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The number of elements in the mesh is 4200 and the shape of element is quadrangle.
The change of copper grain size.
But in general, the copper layer is composed by united grains and the grain size is about 4μm.
We also know if steel is hardened by laser and its temperature is up to 1300 K, a large numbers of acicular martensite will be observed[14].
In Fig 8(b), the number of twins is not so much and their orientations are random.

Fine grain does not appear while the columnar crystal directly grow from the combination layer.This is different from the fine grain zone of the surface, columnar grain zone, equiaxed grain zone which are all formed during being casted.
This is when the laser clads, hexagonal structure α(Mg) solid solution of zone A and Mg matrix are fully coherent, while during the cooling process the grain grow directly as unmelt solid grains of the substrate surface as the nucleation center ,but limited number of the matrix grains result in a coarse columnar grains.
Massive dark figure is Mg2Si phase (a smaller number) by electron spectroscopy (EDS) analysis, we believe it reach zone B by convection and gravity.
Microstructure characteristics shows that a large number of dendrites located in the zone C.According to Electron Spectroscopy (EDS) analysis of figure 5, the coarse dendrites are Mg2Si phase and matrix is mainly β (Mg17Al12) facies.The molten Mg is reacted to Si of Al-Si eutectic alloy in zone C, then a large number of Mg2Si coarse dendrites is formed.
During the cooling process the melted Si separate out in the grain boundaries make the grain boundary coarsening.

The determination of time-dependent grain shape and grain size (i.e. grain coarsening), as well as coordination number distribution is presently the most challenging task in the application of solid skeleton (network) models for predicting the mass transport during LPS.
In analysis of 2-D grain coordination number (connectivity) against the measured distortion for various alloys it was found that the critical connectivity required to maintain structural rigidity was 2 and 3 in gravity and gravity environment, respectively [60,61].
As the 3-D nearest neighbors search algorithm we will apply simple method for computation of nearest neighbors ordinal numbers vector.
After 120 min (Fig. 12(b)) the number of skeletons was slightly increased to 6 skeletons with 8 bonds.
Although the number of solid grain contacts after 180 min (Fig. 12(c)) is greater than after 120 min, it can be seen that even after long sintering time the skeletal strength is reduced.

Whenever all grains have the same properties and the strain rate is uniform, every grain's history is the same, which leads to simple analytical calculations.
Eq. (3) means that any grain gives rise to one single grain during its life during the steady state.
Since a number of publications, including the original Derby papers [6], suggested , this led the present authors to choose in their DDRX model [1,2].
Cahn, The impurity-drag effect in grain boundary motion, Acta Metall. 10 (1962) 789-798
Derby, Dynamic recrystallization: the steady state grain size, Scripta Metall.

The results show that the grain size is affected by the spindle speed.
Increasing the number of passes reduces also the size of the grains and the intermetallic phases in the AZ91 alloy.
The alloy in as-cast condition showed α-grains of about 500µm size and intermetallic phases in different forms at the grain boundaries.
The α-grain size was similar for both rotation speeds, with an average grain size of 6µm.
During process at 900rpm/30mm.min-1 the α-grain size varied from 400nm to 2µm, while the β-intermetallic phase was refined (grain size max. 600nm).

They also suggested that significant dynamic recovery and recrystallization occurred during the deformation process, resulting in a large number of grain orientations with very little texture.
It indicates a weak texture and a large number of orientations present.
For comparison, average grain size of as-received arc-melted buttons is less than 200 µm. 0 100 200 300 400 500 600 700 800 900 800 900 1000 1100 1200 Rolling temperature (°C) Average grain size (µm) Fig. 5.
Average grain size as a function of rolling temperature, at a total reduction of about 80%.
These results also suggested that significant dynamic recovery and recrystallization occurred during the deformation process, resulting in a large number of grain orientations with very little texture.

As shown in Fig. 3, the as-forged Ti-47Al-2Cr-2Nb-Y alloy has refined streamline microstructure along radius direction composed of a large number of recrystallized grains and a small amount of retained casting lamella colonies.
At high temperature, disordered β phase could provide a sufficient number of slide systems and carries most of the deformation [7, 15].
This overcomes limited number of slip systems of the room temperature deformation in TiAl based alloys.
Strain compatibility among different grains is also improved.
Disordered β phase with bbc lattice provides a sufficient number of independent slip systems, which improves tensile properties.

Natural gold microstructure results Mako QP’s gold microstructure is characterised by a bi-modal grain size, with small grains up to 100 µm in size and large grains over 200 µm in size (Fig. 1A).
The external shape of the gold grains is extremely irregular, regardless of size, whereas the high angle grain boundaries (HAGB) within gold grains are regular, either straight or curved (Fig. 1A).
The gold grains exhibit a preferred orientation of lattice bending (misorientation <2°, shown as changes in the colour inside the grain) and low angle grain boundaries (LAGB) <10° (Fig. 1A).
(A and C) Greyscale changes correspond to orientation changes of the gold grains (internally and between grains).
[7] Lloyd, G.E., Atomic-number and crystallographic contrast images with the SEM - a review of backscattered electron techniques, Mineral.

F1=Fm+Fg+Fa+Fτ F2=Fd F1=F2 (3) The grain size depends on the number of nucleation.
The more nuclear number, the smaller sizes of grains.
The distribution of bubbles is affected by the number of nucleation and crystal growth[16].
Based on the relation, to build three kinds of models as follow: Model A: The large number of nucleation would decrease the average grain size, so that the distribution of nucleation around the bubbles is dense (Fig. 6(a)).
Model B: when the number of nucleation is low, the average grain size is big.

Compared with the low-nitrogen steel, the number of precipitates in decreased significantly and the size increased obviously in the high-nitrogen steel.
Besides, a small amount of 90~260nm irregular particles distribute on the grain boundary.
Nearby the high energy grain boundary, the dislocation density is high.
The number of precipitates was obviously decreased, and the size of which was larger than that of low-nitrogen steels.
Ultra-fine Grained Steel-Theories and Technologies of Structure Fined[M].