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In spite of the large number of papers dedicated to different aspects of SPD-processed aluminum alloys, a little effort has been directed towards elucidating the influence of the combined effect of the deformation mode and second phase particles on the microstructure refinement, and on the influence of ultrafine-grained structures close to large particles on early stages of recrystallization.
At this stage the grain size was 40-60 μm.
(Size depends on the applied number of passes.)
This lead directly to fine grain structure.
As for the recrystallized grains, some preferences in the selection of grain orientations were observed.

In common grain growth processes the main driving force for grain boundary motion comes from a lowering of the system’s Gibbs free enthalpy.
We do not allow the number of grains to change (thus no topologically changes) nor do we allow quadruple junctions to move.
Thus, the optimum number of smoothing cycles is found just after the steep exponential decay.
For this particular example the optimum number of smoothing cycles is between 10 and 20.
b a Fig. 4 a) Grain from Fig. 2a in tilt-twist coloring. b) Normal distribution of grain boundary indicated by arrows in a).

The different heights are numbered n, m, etc.
Results Grain orientation - texture.
The drop in the relative efficiency is about 5 % when going from grain A to grain B.
Grain boundaries.
Sub-grain boundaries are not presented.

However, the number of studies concerning the recrystallization and transformation behaviour in the conditions of fast reheating of cold rolled steel sheets with heating rates higher than 100°C/s is limited [3-6] and they consider the recrystallization of iron [6] or extra low carbon steels [3] after reheating with a reheating rate of 1000 °C/s [3] or 5000 °C/s [6].
The averaged grain size was evaluated on the base of the EBSD measurement considering as a grain each contiguous region with a misorientation of less than 5° and containing more than 4 pixels.
The grain size is strongly dependent on the reheating rate as it is demonstrated in Fig. 5 and Fig.6.
The dimensions of the largest grains are shown.
The grain size of ~1 µm is obtained in ultrafast reheated samples in the temperature interval 790-880°C but the question for grain growth in isothermal conditions after ultrafast reheating still remains to be investigated.

In the as-pressed condition, the microstructure was reasonably homogeneous and the grain size was reduced to an ultrafine grain size of ~0.3 µm.
This alloy contains MgZn2 and Al3Zr precipitates which restrict grain growth.
First, there must be a small and stable grain size, typically less than ~10 µm.
Summary and Conclusions (1) A spray-cast Al-7034 alloy with an initial grain size of ~2.1 µm was processed by ECAP to reduce the grain size to ~0.3 µm.
Langdon, Ultrafine Grained Materials III (Y.T.

The size of grains and the crystal phase of copper oxide were controlled by the number of ALD deposition cycles.
As the number of ALD cycles increases to 750, the small grains become larger and merge with each other, as observed previously in the ALD growth of TiO2 on mesoporous Si [35] and TiN on SiO2 [36], or ZnO on InGaAs substrates [37].
The size of the copper oxide grains increases with the number of ALD cycles while, at the same time, the stoichiometry changes from predominantly CuO for small numbers of cycles to Cu2O for larger numbers.
In addition, for the small number of ALD cycles, the nanosized copper oxide crystallites are dispersed over the TiO2 surface (with the preferential nucleation sites at the TiO2 grain- boundaries), while larger grains of copper oxide cover most of the TiO2 surface for the larger number of cycles.
However, when copper oxide grains cover the most of TiO2 surface (750-cycle sample), the photocatalytic activity is greatly reduced, reflecting the reduction of the number of active TiO2 sites on covered surfaces.

A number of studies have shown that alloying additions of rare-earth (RE) elements to Mg alloys result in a significant weakening of the basal-type texture [1-3].
Rolled sheets of Mg-RE alloys show a large number of contraction- , secondary twins as well as high activity of pyramidal slip, processes which are seldom observed in pure Mg and conventional Mg alloys, such as the AZ alloys.
An analysis based on the in-grain misorientation degree was employed to evaluate the area fraction of the recrystallized grains.
RD ND grains with an in-grain misorientation smaller than 0.5 ° are supposed to be recrystallized.
The recrystallized grains in the sample annealed for 5 s have an average grain size of 7 ± 2 µm, whereas the average grain size of the sample annealed for 3600 s is 54 ± 19 µm.

Grain refinement using master alloy is a very good method.
And the number, the size cannot compete with those in the static cast.
Consequently, improved the grain refinement.
And grain refinement using ATB is disabled.
The result of grain size obtained by differently intense stirring show that dendrite breaking should be the mechanism of grain refinement.

The microstructure was effectively refined with increasing the number of CEC cycles as the grain size was reduced from ≈250µm to ≈30 µm after 6 cycles of CEC.
Microstructure Analysis Coarse equiaxed grains with ≈250 µm grain size were observed in annealed specimen, Fig.3, which represents the initial condition samples for CEC.
With increasing the number of cycles the macrohardness increased with a lower rate up to 6 cycles reaching about 2 times the hardness of the annealed alloy.
The improvement of the hardness value of the CECed samples is mainly due to the grain refining and work hardening in the material with increasing the number of cycles.
Summary · As the number of CEC cycles increases a more homogeneous grain structure with reduction in grain size from 250 µm to 25 µm

As the cycle number increased, the pattern of the grains began to lose contrast, with the higher grains becoming sharper, distorted and thus looking more like crests.
The white and black dotes have been superimposed on the images to help finding identical grains in the two images In Fig. 3 to Fig. 5, a number of statistical values obtained from the same interferometry data as used to form the images in the previous figures are presented.
They exhibit small peaks and, for the same area analyzed, the wavelength remains essentially the same, irrespective of the number of cycles.
Arrows indicate steplike rumpling pattern associated with grain boundaries Discussion The observations of rumpling between different intermediate temperatures and 1150 o C and the dependence of the rumpling magnitude on the number of cycles is similar to that previously described by Tolpygo and Clarke [2].
At the grain structure level, the stress may be different according to the size of the grain.