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Fig.1b shows that when the welding current is increased to 9.5kA, in the action of both high temperature and electrode pressure, plastic deformations and a strong recrystallization happens to the joints, which causes the following consequences: Grains become smaller, the growth of columnar grains is restricted.
Coarse columnar grain regions are significantly reduced and an equiaxed zone as large as about 100μm on the periphery of nugget is formed, namely plastic ring (Fig.1c).
As can be seen, when the welding current is 7.4kA, it presents a mixed fashion of joint river pattern and partial dimple pattern, and dimple number is small, belonging to mixed fracture.
When the welding current is increased to 9.5kA, a large number of dimples arise from the fracture.
At the same time, a large number of splashes arise because the liquid metal with high flow velocity in fusion nucleus breaks through the plastic ring.

The result of field test showed that: the average seed space is 150mm; the working speed is 4.3km/h; the pass rate of grain distance is 96.7%; the vacancy rate is 0.8%, the pass rate of seed number is 99.2%.
The multifunctional water-saving mulching planter designed in this paper combines some characteristics developed by fertilizing, spraying, drip tape laying, laying film, drilling, planting and a number of other operations.
Table 2 Performance experiment results Projects Test results The machine speed [km/h] 4.3 The wheel slip ratio [%] 4.6 Vacancy rate [%] 0.8 Seed machinery breakage rate [%] 0.2 The qualified rate of seeding depth under film [%] 91.7 The thickness of the overlying soil seed yield [%] 95 Seed number qualified rate [%] 99.2 The qualified rate of hole spacing [%] 96.7 Hole dislocation rate [%] 0 The covering rate of film hole [%] 100 The fertilizer quantity consistency coefficient of variation [%] 7.9 The amount of spraying [kg/ hm2] 550 Summary and Conclusions Field performance test shows that its performance is advanced: planting corn, the seed spacing is 150mm; the speed is 4.3 km/h; the pass rate of grain distance is 96.7%; the vacancy rate is 0.8%, the pass rate of seed number is 99.2%.

Grain size analysis was carried out using the linear intercept method.
Additionally, there are fine equiaxed grains contain columnar grains between them.
However, the DC casts have fine equiaxed grain structure throughout their entire cross sections of average grain size of about 47mm.
Therefore, a large number of GP zones and h¢ phases which are smaller than the critical size are re-dissolved during the early stages of the retrogression step.
Finally, the number of nucleus that can promote re-precipitation of GP zones and phase in the re-aging step is decreased, and it becomes difficult for GP zones and h¢ phase to precipitate out of the matrix in the re-aging step.

The microstructural input parameters are the composition, the dendrite arm spacing (DAS) and the grain size.
The size distribution (in terms of relative numbers of particles) as well as the mean size of the constituent particles for a 6060 alloy in as cast condition is given in Figure 4b).
Reducing the amount of grain refiner rod will therefore give a significant cost saving in the casthouses.
In order to test the effect of different grain refinement on foil quality three 5.5m long sheet ingots (Figure 5) with different grain refining practises were cast at the reference centre and shipped to the rolling plant Norf.
Samples were collected along the whole process chain in order to follow the effect of the different grain refining practises on resulting microstructures (particle structures, grain structures).

As the heat treated temperature was increased from 550 °C to 620 °C, the amount of η (MgZn2) phase decreases and a great number of particles Al2Cu precipitates in the powders interior.
In Fig. 1(b), the microstructure of atomized Al-5.8 % Zn-1.63 % Mg-2.22 % Cu-0.12 % Zr powders exhibited a fine, homogeneous microstructure with spherical grain morphology.
This can be attributed to the presence of more prior particles boundary networks and the presence of particles which are inhibiting the migration of liquid film[9].When the powders heat treated at higher temperature, such as 620 °C and 638 °C, a liquid wets the grain boundaries.
At the heating temperature 638 °C, large number of bright particulates identified as Al2Cu were precipitated at grain boundaries.
With the increasing forming temperature, the amount of η (MgZn2) phase decrease and more particles Al2Cu were precipitated at grain boundaries

The original HA surface was composed of smooth faceted grains with a maximum dimension, d, of 1.17 ± 0.76 µm, as determined via CMAFM height images (data not shown).
The initial HA surface was found to have an intergrain (across grain boundary) peak-to-valley height, h, of 119.84 ± 74.81 nm and an intragrain peak-to-valley feature height, h, of < 1 nm.
The underlying HA grain boundaries were still visible after SBF incubation and the SBF-incubated HA surface showed grains with d = 1.05 ± 0.47 µm, statistically similar to the initial HA grain size (p<0.05).
As shown in Fig. 2b, each of these morphologies was localized within individual grains or facets.
Transitions between the different surface morphologies appear to be located at the underlying grain boundaries or possibly underlying facets.

When quenching from the liquid phase, the structure has a number of features [1-3]: 1.
Formed during primary crystallization dendrites are small in size, due to the formation of a large number of crystallization centers. 2.
This is accompanied by grain refinement, an increase in the density of defects and an increase in stresses in the crystal lattice.
A shock wave generated in a laser plasma creates conditions for intense plastic deformation, resulting in the formation of an ultrafine-grained structure with nanocrystalline grains less than 100 nm in size.
The predominant deformation mechanism during laser hardening is the twinning process, which is determined by pressure; crystallographic orientation (twinning is carried out when the resulting shear stress reaches a threshold value in the twinning plane and along the twinning direction); the energy of packaging defects (a decrease in the energy of packaging defects leads to an increase in the number of twins in the structure); pulse duration (with an increase in pulse duration, the number of twins increases); grain size.

The substitution of Pr for La brings on a notable grain refinement of the as-cast alloys instead of altering the phase structure of the alloys.
It is very evident that the substitution of Pr for La brings on the visible refinement of the grains of the as-cast alloys.
Fig. 4 elucidates the evolution of the capacity retaining rates (Sn) of the as-cast and spun Pr0.1 and Pr0.3 alloys with the cycle number.
The capacity retaining rates (Sn) of the as-cats and spun (15 m/s) alloys as a function of the cycle number is presented in Fig. 6.
The substitution of Pr for La incurs the obvious refinement of the grains of the alloys instead of changing the phase compositions of the alloys.

In oligocyclic loads domains, a number of specific degradation mechanisms appears.
But at higher temperatures, the area where the crack initiation starts formation is the grains boundaries.
In [2] it is developed the opinion that especially the attack through oxidation, along the grains boundaries reduces lifetime.
The characteristics of applied cycles and number of these cycles untill the break are shown in (Table 4).
Sometimes, the ratio of load cycles calculated number untill failure and experimental number is greater than 10.

Alipour, et al. [10] found that grain size reduction was performed up to 0.1 wt. % Ti addition and higher addition resulted to constant grain size.
It can be clearly seen that the studied alloy structure underwent inconsiderable grain refinement, but grain rounding.
It even possessed higher grain size when compared with higher Ti content Al alloy, Al-5.1Zn-1.8Mg-0.4Ti [11], which grain size was 67.3 µm.
Meanwhile, aggregation of TiAl and TiAl3 were predicted at grain boundaries which aimed to restrict the grain growth.
Meantime, the number of vacancies at 220 and 420 °C were 0.13 x 1022 and 21.23 x 1022, respectively [2].