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However, severe plastic strains >> 1 can be reached either by increasing the number of forming sections in the tool system or by increasing the number of passes, for instance by reversing the feed direction.
Microstructural evolution Fig. 6 Grain size distribution of Cu samples before and after processing with ECAS.
The grain size distribution in Fig. 6 and the high angle grain boundary (HAGB) map in Fig. 7 show that ECAS generates a significant grain refinement while keeping a globular morphology.
Fig. 7 High angle grain boundary map (> 15 ° misorientation) derived from EBSD measurements of Cu samples (transverse section) in the as received state (a) and after 28 ECAS passes (b).
In order to extend the grain refinement to the UFG region the channel angle will be decreased in future studies.

The material removal processes include chipping out of lateral cracks caused by impact of the erodent particles, grain boundary cracking and grain pull out, as well as plastic deformation caused by the repeated sliding and impact of the particles.
The eroded surface is considerably rougher and areas of material removed by grain ejection and chipping out are visible.
Note that the erosive wear mechanisms (material removal processes) include: A, chipping out of lateral cracks; B, grain boundary cracking and grain pull out; C, plastic deformation.
In this study, the mechanical wear maybe includes the flowing mechanism (Fig.3): chipping out of lateral cracks, grain boundary cracking and grain pull out, plastic deformation.
The material removal processes include chipping out of lateral cracks, grain boundary cracking and grain pull out, as well as plastic deformation caused by the repeated sliding and impact of the particles.

By analyzing the microstructure of the drawn-cup walls at different temperatures, it is found that grains were stretched along the direction of tension at temperatures lower than 423K.
And there appeared a large number of fine recrystallized grains when forming temperature is 423K showing that dynamic recrystallization occurred during forming process.
a c b d Fig.5 The microstructure of drawn cup walls at different temperatures 403K b) 423K c) 443K d) 473K It can be seen from Fig.5a that, due to the presence of the intragranular slip, the size of the grain has been stretched along the direction of deep drawing during the deformation at 403K, but when the temperature is elevated, it can be observed clearly that the dynamic recrystallization occurred resulting in a large number of the small recrystallized grains, meanwhile the microstructure were refined, but there were still a number of large size of grains in most part of the microstructure at 423K.

Fig. 2 The position of the (002) peak, film strain and grain size of the samples Compared with undoped films, all the (002) peak center biased to small angle and film strain in the crystal increased, the average grain size grew from 17.1nm to 21.7nm.
The undoped film has smooth surface and compact structure with small crystal grain.
The voids between the grain boundaries also become bigger.
%Na-doped film exhibit highest crystalline quality with a more intense and sharp (002) diffractive peak and the lowest grain strain.
With the increase of Na doping content, the grain grow larger, the film surface get more flatter and smoother and the number of voids decreased.

Unrecrystallised grains were characterised by large grains elongated in the extrusion direction while the recrystallised grains were smaller and equiaxed in nature.
Grain sizes for the alloys.
In the as-cast state, ZE21 has the largest grains (Table 2) and thus the least number of recrystallisation nucleation sites.
With such a large initial grain size, after extrusion the microstructure of ZE21 retains a large fraction of unrecrystallised grains (Fig. 4b).
Thus, the grain size of the compressed-annealed grain size increases (Table 2).

The linings are comprised of rod-shaped Al2O3 matrix eutectic grains.
The diameters of tetragonal lattice ZrO2 fiber in rod-shaped grains are on nano-micron scale.
The average size and the size distribution of grains and nano-submicron phases were determined by using the linear intercept method on a SEM photograph.
As a result, a large numbers of fine low-energy heterophase interfaces and high compressive residual stresses in the rod-shaped eutectic grains resulted in the reinforcement of the eutectic grains.
Meanwhile, high-energy, large-angle boundaries between rod-shaped grains introduce the strong toughening mechanisms involving crack-bridging and pull-out of rod-shaped grains in the wake of crack tip.

