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The number of deposition–irradiation cycles was 20.
The fragment volume features a substructure (Fig. 1b) whose size increases with increasing the number of pulses in a cycle N and the beam energy density ES.
The grain structure of the Al substrate is also modified during its multicycle surface alloying with Ti (15 J/cm2, 50 µs, 10 pulses).
Near the interface with the alloyed layer, the size of Al grains is 1÷2 µm (Fig. 6a).
In going deeper from the treatment surface, the size of Al grains increases to 4÷5 µm (Fig. 6b), and the grains are broken into subgrains with low-angle boundaries.

Table 1 Mechanics performance statistics before process optimization in P560L Category Standard request Min Max average Rel/MPa ≥450 455 600 487 Rm/MPa 560~680 555 675 586 A/% ≥23 17 31 24.3 Fig.1 Tensile strength and elongation distribution before process optimization in P560L Microstructure examination Different extension rate of P560L microstructure analysis the results in Table 2, the typical microstructure is shown in figure 2.From table 2 and Figure 2 shows: high elongation sample tissue for ferrite and pearlite, grain size grade for Grade 10; low elongation sample section organization exists certain differences, a ferrite + pearlite, ferrite grain with needle-like trend, mixed crystal is serious; the other side for ferrite and bainite structure, thickness of 2.5 ~4.8mm range, the steel plate 1/4 above.
Table 2 The analysis results of microstructure before process optimization in different elongation of P560L sample numbers elongation /% microstructure grain degrees/level bainite thickness/mm 1# 28.5 ferrite + pearlite 10.0 / 2# 23.5 ferrite + pearlite 10.0 / 3# 21.5 one side ferrite + pearlite; the other side ferrit+ bainite / about 2.5 4# 17.0 one side ferrite + pearlite; the other side ferrit+ bainite / about 3.0 1#（A=28.5%） 2#（A=23.5%） 3#（A=21.5%） 4#（A=17%） Fig.2 The typical microstructure in different elongation of P560L Fracture appearance observation Using JSM-5600LV scanning electron microscope, the tensile sample fracture SEM energy spectrum analysis, the results show that, in the near the fracture without obvious inclusions, the tensile fracture morphology as shown in figure 3.The tensile fracture surfaces extending from visible, higher rate of sample a and sample two, mainly for the apparent dimple, only a small amount of cleavage
fracture; elongation lower sample three and sample four fracture partial dimple dimple, and is elongated in shape, dimple near the presence of a large number of cleavage fracture. 1# 2# 3# 4# Fig.3 The fracture in different elongation of P560L Analysis From the above analysis result, P560L three mechanical properties, elongation and standard maximum difference, is affects the P560L performance qualification rate main index.The reason of low elongation is related to metallurgical structure exists a certain thickness of bainite in.This is because as the strip thickness increases, will appear with the thin gauge strip a number of different characteristics, such as the deformation is not deep, large temperature gradient in thickness direction, head low temperature [1].
And in the rolling thick gauge strip, in the middle of roller and rolling temperature drop is low, accelerate the recrystallized austenite grain growth speed, causing the phase transformation of ferrite grain size increases, and in the finishing process, the total deformation rate is low, this will lead to performance degradation.The strip thickness and the cooling rate has a good linear relationship, with the continuous cold strip thickness increases, the cooling rate will gradually decrease, cooling, if continue to use the production of thin gauge cooling process, due to the thickness direction of the temperature gradient is larger, easy to make the steel roll surface due to cooling too quickly and the emergence of bainite, the abnormal tissue appear to lead to extension rate is significantly reduced, but this phenomenon is not reflected in the coiling temperature control to meet.Therefore the use of thin gauge rolling production process of thick 560MPa grade automobile beams plate is
The intermediate billet thickness is greater than or equal to 38mm control, proper increase of cumulative strain in rolling process, increase the ferrite nucleation core, thus refine ferrite grain.

Fig.1 Tensile specimen size figure Removed the burr of the sample surface, and numbered 10 groups of sample, each group contains three parallel samples.
The figure 2b and 2c show that with the increase of the content of rare earth basic remains the same, alpha beta phase number, have great changes, and the distribution form by thick mesh gradient for the tiny granule.
By figure 2d, rare earth content is increased to a certain amount, the increase of the rare earths are not further promote the grain refinement, on the contrary make grain overgrowth of.
The grain overgrowth of resulting in a decline in the tensile strength of the alloy at the same time reduce the hardness of the alloy.
Taylor.Grain Refinement of Magnesium Alloys: A Review of Recent Research, Theoretical Developments, and Their Application[J],2013,44(7)

The grain-like patterns in Fig. 2 are pits formed at the SiC/Si interface.
As shown in Fig.2, the number of pit dramatically decreases according to the increase in process pressure.
Pit density means the number of the pit for each unit area.
The diffusion coefficient of the silicon atoms at the grain boundary could not be obtained because the vapor pressure of silicon at the grain boundary is very high [4].
The concentration of carbon atoms in the grain boundary of SiC film is shown in Fig. 7.

