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Misorientation and spacing of high-angle boundaries decrease with the number of passes.
This is interpreted as a result of the tendency to form equiaxed grains in a textured grain structure.
This has to do with the strong shearing of the grains transforming equiaxed grains into elongated ones.
F increases by 1/N (N: number of measurements) whenever φ equals a measured value φi.
It is seen from Figure 3 that the misorientation distributions F(φ) of (even-numbered) passes 2n are generally quite similar to those of the preceding (odd) passes 2n−1.

The base metal microstructure consists of large elongated grains (Fig. 3 (A)), with an average grain thickness of 25 µm.
As it can be seen, by increasing the number of FSP passes the cluster size is reduced and the distribution of the Cu particles is improved.
The average grain size of the composites is listed in Table 1.
Results indicate that the average grain size is reduced by increasing FSP passes and the specimens produced by SQ tool have smaller grain size compared to the specimens produced by the SC tool.
Increasing the number of FSP passes decreases the clustered Cu particles, improves the distribution of Cu particles and creates a homogenous SZ with smaller grain size.

In the process of grain refinement through phase transformation, driving force and the parent phase grain size are two key factors.
From this Figure, there are some austenite grains with the grain size about 3~6μm and the other austenite grains are pretty small, the mean grain size of all the austenite grains is about 1~3μm.
The number of quenching cycles also affected the austenite grain size.
Most of the observed areas were filled with the equiaxed ultrafine grains whose grain size is less than 0.3μm.
The ultrafine grains are surrounded by clear grain boundaries.

The columnar grain zone is very significant and there are a small amount of equiaxed grains.
With the increase of feeding ratio, the columnar grain zone becomes smaller and smaller, the equiaxed grain zone becomes larger and larger, and the grain size in the equiaxed grain zone decreases continuously(Fig.1b and 1c).
Table 3 The influence of feeding ratios on the solidification structure at 30 K Number of casting ingot Feeding ratio/% The area proportion of equiaxed grain zone/% The average size of equiaxed grain/mm 1 0 38 10.2 2 0.24 48 8 3 0.96 68 4.5 Steel strip-feeding changes the temperature distribution of molten steel in the crucible, and reduces the superheat degree and the temperature gradient.
The number of crystal nuclei decreases.
So, the proportion of equiaxed grain zone decreases, and the average size of equiaxed grain increases.

Hence, the region near grain boundary flows plastically prior to the matrix.
Therefore, the dislocations concentrated near the grain boundary.
The propagation of dislocations to the matrix is easiest when the maximum shear stress in grain is parallel to longitudinal grain boundaries by applying the external stress in the 45° direction of elongated grain structure.
The diminishing of yield strength anisotropy in peak-aging condition could come from increased number of operating slip system near the grain boundary regions with PFZ.
Acknowledgements It is a project supported by natural science foundation of shanxi province China (project number: 2009011028-1; 2011011021-1).

For diffusion creep n = 1.0 whereas n is frequently close to 2 for grain boundary sliding (i.e. superplastic regime), both mechanisms being promoted by a grain size reduction, the value of p varying from 2 when lattice diffusion is controlling or 3 when grain boundary diffusion is controlling.
Thanks to such analyses, various data like the volume fraction of cavities, the size and shape distributions of the number of cavities per unit volume can be measured in in situ conditions.
Figure 4 displays the variation with strain of the number of cavities as well as 3D observations of the population of cavities for two strains: ε ≈ 0.13 and ε ≈ 0.35.
A continuous increase of the number of cavities is detected and values of several thousands of cavities per mm3 are measured.
The 3D observations of the population of cavities confirm clearly that the number of detected cavities increases significantly with strain.

High pressure torsion extrusion (HPT) under pressure in 6 GPa, with the number of revolutions n = 1 and n = 10 at room temperature, carried out on the installation « SKRUDZH-200».
Results and Discussion Table 2 presents the results of microhardness evaluation (HV0,05) and medium grain size (dL) samples of alloy D16 in the initial state, after HT (Т4, Т6), and HPT under pressure in 6 GPa with the number of revolutions n= 1 and n = 10.
Coarse grain α – solid solution, Fig.1,а were separated by dislocation walls, i.e. under HPT, the formation of small-angle sub-grain boundaries occurs within a single grain, as evidenced by the blurring of reflexes α – solid solution on electron diffraction patterns, Fig.1,b.
As can be seen from the table 3, with an increase in HPT revolutions, the number of intermetallic reflecting planes increased, which is probably due to their grinding, an increase in the number of possible orientations and an increase in the volume fraction of phase boundaries, as well as an increase of 1,3 times the hardness due to dispersion hardening (Table 2).
Scientific Reports. 2018, 8, Article number: 8454

The dressing progress is quantified by the cumulative collision number id, representing the number of collisions of the engineered grinding wheel grains with the abrasives of the dressing wheel [9].
The specific force values show a linear trend for all grinding wheels due to the increasing collision number id during the dressing process.
Additionally, the surface roughness values Sa and Sz show a clear correlation to the collision number id of the Engineered Grinding Wheels.
The surface roughness decreases with increasing collision number id because the cutting mechanism turns into ductile removal (figure 3, right).
In comparison, the surfaces ground with conventional diamond grinding wheels show a high number of outbreaks.

In a number of areas of engineering practice, alloying may be unacceptable, for example in medical materials for reasons of biological compatibility, or undesirable, as in nuclear materials due to deterioration in functional properties and the need for long-term tests when putting into operation of new material.
In recent decades, great progress has been made in obtaining materials with ultrafine grain.
In an effort to use grain refinement to increase the yield strength and strength of metal materials, various technologies for producing fine grains of polycrystalline aggregate were developed (see, for example, reviews [1-5]).
This made it possible to obtain metal materials with virtually any grain size up to 100 nm or less.
Conclusion The SLM method makes it possible to form an ultrafine-grained structure.

The average grain size varied between 0.1 and 0.2 µm.
On the right the calculated energies per H atom of a number of H complexes in c-Si are show [11,12].
Defect passivation requires only a small fraction of H atoms, which is equal to the number of passivated Si dangling-bond and amounts to about 3.7×10 18 cm-3.
Platelets neither penetrate the sample surface nor grain boundaries because of band bending caused by high concentrations of surface and grain-boundary defects [16].
Therefore, its formation is restricted to intra grain regions.