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Superplasticity of Ultrafine-Grained Aluminum Alloy Processed by ECAP and Warm Rolling R.K.
This UFG material was successfully rolled at temperatures of 330-370o C retaining small grain size and equiaxed grain structure.
The average grain size was measured according to the dark-field image, averaging by the number of values more than 100 measurements.
At that the grains had recrystallized form, as evidenced by numerous extinction contours at grain boundaries.
Besides, the anisotropy coefficient of the grain size amounted to 2.1.

With increasing the number of ARB cycles, Vickers hardness of the specimens increased and reached to a constant value.
It is obviously demonstrated that the grain subdivision[9] takes place with increasing the number of ARB cycles.
With increasing number of ARB cycles, density of high-angle grain boundary increases.
Number of cycles Vickers hardness, HV Fig.3 Change in Vickers hardness as a function of number of ARB cycles of the Al-0.2wt%Zr specimen.
Number of cycles 0 1 2 3 4 5 6 7 8 9 10 11 0 50 100 Fraction of HAGBs, fHAGBs(%) Fig.5 Fraction of high-angle grain boundaries (fHAGBs) as a function of number of ARB cycles in the Al-0.2wt%Zr. 5µm 5µm 50µm 5µm θ ≧ 15° 15°＞ θ ≧ 2° (a) (b) (c) (d) RD ND Figure 7 shows the grain boundary maps obtained by EBSD measurement of the ARB specimens aged for 360s at 623K or 723K, respectively.

Fig. 4 showed the average grain size on function of repairs number.
It is clear grain growth with the number of repairs.
It is clear that average grain size increases with the number of repairs, which in turn decreases the hardness.
Average grain size and Vickers hardness relate to average residual stresses in function of repairs number.
In general, the grain size increases with the number of repairs, however not clear tendency with the number of repairs was observed.

It was observed that the ultimate tensile strength (UTS) increased with increased number of passes.
On the other hand, the number of research works as to SPD of commercial medium carbon steels is still limited [9,10], probably because systematic SPD processing is relatively difficult in steels with higher flow stresses.
The warm ECAP pressing at 400°C was performed and billets were subjected to higher to number of passes, N = 4, 5, 6 respectively.
In deformed ferrite grains the parallel bands are formed in elongated grains, Fig. 3a.
Increasing number of passes to N = 6, (εef = 4), in the deformed ferrite grains the submicron grains with high angle boundaries were more frequently observed, as documented in Fig. 3b.

Relationship between Grain Growth and Formation of Fracture Surface of Ultrafine Grained Cu in High-Cycle Fatigue M.
In other words, oriented slip bands inside the areas increased their length and number with cyclic stressing.
Subsequent stressing brought a further increase in both grain size and number/length of slip bands.
oriantated grains.
Summary Marked grain coarsening occurred and slip bands were developed in the coarse grains.

The differences of elongation in three directions are related to the number and morphologies of M/A islands and the ferrites.
In this paper, the grain misorientations are used to identify grain boundaries and grain size.
However, the number of 1-2μm grains of the former is more than the latter, while that of larger than 2μm is less than the latter.
Furthermore, when the plastic deformation or cracks propagates through grain boundaries by one into another grain, the relatively more grain boundary of fine grains can effectively suppress crack.
The ratio of large-angle grain boundaries to small-angle grain boundaries at 90°direction is the largest.

Quantitative X-ray analysis of deformation microtexture within individual grains N.Yu.
Therefore, a set of MPF is available for an examined grain that is the basis for the following determination of the intra-grain ODF.
This set is presented by the L-dimensional vector of probabilities hPr determined according Eq. 2; L is the total number of p-cells throughout the set of the MPF used.
An obvious way to do that is to decrease the size of g-cell with respective increasing the number of the cells, N.
(8) Two main ways exist to improve the precision of the ODF determination: the increase of the dimension of the texture vector R and the increase of the number of MPF used.

For example, a number of reports on NC Ni with grain size from 30 nm to 100 nm have been reported [4-6].
And the reason for that is the same numbers of dislocation nucleated from GBs and annihilated at opposite GBs so that the amount of plastic carrier remains roughly the same during plastic flow process.
As a result a large number of stacking faults left in the grain interior (see Fig. 3(a)).
(a) In NC Cu, a large number of partial dislocations connecting with stacking faults are observed in the grains.
Also dislocations and stacking faults are smaller in numbers in the grains.

It should be noted that the ab-initio computations are currently limited to a relatively low number of atoms, on average less than 200.
Distribution function of the grain boundaries mis-orientation angle (a) and propensity of grain boundaries to grain boundary corrosion.
Change of grain boundary energy, in J/m2, due to alloying additions at the grain boundaries in aluminium.
A Molecular Dynamics Model of Curved Grain Boundaries Molecular dynamics is widely used in the modelling of engineering materials when a larger number of atoms need to be considered.
A model of the grain boundary geometry and their properties adopted in [24] - (a) Map of grain orientations and (b) grain rotation angles of boundaries for a structure with non-homogeneous grain size distribution.

It was therefore proposed to use FSW for grain refining of the parent material by putting a number of overlapping FS welds onto the edges of both parent plates prior to joining by fusion welding.
A number of technological measures have been evaluated in order to avoid liquation cracking of alloy 7085 EB welded joints.
Friction Stir Welding as Material Grain Refining Tool The results of metallographic examinations performed on a large number of alloy 7085 EB welds allowed it to be suggested that liquation cracking may be probably eliminated if the parent plate grain structure within the HAZ area could be changed from coarse into fine.
What was missing was a reliable method to provide such grain refining.
The EB weld, EBW / FSW boundary and FSW areas have fine grain microstructure.