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For wrought magnesium alloys high-quality billets with fine grains and low segregation is critical.
However, the defects that the general magnesium alloys are prone to engender are more serious in AZ91 alloy due to its large number of low-melting point compound in the grain boundaries.
It is obvious that crystal grain is greatly refined and dendrites are degenerated owing to the effect of electromagnetic field.
Because of agitation behavior in the melt caused by Lorentz force, the dendrite crystal was detached by the strong convection in the molten melt, which, in turn, led to homogeneousness and refinement of the crystal grain.

The average grain size d of (Ni0.5Zn0.5)0.5Co0.5Fe2O4 ferrite is around ~ 35 nm.
This is estimated by means of the Scherrer formula d = kλ/βcosθ, where d is the average grain size, k is a constant (shape factor ~ 0.9), β is the full width at half maximum of the peaks, and λ is the wavelength of Cu-Kα radiation.
The grain sizes of the specimen are around ~ 40 nm, which was consistent with XRD analysis results.
If zinc ion (Zn2+) concentration further decreases with the increase of the Co2+ ion concentration, the change in concentration of Co2+ ions increase the number of Fe3+ ions at the A sites.
Conclusions To summarize, we have prepared nanocrystalline (Ni0.5Zn0.5)1-xCoxFe2O4 ferrite with a nanometer-scale grain size using a spraying-coprecipitation process.

After annealing at 200-500 °C, the ultra-thin ZnO seed layers show enhanced intensity of (002) peaks along with an increase in grain size and the crystallinity of ultra-thin ZnO seed layers was effectively improved by supplying sufficient thermal energy of the annealing process as expected.
After annealing process, it can be seen that the grain size becomes larger than the as-deposited ultra-thin ZnO seeds layer due to the improved crystallinity of the seed layer.
The annealing treatment would integrate small grains to form larger ones, which will reduce the number of the nucleation sites of ZnO NRs.
However, the ZnO NRs grown on ultra-thin ZnO seed layer with 400 °C annealing temperature had high aspect ratio which resulted in the seed grains to grow up when they were annealed at a high temperature, which offers a larger density and smaller diameter of ZnO NRs.

To implement this method, a number of installations have been developed that make it possible to strengthen parts of various complex shapes, including internal surfaces [16-18].
Microstructure of the sample surface after annealing: a - magnification х 100; b - magnification х 1000 After heat treatment (annealing), the hardening intermetallic γ'- phase (Ni3Al, Ti) practically completely dissolved in the solid solution, and its residues have a chaotic distribution over the grain volume.
Microstructure of the sample surface after SPD: a - magnification х 100; b - magnification х 1000 After SPD, the carbides are isolated in the microstructure of the material, and the redistribution of the hardening intermetallic phase is observed most of which was released near the grain boundaries.
Microstructure of the chip after the SPD with magnification х 220 Conclusion After heat treatment (annealing), the hardening intermetallic γ'-phase (Ni3Al, Ti) practically completely dissolved in the solid solution, and its residues have a chaotic distribution over the grain volume.
After SPD, the carbides are isolated in the microstructure of the material, and the redistribution of the hardening intermetallic phase is observed, most of which was released near the grain boundaries.

The Mg and Mg-based alloys with a nanocrystalline/ amorphous structure have been well known possessing superior hydrogen storage kinetics in the light of the high surface to volume ratios and the presence of large number of grain boundaries in nanocrystalline alloys can enhance the hydriding/dehydriding rates and capacity3,4.
It is evident that M (Cu, Co) substitution generates the visible refinement of the grains of the as-cast alloys.
The enhanced hydriding kinetics is principally ascribed to the refined grains by melt spinning.
The huge number of interfaces and grain boundaries available in the nanocrystalline materials provide easy pathways for hydrogen diffusion and accelerate the hydrogen absorbing/desorbing process10.

