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The unrefined base alloy is comprised of large, dendritic grains with the average grain size of 180m, as shown in Fig 1(a).
The refined alloy still exhibits small equiaxed grains and maintains the grain size level at 40 m.
Based on the above analysis, the superior stability of the fine grains in the base alloy with Al addition stems from the grain growth restriction provided by the large number of 'inactive' Al2Y particles together with the unknown Mg-Al-Y particles along the grain boundaries.
In addition, these grain boundary particles also suppress grain boundary sliding, which compensates the reduction of creep resistance owing to the grain refinement.
Discussion The inoculation in both cast Mg alloys produces a large number of inactive Al2Y particles, but the particle distribution may be different.

Thirty Years of Superplastic Ultrafine-Grained Materials: Examining the Legacy of Oscar Kaibyshev Terence G.
Since this grain size was exceptionally small, and smaller than any grain sizes available in western scientific research at that time, the author communicated by mail with Oscar Kaibyshev and immediately received an invitation to visit Ufa.
Processing by SPD to produce exceptional grain refinement can lead to exceptionally high superplastic elongations even in materials where the numbers of slip systems are limited, as in Fig. 8 where there is an elongation of 3050% in an Mg alloy processed by ECAP [13].
Langdon, A unified approach to grain boundary sliding in creep and superplasticity, Acta Metall.
Langdon, Ultrafine-grained materials: a personal perspective, Int.

During annealing at temperatures from 800 to 1000 °C, a large number of equiaxed grains as fine as few hundreds of microns were found embedding in the matrix; the recrystallized grains stay quite stable and show minor dependence on annealing temperature and time.
After being heated to 1200 °C for extended time, abnormal grain growth took place and resulted in bimodal grained structure.
There are still a large number of dislocations tangled with second particles even after being heat treated at a high temperature for hours.
The nano-crystalline grains (54nm) in as-milled powder grow to ultra-fine (about 500 nm, Fig. 4b) equiaxed grains.
After annealing from 800 to 1000 °C, a large number of equiaxed grains with few hundreds of microns are found to recrystallize in the matrix and preferentially to located on interfaces.

According to iconic two-dimension grain-size analysis, and contacting to fundamental sedimentary characteristics of conglomerate, sedimentary environment analysis is carried out.
Grain-supported type is mainly matrix support structure and grain-supported structure.In the matrix support structure, the matrix content is high, gravel particles are generally smaller and the particles in the matrix is floating.In the grain-supported structure, between the particles varieties of contact manners existed, the common are wired contact, bump contact and stapling contact, but also a bit point contact.
Through the comprehensive study of the large number of samples, sediment grain size probability cumulative curves in the study area are mainly the following three types
The type of granularity probability curve is similar to turbidites granularity probability curve, mainly reflected the characteristics of the grain size of mudslides and debris flows
Accordingly identify the total of 9 categories lithofacies that are linear grain-supported matrix-free massive bedding solution pores conglomerate phase(Gclm), linear grain-supported fine gravel matrix massive bedding mid-conglomerate phase(Gmclfgm), point-type grain-supported coarse sand matrix massive bedding uniform mid-conglomerate phase(Gmctcsm), point-type grain-supported coarse sand matrix massive bedding mid-conglomerate phase(Gmctcsm), matrix (grit) supporting massive bedding mid-conglomerate phase(Gmmcsm), point-type grain-supported coarse sand-fine gravel matrix massive bedding mid-conglomerate phase(Gmctcs-fgm), single coarse conglomerate phase(Gc), all kinds of coarse sandstone phase and various types of mudstone