TEM micrograph of Si containing Al-Zn-Mg-Cu cast alloy showing the PFZ along the grain boundary.
As will be shown later, the crack propagated through the grain boundaries.
Further study is needed for more comprehensive understanding. 1000 10000 100000 1000000 1E7 100 120 140 160 180 200 Base Si Cr Alternating stress, MPa Number of cycles to failure PFZ 10 100 1000 10000 0.25 0.30 0.35 0.40 0.45 0.50 Base Si Cr Total strain amplitude, Number of cycles to failure Table 2.
Fatigue crack propagation path of Al-Zn-Mg-Cu cast alloy along the grain boundary.
It shows clearly that fatigue crack propagated along the grain boundary.

SSNC uses a non-equilibrium treatment method to increase the free energy of the surface of the material, leading to the server grain refinement of the surface coarse grains into the gradient surface microstructure along the depth direction with nano-grains, ultra-fine grains (UFG) and deformed coarse grains.
Further accumulation and entanglement of intercrystalline dislocation network caused the surface grain to break into a large number of subgrains and nanograins.
In addition, The TEM micrograph of α-Cu grain after SSNC treatment was also observed by Song et al. [24]. α-Cu grain is refined into equiaxed nanometer grain with an average size of 400 nm.
This phenomenon was caused by the high-density grain boundary number that divides the continuity of dislocations in the grain and hinders the slip development of dislocations [26].
When the highly active metals with the nano-structured layer are immersed in the corrosive medium, the large number of grain boundaries of the nano-structured layer provides greater corrosive activity, which exacerbates the dissolution rate of the anode, that is, the higher corrosion rate.

By comparing with the microstructure of the ceramic far away from the surface-alloyed layer, the one of the TiC-TiB2 ceramic contact with the surface-alloyed layer was obviously refined, so that the fine-grained microstructure of the TiC-TiB2 ceramic is observed in Fig. 3(b).
FESEM images of high magnification show fine-grained microstructures (characterized by the average thickness of TiB2 platelets close to 1 μm) come into existence generally in the TiC-TiB2 ceramic that is sided by the surface-alloyed layer, as shown in Fig. 3(b), the average thickness of TiB2 platelets measured 1.56 µm.
Hence, the achievement of fine-grained micro- structures which contribute to improvement of bonding strength is considered closely to be dependent on solidification behavior under high cooling rate.
The TiC-TiB2 ceramic was composed of a number of fine TiB2 platelets, irregular TiC grains and a few of Cr-based binder and Al2O3 inclusions.
TiC-TiB2 ceramic, surface-alloyed zone of Ti alloy, HAZ of Ti alloy and raw substrate of Ti-6Al-4V, and within surface-alloyed zone of Ti alloy a number of ultrafine TiB platelets, TiB2 platelets and fine Ti-enriched carbides were embedded in the matrix of α’-Ti martensite and the achievement of a number of ultrafine TiB platelets is considered a result of peritectic reaction of TiB2 and liquid Ti alloy following the nucleation of TiB2 as the primary phase in Ti-enriched melt of liquid TiC-TiB2.

N - general number of measurements of radiuses r.
Their microstructure is the effect of simultaneous solution and abrasion (grain-to-grain collisions) in high energetic subaqueous environments, such as the littoral zone [9, 11, 21].
Particles NU, T106_3a and Kowary_0,65 possess a growing number of sharp edges and corners.
It takes into account the number of sharp corners, their acuteness and distance from the same point (Fig. 2).
Mahaney, Atlas of sand grain surface textures and applications.

As can be seen, the grain growth of the four samples is uniform, the average grain sizes are between 12um-15um, they have a better sintering density.
With the increase of the impurity content of NiO and CoO, more uniform grain size has.
But when further increase of impurities, some areas appear more obvious larger grains and there are more blowholes in the grains and grain boundaries .
It can be seen doping appropriate amount of NiO, CoO optimization the grain , and move the blowhole to the grain boundary edge, the material has a uniform microstructure [11,12,13].
The appropriate amount of Co2+, Ni2+ doping will replace the Fe3+, Mn3+ on B bit , thereby increasing Fe3+ in A bit, so it increases the Fe3+-O-Fe3+ number .

NiSi grains adopt FeSi-type cubic unstable structure until final silicide phase appears.
It causes more probable nucleation in some grains then in another ones.
Not all grains of NiSi transform into NiSi2 simultaneously.
Some grains remain in form of NiSi for a long time.
By computer enumeration method as applied for a number of Si diffusion constants and the rate of oversaturation the best matching of calculated and experimental data was achieved.