Before 60 minutes, the mean particle size is slashed, however, the range of varying mean particle size is less after 60 minutes under the ball milling rotate speed for 200r/min and the charge amount for 200g/L, so the ball milling time for 60 minutes is decided.The mean grain size of quartz powders are decreased vary with an increasing the ball milling rotate speed, and the rotate speed is lower, the distribution is wider, however, the rotate speed is higher, the distribution is narrower.The mean grain size of quartz powders are 11.25μm via a roller ball milling, the mean grain size of quartz powders are 7.37μm via a planetary ball milling, and the particle size distribution of quartz powders milled via a roller ball milling is wider than that of quartz powders milled via a planetary ball milling, which shows the of quartz powders milled via a roller ball milling is not more uniform than that of quartz powders milled via a planetary ball milling, the asymmetry powder is advantage for forming
Fig.1 Relation of ball milling time and the mean particle size of quartz sand powders The relation of ball milling rotate speed and particle size of quartz powders is shown in Fig.3, which shows the mean grain size of quartz powders are decreased vary with an increasing the ball milling rotate speed.
Because the rotate speed is increased, the milling number and the acting force between ball milling media and quartz are both increased, it makes the effect of ball milling strengthen, the particle size of quartz powders are decreased.
Fig.3 Effect of the ball milling rotate speed on the grain diameter of quartz sand powders Fig.4 Effect of the ball milling rotate speed on the microstructure of quartz sand powders Fig.5 Effect of ball milling methods on the particle size of quartz sand powder materials The relation of ball milling methods and particle size of quartz powders is shown in Fig.5, which shows the mean grain size of quartz powders are 11.25μm via a roller ball milling, the mean grain size of quartz powders are 7.37μm via a planetary ball milling, and the particle size distribution of quartz powders milled via a roller ball milling is wider than that of quartz powders milled via a planetary ball milling, which shows the of quartz powders milled via a roller ball milling is not more uniform than that of quartz powders milled via a planetary ball milling, the asymmetry powder is advantage for forming the high performance building materials body.
Before 60 minutes, the mean particle size is slashed, however, the range of varying mean particle size is less after 60 minutes under the ball milling rotate speed for 200r/min and the charge amount for 200g/L, so the ball milling time for 60 minutes is decided.The mean grain size of quartz powders are decreased vary with an increasing the ball milling rotate speed, and the rotate speed is lower, the distribution is wider, however, the rotate speed is higher, the distribution is narrower.The mean grain size of quartz powders are 11.25μm via a roller ball milling, the mean grain size of quartz powders are 7.37μm via a planetary ball milling, and the particle size distribution of quartz powders milled via a roller ball milling is wider than that of quartz powders milled via a planetary ball milling, which shows the of quartz powders milled via a roller ball milling is not more uniform than that of quartz powders milled via a planetary ball milling, the asymmetry powder is advantage for forming

Annealing twins were observed in equi-axed grains.
The mean grain size was about 23μm.
Number fraction and average of misorientation angle of Cu-15at%Al as a function of equivalent strain, (a) 0 and 0.25, (b) 0.53 and 1.13, and (c) 1.44 and 2.60 The hardness increased with increasing reduction, while the slope, i.e., strain hardening rate, gradually decreased as seen in Fig. 6.
Twinning in grains which were predominated is saturated.
These shear bands intersect, so ultrafine grains are formed.

This advantage causes the minimization of tooling costs thanks to the reduction of the number of preforms used to obtain the final component.
Grain growth increases the grain size created during recrystallization at temperatures higher than δ solvus temperature (1010ºC) [3].
Influence of initial grain size.
Grain size results are plotted in figures below.
Influence of initial grain size: different initial grain size has less importance if recrystallization is guarantee.

We can see that the surface is smooth, the grains are fine and tight integration on the films deposited on substrate at 50 ℃, while grain is bigger, surface is coarser and looser at 200 ℃.
When temperature is lower, free energy of critical nucleation declines, number of nuclei formed increases, which helps to form continuous organization of films with small grains; when temperature is higher, larger critical size and higher free energy of nuclei formed are needed, which helps to form bulky island organization of films.
It can be seen from Fig. 4 that grains are irregular shape before annealing, and polygonal shape after annealing.
Heat treatment makes grains recrystallize, surface smooth, particles uniform, structure dense and defects reduced.
Grains are irregular shape before annealing, and polygonal shape after annealing