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A number of factors such as the deformation history, microstructure stability, corrosion, stresses, creep behaviour and composition of scale play a important role in the life extension of highresistant steels [4,5].
The critical concentration of solute metal providing the formation of a protective scale during selective oxidation decreases with decreasing alloy grain size.
It is a result of fast diffusion along the grain boundaries, dislocations, martensitic laths, etc.

To develop grain boundaries of the samples after polishing, ion beam etching was carried out on TM4000 unit.
Nagata, 2015 IEEE International Magnetics Conference, INTERMAG 2015, Magnetic properties and microstructure of high (BH)max Nd-Fe-B sintered magnet with grain boundary diffusion treatment, Beijing, 2015
Article number 1017621

In fact, the horizontal rotary-disc-type precision seed-metering[5-7] can meet the technical requirement of single seed in one plant-opening to some extent, but some problems such as seeds damaged, replanted or leaking to be planted are always occurred so that it is difficult to meet the requirement of accurate planting and plant number per area because both methods of cleaning redundant planting and seed charge are achieved by mechanic device.
If the distance is too long, the belt moving speed must also be fast so that the transportation speed of seeds could meet the planting speed, which is disadvantage to fill the seed into the scoop; on the contrary, if the distance is too short, the probability of repeatedly filling seed into spoon will sharply decrease because the stock between both seed-spoons is too few[6].Given that the probability of filling seed into scoop is denoted as p(a) which is slipped along the top of seed-scoop, the probability p(λ) of secondly filling seed into the seed-scoop is: (5) 3 Experiment and result 3.1 Experimental method The Xianyu 335 corn seed is chosen, the experimental method is established according to the requirement of GB6973-86《single grain planter (precision) test method》,250 seeds are measured for each test, and each test is repeated three times[10].
It can be seen by combination of above test results that the designed precision seed-metering owns good performance for high or low planting speed, such as high single seed plant rate, low seed damaged rate, and the integrated performance achieve the best when the belt speed is 1.05 m/s. 4 Conclusions 1) The optimal size of seed-scoop is 8mmX12mm which may achieve the single seed plant rate 98.6%, multi-seed rate 0.48%, leakage seed rate 1.78% and seed damaged rate 0.05% 2) The belt type of the precision seed-metering owns good operational character such as the single seed plant rate 98.6%, multi-seed rate 6.3% ,leakage plant rate 0.8%, damage seed rate 0.05%. 3) Good adaptability for high or low operating speed, which meets the working requirement for different operating conditions, and the best planting speed is 1.05m/s. 4) Simple structure which can be used for different grains by changing the seed scoop; even make seeds and fertilizer to plant at meantime by adding the fertilizer-spoon

Ding studied grinding characteristics of K-type carbide with different grain sizes[3].
The surface of wheel used was observed by optical 3D microscope system with beyond depth of field (Keyence VHX-1000), and measured the number of grits per unit area by 100 times, just as Fig.6 shown, which is fluctuated in the range of 15~45, and it is equal to 26.3 by statistics.
Reference [1] LU Q Z, ZHANG F R, YU L X, in: The condition and trend of Ti(C,N) cermet[J],, submitted to Journal of Wuhan Institute of Science and Technology, China, 15(5):43-46 (2002) [2] Gui Jicai, in: Research on ELID grinding mechanism and cutting performance of Nano cemented carbide[J], submitted to Harbin Institute of Technology,China (2009) [3] DING C S, ZHAO Y J, DING Y L et al, in: Grinding performances on cemented carbides containing different sizes of grain[J], submitted to Diamond & Abrasives Engineering, China, (05):67-70 (2009)

The creep activation energy observed in this study is close to those of high temperature alloys [17, 18], but smaller than that of grain growth at 850~950 ºC [20] and that of Ni diffusion in CrMnFeCoNi high entropy alloy [21].
With the increase of stress, the number and mobility of thermal vacancies increased, causing more visible large voids.
Lu, Grain growth and the Hall–Petch relationship in a high-entropy FeCrNiCoMn alloy, Scripta Materialia 68 (2013) 526–529

PBX is a kind of highly grain-filled composites being comprised of explosive grains as dispersing phases and high polymer binders as continuous phases.
JOB-9003 specimens machined from same cylinder are all φ20mm*30mm sized [3] and the number is 28 for being divided into 7 sets each of which includes 4 specimens.

C15 case-hardening steel was used as a basic material for the investigation and carbide powders (WC, TaC and NbC) were used for the dispersion. [1,2,4] The following parameters were determined as variables: ♦ the scanning velocity of laser :300 … 700 [mm/min] and ♦ the grain-dosing: 1 … 3.25 g/min. 2.2 Wear experiment in case of surface dispersed samples There is no mature, unified method to determine wear resistance as an absolute number, such as tensile strenght.
Parameters of the experiments: Cutting paper used for metallographic samples, SiC grained, size 230x280 mm, sign P180, for dry grinding.

In this way, many common thermal spraying problems can be effectively reduced and eliminated, like oxidation, phase change, ingredients change, grain growth[7,8].
This is due to in the coating deposition process the not completely deformed grain are covering and supporting and the pore remained.
It is showed in Fig. 3 (b) that the corrosion current coating and TA2 titanium alloy TiAl alloy fluctuates a lot and the number eventually become stable.

The results of property improvement mainly depend on the effect of grain size refinement.
Most of the cracks generate along grain boundaries and present obvious intergranular cracking characteristics.
Acknowledgement The authors gratefully thank the financial support of the National Natural Science Foundation of China under the granted number of 50375096.

Its average molecular number was about 1600 and the melting point was 180-210°C.
The apparent mean grain size (L) of the β-SiC crystalline phase present in the samples was calculated from the width (D) of the (111) diffraction peak at mid-height, according to the following Eq. 1.
Fig.2 XPS patterns of SiC-2 fiber Fig.3 FT-IR spectra of the fibers Fig.4 XRD patterns of the fibers Table 3 The size of β-SiC crystallite grain in different fibers Fibers SiC-2 SiC-1 SiC NL-202[5,6] L111(nm) 2.8 2.6 1.7 2.1 It can be observed that the crystalline size of SiC-1 and SiC-2 fibers is bigger than that of SiC fibers and it suggests that the crystallinity of CVC SiC fibers is better than the traditional SiC fibers.