Alloy added into the aluminum melt after stir the melting and mixing, heat preservation 10min after pouring into the four cast, which was followed by the number 4 group No.1 ~ No.4 (n = 4, the steel mould, graphite mould ,copper mould and Water-cooled copper mould number were a, b, c, d) test like.
Among them, die casting of No.2 (a) and No.3 (a) sample grain size is larger, the water-cooled copper mold casting of No.2 (d) and No.3 (d) sample grain size.
From the experimental results, has an important effect to the formation and size of aluminum melt pouring temperature on Al-5Ti-B alloy microstructure refinement of pure aluminum ingot of equiaxed grain, especially as the mass fraction of Al-5Ti-B alloy is 0.2% and below, the pouring temperature of melt increases, ingot organization columnar grain number, grain size.
In the Al-5Ti-B alloy additions are the same, because the cooling speed melt faster, a lot of equiaxed primary crystal formation type wall can be preserved in the melt more equiaxed dendrite microstructure, the number of the more, the more fine grain.
Conclusion The TiAl3 and TiB2 contained in Al-5Ti-B alloy have good grain refinement ability for commercially pure aluminum, and the cooling rate and casting temperature have significant effects on the number and size of equiaxial crystal.

So the multi-pass equal channel angular pressing can achieve good effect of grain refinement and improves the distribution uniformity of grain-size.
The extrusion material is industrial pure aluminum, the diameter of specimen is 30mm, the length of specimen is 260mm, the number of meshing elements is 41490, and the extrusion temperature is 20℃.
This shows that: the extrusions can achieve the effect of grain refinement owing to a strong shear stress in the direction of inside corners of the mold, while uniform distribution of the grains only can be obtained after multi-pass ECAP
The results can confirm that the multi-pass ECAP can effectively achieve the effect of grain refinement, and increases the distribution uniformity of grain.
Acknowledgements This work was financially supported by the Guangxi Natural Science Foundation (Gui Ke Qing: 0832006) and the open foundation of the key laboratory of new processing technology for nonferrous metals and materials, Ministry of Education, Guangxi University (Contract Number: GXKFJ-17).

Further deformation in strain leads to a higher number of banded structures and the formation of new, fine sub(grains) in the regions with high density of banded structures (Fig.2a).
The grain growth in the range of 1s- 60 min is rather gradual, but above 60 min of annealing rapid grain growth was observed.
The lower hardness of the samples annealed in the range of 30- 120 min indicates the presence of recrystallized grains with minimum number of residual dislocations.
The as-deformed microstructure of mono Cu consists of ultrafine grains with a high fraction of low angle grain boundaries.
The grain size is stable up to an annealing time of 15 min.

The grain diameter reduced from 45µm to 2.8 µm after 6 passes of ECAE.
The refinement in grain size causes dislocation pile- up at the grain boundary, which impedes dislocation movement and increases the yield stress of the material.
His study also included the optimal choice of the processing route and number of passes.
Their results demonstrated that the grain size of the alloy gradually reduced with the increase of the pass number and the mechanical properties were significantly improved after the ECAE.
Fig.8 shows Scatter plot of the Vickers Microhardness across the flow direction for different number of passes.

Although the number of triple junctions depends on the number of boundaries, all peculiarities in the behavior of polycrystals during grain growth have been solely attributed to the motion of grain boundaries so far.
The grain boundary GB12 was vicinal to a twin boundary 60° <111>, and the other two grain boundaries were random high-angle grain boundaries.
Grain 2 Grain 3 Grain 1 Fig. 7.
The normal grain growth is driven by curvature, particularly of grain boundaries at conventional grain size, but predominantly by triple line curvature at nanometer grain size dimension.
The triple line excess energy is the difference between the total energy of a polycrystalline volume and the total energy of a single crystal with the same number of atoms plus the excess energy due to the grain boundaries present.

The grain size of sample processed by multi-pass ECAE was reduced with the extrusion number.
The EP shifts to more positive values with increasing the ECAE pass number until four-pass.
It is noted that the grain size of multi-pass ECAE samples decreases with the ECAE pass number.
Effect of the number of ECAP pass time on the electrochemical properties of 1050 Al alloys.
Corrosion resistance of ultra fine-grained Ti.