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A number of Mg–Al based alloys such as AZ91D, AM60 and AM50 have been extensively used for manufacturing automotive components such as the, steering wheel[3,5],instrument panel[5], seat frame[5,8,9].
The number in brackets is wall thickness.
Fig.2a shows the typical microstructure of die-cast AZ91D ,which is mainly composed of α-Mg phase and the continuous network phase distributed along grain boundaries, the grain size is 67;with 1.0 wt. % RE added, some new irregular block-like phase emerged throughout grain boundaries beside α-Mg matrix and discontinuous network phase , while the grain size is 55;increasing RE to 2.0 wt. %, grains are coarsened ( 83) decorated with lots of new phases emerge in the form of irregular larger block-like within grain or distributed along grain boundaries, the number of phases seem to be decreased, due to it is very cleaner within grains, but nearly network phase nearly disappears. .
Fig.4 (a) shows SEM image of Mg,Al,Mn and Zn elements for die-cast AZ91D alloy, it is obvious that Mg element existed within the grain,Zn element uniformly distributes within the grain or grain boundaries, while grain boundary area contains almost all the Al element and Mn element usually appears in the form of particles.
%RE alloy, the average grain is about 55 μm and 83μm, respectively.

Figure 3 shows the primary phase in CA1 are coarse columnar crystals, dendrites developed, large grain size, only a small amount of equiaxed grains distributed in the central part; the most primary dendrites in CA2, CA3, CA4 become small and smaller equiaxed and uniform.
The primary phase in CA4 most obvious grain refinement, are relatively uniform fine.
The CA4 have small dimples larger size, which is the grain boundary interface thicker discontinuous distribution of second phase particles.
Large number of small dimples evenly distributed around a large dimple.
Nano-SiC powders also can be used as heterogeneous nucleation, played the role of crystal nuclei, and increased the number of nuclei, refine nuclear grains of the aluminum bronze role.

Evolution of crater density with pulse number.
These micro-irregularities can be grain boundaries, small precipitates or phase boundaries.
It has the finest structure and contains more grain or phase boundaries.
Evolution of crater density with the number of pulses.
Craters nucleate in the sub-surface at grain boundaries as well as precipitates and burst through the melted surface.

A large number of channels connect the larger open spaces and the sample surface.
Number of pores N In a powder compact there is only one (continuous) pore.
Pore number reaches a maximum when G goes to zero and decreases in the late sintering stage.
Here, VV (solid) is the volume fraction of the solid phase (VV (solid) =1 - VV), and PL(grains) is the number of grains per unit length of the scanning line.
A large number of mechanisms have been identified to be relevant for porosity coarsening.

Fine-grained parallel execution is an elegant way to speed up sequential simulations.
The simulator works strictly as master/worker(s) paradigm for fine-grained parallel and distributed stochastic simulations.
Communication costs are crucial to the performance of a fine-grained parallel and distributed simulation.
The influence of the number of cores used in parallel simulation is investigated.
Miller, "Random number generators: good ones are hard to find," Commun.

Martorano et al. [4] observed columnar grains oriented approximately parallel to the cylindrical ingot axis at lower mold velocity and a large refining effect at lower velocities.
However, it is still lack of a method for precise control of dislocation density, growth orientations, and grain boundary (GB) type of UMG-Si ingot.
The dislocation density in the central part was less than that at the bottom and top because of slight supercooling, larger grain sizes, and complete growth of columnar crystals.
Recent studies showed that the presence of a large number of carbon sources in the silicon melt could promote formation of the ∑3 boundary.
Fig. 2 Distribution profiles of dislocation Fig. 3 Distribution of grain boundary type density along the cross section of the ingot in the middle part of the UMG-Si from bottom to top Conclusions The dislocation density in the ingots increased with the withdrawal rate increase.

Grains induced by dynamic recrystallization are immediately included into the process of forming.
The nuclei that develop mainly at the grain boundaries are still aligned according to the basal character of the old grain [5].
Considering the area of cold forming, other effects such as the insufficient number of slip systems are predominant, which affects the general formability in a negative way.
Due to the previous deformation of structure the nucleus orientation is unlikely to cause a basal texture in the newly formed grains.
After annealing the microstructure in both layers is completely recrystallized with a slight grain growth in the center.

These grains are more rounded in the case of AXJ530-ESTC specimens than for the AXJ530-SFTC.
(b) AXJ530 SFTC2 1&2 98.39 1.42 - - - α-Mg 3 75.72 12.17 9.72 - 2.97 Sr-rich particle 4 75.89 15.21 8.71 0.07 0.09 α-Mg + (Mg,Al)2Ca 5 1.93 52.47 0.09 43.16 - Mn-Al 2 See Figure 2c for spot numbers.
(c) AXJ530 ESTC3 1&2 98.39 1.48 0.06 - - α-Mg 3 76.12 14.60 9.14 - 0.06 α-Mg + (Mg,Al)2Ca 4 78.90 10.59 4.97 - 5.13 Sr-rich particle 5 30.79 42.80 25.77 0.32 0.11 α-Mg + (Mg,Al)2Ca 6 2.45 55.65 0.15 41.73 - Mn-Al 3 See Figure 2e for spot numbers.
However, after 60 minutes of immersion, severe corrosion occurred at grain boundaries as well as within the grains.
On the other hand, the two thixocast specimens were composed of large grains of pre-existing α-Mg phase and a fine microstructure, similar to that of the die-cast specimen, composed of finer α-Mg grains and eutectic constituents.

Experimental Procedures Cylindrical rods of Zirconium 9 mm in diameter were subjected to ECAP by routes C and BC at 350 oC with the number of successive passes up to 4.
An origin of the ultrafine-grained fraction can be of two kinds: (a) breakage of initial grains into fragments with increased defect content and lattice distortion; (b) formation of finest nuclei of new grains by dynamic recrystallization.
When comparing textures of rods, subjected to different numbers of ECAP passes, one can see, that deformation processes develop non-monotonically.
According to obtained results, in the case of ECAP by route C the texture nonuniformity through rod's cross-section becomes more significant as the number of passes increases.
Emergence of the minor ultrafine-grained fraction results in scattering of the ECAP texture.

The grains were observed by means of light optical microscopy (LOM) and polarized light after Barker’s electro-etching and their mean grain size determined.
Grain fragmentation by lattice rotation and grain boundary serration were observed at high Zener-Hollomon parameter (Z) meaning high strain rate and low temperature combination.
The grain size is inversely proportional to the Z parameter.
The continuous rotation of the lattice followed by formation of high angle grain boundary (HAGB) is responsible of the grain refinement at temperatures larger or equal than 400°C.
The authors thank to AMAG GmbH for the provision of the material and to the Austrian Agency of Research founds FWF for supporting project number [P22238-N22].