 32 is taken, simulation hexagon side length sets to 100, the simulation steps sets to 1000,in the photo, Fig. 1 (a)–(d) Correspond to the simulation step number 0 MCS, 250 MCS, 750 MCS and 1000 MCS of grain image, as can be seen from the graph, with the simulation time increased, grain grown, the average grain size increase.
In the grain growth process, smaller grain has constantly been adjacent size larger grain annex, curve boundary constantly tend to linear, reflecting the basic trend of grain growth.
Fig. 4 shows the change of the grain growth process in grain energy, it can be seen by the graph, in the initial moments of high grain energy, along with the grain recrystallization and the process of grain devouring growing up, the energy is continuously reduced and tends to be stable, to 300 MCS, grain energy almost no longer decreases and reaches a constant value.
Fig. 3 The relationship between the average grain size and the number of MCS steps Fig. 4 The relationship between the grain energy and the number of MCS steps Conclusions With the increase of simulation time, the grain grow older, the average grain size increases, and into a discrete distribution, to a certain extent, it reaches the maximum grain size, and no longer changes, stabilized.

Commodity grain is mainly from the cities and counties.
(2) Select the condensation point of the predetermined number, and the initial classification sample data
(2) The difference of the arable land and the number of the employed population The area of cultivated land is an important factor affecting the grain production capacity.
The first category is the grain production capacity in the worst area; the second category is the grain production capacity of the poor area; the third category is the grain production capacity of strong area; the fourth category is the grain production capacity of the strongest area
(2) Cluster analysis results show that the grain production capacity of Jilin Province with geographical location, number of each area, the area of cultivated land and agricultural population modernization level has great relevance.

FIRST-PRINCIPLES STUDIES ON GRAIN BOUNDARY ENERGIES OF [110] TILT GRAIN BOUNDARIES IN ALUMINUM Y.
It is important to accurately estimate the grain boundary energy in order to elucidate the atomic structure of the grain boundary.
Grain boundary energy.
The grain boundary energy is determined from the difference between the energy of a supercell containing the grain boundary and the energy of a supercell containing an equal number of atoms in the bulk environment, divided by the cross-section of the supercell.
Therefore, the grain boundary γ is given by SEE sg2 − =γ , (1) where Eg is the total energy of the supercell containing the grain boundary, Es is the total energy of an equal number of atoms in the bulk environment, and S is the cross-section of the supercell.

China nami_zhu@yahoo.cn Key words: lattice constant; cohesive energy; grain size; nanocrystallite Abstract.
Nm is the ion number in the fine crystallite with m layer ions out of origin ion.
Two limits are taken into account: ion distribution in a fine crystallite is close to spherical symmetric; the number of cation and the one of anion is approximately equal.
Thus, we can conclude that the lattice constant decreases with the reduction of the grain size for NaCl structure ionic crystallites.
For BCC structure metal crystallites, computed by the above method, obtained the dependence of rn and r1 on atom layer number m are shown in Fig.2(c) and 2(d).

This adds an additional factor of two to the number of symmetrically equivalent boundaries so that 2•2•122 symmetrically equivalent grain boundaries are generated from a single grain boundary trace.
Journal Title and Volume Number (to be inserted by the publisher) 3 Results Based on the EBSD data, the sample exhibited negligible grain orientation.
Journal Title and Volume Number (to be inserted by the publisher) 5 MRD Figure 3.
Boundaries that create a misorientation with the minimum number of dislocations are preferred and these are typically boundaries that are perpendicular to the Burgers vector of the dominant dislocation.
Acknowledgment This work was supported by the MRSEC Program of the National Science Foundation under award number DMR-0079996.

Gerasimov1,b* 1Perm National Research Polytechnic University, 29, Komsomolsky ave., Perm, Russian Federation acrocinc@mail.ru, bromagrizly@gmail.com Keywords: molecular dynamics, crystallization, grain boundary, grain boundary analysis, grain boundary energy, EAM, central symmetry parameter.
Therefore, particle method is used to simulate the formation of grain boundaries.
Berendsen thermostat suppresses fluctuations of the kinetic energy, so the sample canonical ensemble will have the discrepancy which decreases as the (where N is the number of particles in the ensemble).
The average number of particles in the calculation region becomes equal to 170 000 (in the ideal crystal lattice of copper this number of copper must be equal to 177 000), which gives 96% of real copper density; in the considered central region this number is not more than 106 000.
Dependencies of the number of atoms of different types as a function of time were built.