Mileage pile number design is K274+675—K291+000, 16.325km.
K276+500~K277+000 K276+000~K276+500 Fine grained asphalt concrete(3cm) Fine grained asphalt concrete(3cm) Medium grained asphalt concrete(4cm) Fine grained asphalt concrete(4cm) Upper base of the graded crushed stone(12cm) Upper base of the graded crushed stone (15cm) Cement-stabilized sand gravel base(20cm) Cement-stabilized sand gravel base (20cm) Old road Old road Fig.2 The conventional semi-rigid base asphalt pavement structure type Establish a hierarchical analysis model Classifying cold regeneration technology factors involved, streamline and hierarchical, constructing a hierarchical structure of factors.
Every index of second layers below also includes numbers of indexes of third layers.

A large number of experiments showed that using the traditional separation process for oolitic hematite is unable to obtain a good sorting index [3-5].
Iron mineral grain size is generally between 0.01 ~ 0.2mm, rare earth mineral grain size is between 0.01 ~ 0.06 mm and most niobium mineral grain size is smaller than 0.04 mm
Yuexin Han [15] used the depth-reducing technology dealing with Bayan Obo oxide ore, according to the reducing materials characteristics of complex mineral composition, coarser metallic iron grain size and higher residual carbon content, first using combined magnetic-gravity separation process to pre decarbonize, then by stage grinding - coarse and fine ores sorting flowsheet to separate iron, obtained the iron concentrate of the iron grade 92.02%, metallization rate 94.18% and iron recovery rate 93.27% which can be used as raw material for steelmaking, and the tailings of rare earth grade 15.10% and the recovery rate 97.18% which can be used as the raw material to separate rare earth.
Meanwhile, they thought that magnetic concentrate rich large number of small iron particles is the high-quality nucleating agent in nickel laterite depth reduction.

Under the observed of microscope, the cracking is along the material grain boundary or through the grain.
Since the undeformed chip average thickness of single grain decreases with wheel speed increasing, the plastic deformation depth decreases with the number of effective abrasive increasing.
Fig.5 Grinding experiment process Table 1 Surface residual stress Specimen number Depth of cut ap (μm) Workpiece speed vw (m/s) Wheel speed vs (m/s) 1 15 0.01 37 2 50 0.01 37 3 50 0.03 37 4 80 0.03 37 5 100 0.03 37 Experiment results.
Because grinding wheel grain can wear surface material easily with its sharp shade when cutting depth is small, the temperature and grinding force cannot produce a higher residual stress.

Polycarbosilane (PCS) with an average number molecular weight of 1100-2000 and a soften point of 200-220°C was obtained from Suzhou CeraFil Ceramic Fiber Co., Ltd of China.
Polyborazine (PBN) with an average number molecular weight of 800-1500 and a soften point of 60-80°C was purchased from Institute of Process Engineering, Chinese Academy of Sciences (IPE-CAS) and used as the precursor of BN.
Moreover, previous research showed that Si-C units were homogeneously dispersed around the B-C-N matrix grains.
(a)flexural strength,(b) fracture toughness Based on the previous research, the slight increase of flexural strength and fracture toughness with the PBN weight ratios from 0% to 30% might be attributed to the inhibition effects of B-N-C phase converted from PBN component on the growth of SiC grains.
That is, the fine SiC grains were scattered evenly around the continuous B-N-C phase in the ceramic matrix, and the inhibition effects of B-N-C phase on SiC grains growth could relieve the stress near the crack tip which the decrease damage of SiC fiber effectively.

Introduction Nanometer material is defined as the superfine materials with grain size within 1-100 nm, including nanometer ultra-fine particle, nano-bulk material and nanometer synthetic material[2].
These materials are characterized by high strength and low price but can not enable deep injection due to limited grain diameter.
Grain size of phase particles dispersed in the microemulsion is within 10-100 nm, therefore the microemulsion is also referred to as nanometer microemulsion.
A large number of researches with respect to microemulsion flooding formula and technology have been performed nationally and internationally.
Mechanism of flooding by using nanometer microemulsion fluid is complicated and is affected by a large number of factors such as wettibility of rock surface and change of oil-water interfacial viscosity or rheology.