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In a number of studies [4,15–18], twinning was observed at a fist stage of nucleation and continued to develop during the grain growth until the completion of recrystallization.
The number of Σ3-twin boundaries increased greatly (Fig. 3 g-m) to the end of the recrystallization.
The number of special boundaries Σ3 decreased insignificantly and it was due to HAGB between the grains, while the Brandon criterion decreased 5 times.
The role of special boundaries having a large number of coincident sites during recrystallization of FCC metals is described in [6].
Thompson, A comparison of grain boundary evolution during grain growth in fcc metals, Acta Mater. 61 (2013) 3936–3944.

Compared with scattered abrasive with the same number grains, the removal rate is less.
The number of cracked dings in the workpiece surface decreases and the surface roughness become little to a certain value.
The number of cracked dings in the workpiece surface is little, the roughness rapidly decreases and become nearly unchanged at last.
When the grain size is big, high speed is chosen.
Grain type and grain size of polishing film.

On its basis the SAR number values for all investigated materials were calculated.
The SAR number values for the alumina matrix and composites.
The wear proceeded not only by the alumina grain crushing, but also by the weakening of grains boundaries and the removal of whole grains as a result.
In effect whole grains or grains agglomerates could be removed.
This counteracts rapid grain boundary erosion.

Heavy deformation was introduced in the samples after a considerable number of ECAP passes, from 1 to 16.
The number of ECAP passes, namely 1, 4, 8, 12 and 16 promotes a significant grain refinement observed by transmission electron microscopy (TEM).
Fig. 2 Longitudinal wave velocity vs. the number of ECAP passes for nanostructured copper.
Fig. 3 Transversal wave velocity vs. the number of ECAP passes for nanostructured copper.
A bimodal grain size distribution developed for higher number of passes.

The grain size was determined by the average grain equivalent diameter d2.
In all the samples, the average grain size determined on transverse sections was about 70 nm and the nano-grains in the various regions of the rods were similar in the shape.
Samples cut for TEM studies and microhardness measurements Results and Discussion The homogeneity of the bulk nanocrystalline titanium was examined in two HE-produced rods that differed by their diameters, applied strain and the number of the extrusion passes.
The grain size distribution in the Ø7 mm rod: a) top, b) end a) b) Fig.6.
The grain size distribution in the Ø10 mm rod: a) top-centre, b) top-surface Figures 5 and 6 show examples of the grain size distribution determined in various regions of the Ø7 and Ø10 rods.

The maximum cutting depth (agmax) of single abrasive grain is obtained by 21 max 4 � � � � � � = ep ds w g da CN a � � , (2) where �w is the feed rate, �s is tangential speed of the wheel, Nd is the number of dynamic effective cutting edge, C is the cutting constant, ap is cutting depth and de is the equivalent diameter of the wheel.
The number of the dynamic effective cutting edge (Nd) is the measured effective cutting edge on the unit area along the contract arc of the wheel and the workpiece.
In actual situation, the exponents � and � are related to exponents p and m. p reflects the relationship between the dynamic cut-in depth ads and the number of static effective cutting edges of unit length.
(9) When m=0, it means some grains are blunt and while m=1, it shows the triangle grain.
Acknowledgements Author gratefully acknowledges Heilongjiang Province Natural Science Foundation and the Harbin City Science Foundation of China Heilongjiang Province for their Support of this work: The contact number is E0218 and 2002AFXXJ046.

Novelty of this technique is one can build up significant amount of plastic strain by increasing the number of passes without much dimensional change.
Hence, the mechanical properties of Al-Li alloys are primarily dependent on grain size, nature, volume fraction and distribution of precipitates, both within the grains and at the grain boundaries and occurrence of precipitate free zones (PFZ).
Usually, a single grain is found to nucleate at any particle at the maximum.
These recrystallised grains were estimated to be in the size range from 20nm to about 100 nm.
It is suggested that with the assistance of non-deformable particles, it might be possible to get ultra- fine/nano-crystalline material through ECAE with relatively lesser number of passes.

For example, the grinding wheel wear is attributed to bond fracture, grain fracture, and attritional grain wear [1].
The result of grain shape measured using the SLM is shown in Fig. 2(b).
The obtained result yields a shape with clearer features of the measured grain.
The extraction method fails to approach the grain boundary in the cases that many pixels have the median value, there is a gap at the boundary between the grain and the bond, or the grain tip is far from the grain centerline.
The shape processing approach is applied for a number of grains and the obtained results are employed for measuring three angles on each prospective cutting edge of the measured grain.

In reference[4], factory experiment showed that the ratio of equiaxed grain zone and the equiaxed grain density all decreased with increasing casting speed.
By this way, the propagation of grain occurs.
In this study, casting speed is the only variable, hence we assume that the number of the original separated grain is the same at different casting speeds.
As a result, the value of H (Formula 6.) is chosen as the measurement criterion of the number of the heterogeneous nucleation nucleus.
In this situation, the number of the survival separated grain which can become the heterogeneous nucleation nucleus finally is greater.

We defines the recovered fraction of aluminium grains as frc and the recrystallised fraction as frx.
Grain growth.
Also, krx points to the predominance of Al-Sn phase boundaries, while grain growth is characterised by the increase of Al-Al grain boundaries.
These results indicate that a model based on grain growth alone is not accurate.
However, even the simplest physically-based model tested here resulted more accurate than the polynomial fit, with a smaller number of adjustable parameters.