The Brandon criterion [13] was used to classify Σ3n boundaries, both as a length fraction and as a number fraction, with n≤3, i.e.
In a heavily twinned material, as a 'rule of thumb' the length to number ratio is close to 3:2 [14].
Although the relative number of Σ3s is less than their relative length, the opposite is true for Σ9 and Σ27 boundaries.
Proportions of Σ3, Σ9 and Σ27 boundaries as (a) length fraction and (b) number fraction for each specimen.
The rate of increase of Σ9 number fraction from the asreceived to the pre-treatment stage is greater than the accompanying rate of increase of Σ3 number fraction.

The typical rolling textures after deformation are not strong and a large number of low-angle grain boundaries are found.
The grain of as-cast copper ingot is visible to naked eyes except for fine grain area, and the grain size is at the level of millimeter.
Coarse grain can be transformed to fine gain, as shown in Fig. 2(b), small equiaxed grain with an average grain size of about 100μm is obtained.
The grain size is about 17.9μm.
The typical rolling textures after deformation is not strong and a large number of low-angle grain boundaries are found.

The effect of number of deposited layers on the grain size and surface morphology has been investigated using an atomic force microscope in contact mode.
The relation between the value of grain size and number of deposited layers is plotted in Fig. 2.
It can be observed that the grain size increases as the number of deposited BGT layers increase.
Figure 2: Variation of grain size with different number of deposited layers of BGT.
Using the same theory, the decrease in the surface roughness with number of deposited layers increment can be attributed to the gradual disappearance of the agglomerated grain regions as the number of deposited layers increase to appear as individual grains for four layers sample as it discussed earlier in Fig. 1.

To analyze compression deformation characteristics of coarse-grained soil under different moisture content and different grain compositions conditions, influence pattern of moisture content and grain compositions was researched through uniaxial compression test.
Table 1 Experiment of variable moisture content sample number M1 M2 M3 M4 M5 M6 moisture content (%) 0.69 2.22 4.43 6.31 8.60 10.32 dry density (g/cm3) 2.10 2.08 1.98 2.03 2.07 2.11 Table 2 Experiment of variable grain compositions number the occupation of the mass under a certain size among the whole mass (%) 60mm 40mm 20mm 10mm 5mm 2mm 0.075mm M1~6 100 79.1 46.7 30.8 20.7 12.3 2.9 N1 100 92 32 24 16 8 0 N2 100 92 84 76 68 60 10 N3 100 88 76 36 24 12 2 N4 100 100 80 60 40 20 5 N5 100 80 80 60 40 20 5 N6 100 88 48 36 24 12 4 N7 100 40 32 24 16 8 0 N8 100 80 60 40 30 20 5 Influenced Factors Analysis of Compression Deformation Select uniaxial consolidometer of Φ280 mm×230 mm and conduct creep test with gradation loading method of 50→100→200→400→800kPa according to the distributing character of the filling layer.
Through the study of grading analysis, mass percentage of soil sample’s certain grain takes up too much or too little, with N1, N2, N3, N6 and N7 containing more than 40% of certain grain and N4, N5 missing in another grain, resulting in a uneven grain size distribution.
Table 3 Testing parameters and results of variable grain compositions sample number N1 N2 N3 N4 N5 N6 N7 N8 dry density (g/cm3) 1.80 1.88 1.92 1.99 2.00 2.02 2.04 2.06 final deformation (mm) 13.56 11.77 9.32 7.56 5.80 5.07 4.13 3.93 Analysis on Compressive Deformation Characteristics After applying axial load, read number every 15 seconds in the first 15 minutes and then read once every 15 minutes until compressive deformation becomes stable. 14 groups of data with similar deformation characteristics were acquired.
Secondly, only considering influence of grain composition on compression deformation, the filler, with a good gradation and 70% coarse-grain partial contained, is recommended to be applied.