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By EBSD analysis, it was found that crystallographic variant selection was observed not only across those prior α/α grain boundaries, but also within the α grain interior.
It can be found that many slip bands in a phase grains and bulk b phase accumulated in triple grain junctions.
The dark grey grains refer the a grains and the light grey grains illustrate the different Euler angles of b phase.
From Fig. 1, it is sure that the matrix is the a phase, and lots of random b phase accumulated along grain boundaries and within prior a grains.
And it is sure that the orientation of b nucleating from a grain boundaries and within a grains is best described by the K-S orientation relationship.

(4) where R is dendrite tip radius, Γ is Gibbs-Thomson coefficient, Pei is Peclet number, mi is liquid slope,C0,i is initial concentration, ki is partition coefficient, ζc(Pei) is function of Peclet number, Iv(Pei) is Ivantsov solution (where subscript i=Cr or Al), Ghkl is temperature gradient along the crystallographic orientation.
Three typical weld defects, severe stray grain formation, centerline grain boundary formation and asymmetrical solidification cracking, are simultaneously mitigated to improve weld quality.
Stray grain formation in welds of Ni-based superalloy CMSX-4.
Stray grain formation in single crystal Ni-based superalloy welds.
Analysis of stray grain formation in single-crystal nickel-based superalloy welds.

Rotation of grains leads to emergence of high local internal stresses.
Rotation of grains leads to emergence of high local internal stresses (fig.3).
So, high chemical activity of gallium turns this technological task into a sufficiently complicated process which depends on the number of both positive and negative factors.
Mass transfer of gallium into Al alloy between grain (SEM).
The diffusion results in an intense growth of grains sizes and volume of the detail, in shifting of old grain boundaries and formation of new ones.

At 400oC grain growth took place yielding a bimodal microstructure with mean grain size of 9 microns.
The grain size was reduced to 1.5 um and 9 µm respectively.
At 400oC the distribution is bimodal and grain boundaries are decorated with small grains indicating the process is controlled by dynamic recrystallization.
Smaller grains decorate the interface between larger grains.
These larger grains have a recovered inner structure and collars of small grains at the high angle interfaces.

Misorientation Effects on Grain Boundary Grooving of Ni by Liquid Ag P.
On the contrary, GB energies vary in a very wide range depending on grains misorientation and plane position.
Grain size about 100 - 200 µm was obtained.
Randle: The Measurement of Grain Boundary Geometry (IOP Publishing, UK 1993)
Nevertheless, the study of a large range of GBs geometry required the use of a great number of different bicrystals.

This process, grain growth, requires short-range transfer of atoms across the grain boundary.
(2) Here Nα and Nβ are the number of crystallographic orientations in the α- and β phase respectively, and the dependence of ϕα and ϕβ on space and time is suppressed as shorthand.
Four were with 500 α- and 500 β grains, and one was with 150 α and 150 β grains.
The white arrow on figure 3 points to an α grain surrounded by β grains.
The α grain pins the grain boundaries it contacts, while it diffuses through its neighbors.

Further, grain structure and grain boundary character are analyzed in detail to discuss the deformation mechanism.
Grain Structure.
They are distinguished by number of high KAM points.
Grain Boundary Character.
The fine grains remained during the deformation through grain boundary sliding or dynamic recrystallization.

Grain size and morphology results show that the compounds have clear grain morphology and also nanoscale grain sizes.
The uniformly grain growth and rounded shape grains with very clear surface morphology were observed.
It is obvious that MR values of nano-structured samples (NCMO & NBMO) will be higher compare to the bulk samples due to enhanced spin-polarized tunneling through the increased number of grain boundaries in nano-structured materials.
The grain size, structural symmetry and surface morphology can be governed by the calcination temperature.
The TEM and AFM results confirm that the nanoparticles of the NCMO & NBMO samples and grains are arranged in chains.

It is evident that the stronger ACB synthetic diamonds provide the maximal number of the cutting edges on the working surface of the grinding wheels.
The grain size of the diamond wheels has a significant influence on the forming of the roughness of the surface, since with increase of the dimension of the synthetic diamonds the micro-profile of the cutting surface of the wheel changes because of the reduction of the number of the diamond grains per unit working surface of the wheel.
With increase of the grinding wheel speed from 18 m/sec to 32 m/sec (vw = 25 m/sec; Sах = 10 m/min; Str =1.5 mm/stroke and t = 0.03), the parameter Ra decreases from 0.32 µm to 0.2 µm, which is associated with the increase of the number of the cuts by the diamond grains per unit time, and also with the decrease of the thickness of the cut that is performed by the individual grain, i.e., because of the specimens surface "sparking-out" effect.
The weakening of the bonds between the neighboring surface grains of the nitride ceramic leads to brittle fracture of the surface with the subsequent mechanical action from the active grains.
It was established that the specific number of the craters, the grooves, and the cracks on the surface of the specimens that are ground by the diamond wheel depends on the characteristic of the wheel and the grinding regime -and intensification of the grinding regime leads to increase of the number of these defects.

Optical microscopy was used to characterize the morphology of the aluminum grains, the dispersion of SWCNT and present pores in the samples.
The results indicated that the density and hardness of the samples are increased with the increase in the number of extrusion passes and the use of back pressure.
The factors investigated were: the presence of CNT; the number of extrusion passes; the extrusion route used between passes; and the use of back pressure.
The ECAE passes in route A of the sample promoted the alignment of aluminum grains and CNT clusters in the direction of extrusion.
The refinement of CNT clusters occurred similarly to the grain refinement.