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Such nanocrystalline electrodeposits are in thermodynamically non-equilibrium (metastable) states, i.e. high energy states due to a large number of interfaces [8-10].
Since nanocrystalline materials are in high energy states due to a large volume fraction of the interfacial components such as grain boundaries and triple junctions, the driving force for grain growth is so large that the grain boundaries can move far below temperatures at which grain growth is expected to occur in coarse-grained materials.
Gray-colored grains indicate the <100>//ND grains.
The activation of grain growth may depend on the crystallographic orientation of each grain as-deposited, and it is obvious that the growth rate of the <111>//ND grains is highest.
Thus, what should be explained is why the abnormal grain growth occurs selectively for the <111>//ND grains.

Then the size of austenite reduces because the number of austenite crystal nucleation is larger [5].
After measuring the grain size, the averaged value was the grain size.
The grain size curves under four different strain rates Dimension of the grains/mm . 4.
Because there is non-homogeneous nucleation in grain boundaries, new grains generate in the grain boundary continuously.
So these fine equiaxed grains occur only in the grain boundaries.

Methodology As the first step in MPF method a system with certain number, N, of different PF, f1, f2, f3, …fN, is determined.
By using step function, number of local phase, n, is defined as
PF evolution is explicitly defined as: (4) where i, j and k are number of local grain from 1th to nth at the numerical grid, and subscript x and y refer to derivation on the x and y axis.
It can be seen from the figure that all grains move forward without significant grain growth on the side direction of each grain.
At the end of simulation processes, only several grains with high orientation angle exist and experience grain growth while low orientation angle grains either diminish or exist as small grain (second grain from the right).

The adjacent boundary between one grain and another is called grain boundary.
PTh is the ratio of those pixel number with gray level less than and equal to Th1 to S
In this figure, 0~7 stand for the numbers of eight directions, that are direction codes.
The total number of related pixels on these chains is PB (=1798 pixels).
Additionally, the direction code is just one of eight numbers from 0 to 7, and it can be encoded by 3 bits.

A comparative study on the wear behavior of cast and forge aged A356 alloy with addition of grain refiner and/or modifier D.
aemail: drmallapur@yahoo.com Keywords: Forged A356 alloy, Grain refinement, Modification, T6 heat treatment process and Wear.
It could be conceived that forging process creates large number of micro voids, particularly at the interface of brittle silicon phase and ductile aluminium matrix.
In addition the frictional force is always lower in grain-refined and modified alloys and this is due to the fact that, strength and hardness of the alloy improves with the addition of grain refiner and modifier.
Addition of grain refiner leads to decreases in the grain size and results in the formation of more number of grain boundaries.

Wear characteristic of SFAT presented mostly blockage and little grain-off occurred in dry status; mostly grain-off and little blockage presented in wet status.
It conceived that a tool as general grinding wheel composed of abrasive grains, pore and bond material, but the bonding strength is weak enough that, when a large grain enters the machining area (the gap of workpiece and working area of the tool), the abrasive grains near to the large grain will move to form accommodating space for the large grain and trap it in.
The load is not carried by a small number of large grains, but by a large number grains including the large one.
Material removal rate was gradually decreased in the fore 30 minutes, from 40 to 60 Porosity Bond Grain Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Truer Grain Non-work area SFAT work area water minutes; material removal rate had little changed.
While SFAT in wet status lapping wafer, debris number that embedded into the work area were not as much as that in dry status, a large number of grains would be carried off SFAT surface by water, material removal and surface roughness remained little change.

Several methods to obtain fine crystal grains have already been proposed.
The plates consist of fine crystal grains with a preferred orientation.
Compared with a sample formed under single axis compression, the sample formed by dynamic molding possessed a Vickers hardness number that was about 2.4 times larger (27 versus 66 Hv).
In addition, the Vickers hardness number of the molded sample was about 1.9 times larger (35 versus 66 Hv) than that of 1060-H18 aluminum, which is dissolved and treated by work hardening.
In addition, it became clear that each crystal grain is a single crystal.

Fig. 2 Microhardness as a function of number of CECC pass.
A large number of low angle boundaries (LABs) are also observed in the interiors of grains (Fig. 4 (a)).
Some areas have elongated grains containing large number of LABs.
Fig. 6 Volume fractions of the fiber textures as a function of number of CECC pass.
With the increase in the number of CECC cycle (effective strain), the efficiency of grain refinement will be limited [20].

Modeling of Heat and Solute Interactions upon Grain Structure Solidification Ch.
Due to the small value of the Biot number, the temperature could be assumed uniform in the thickness.
Figure 6 presents the simulated grain structure.
The grains appear much coarser than the experimental grain structure.
In the simulated grains structure, after nucleation in the undercooled liquid, grains remain fixed in space and can only grow.

The grains visualized through optical microscope consist of an average grain size of 115 µm indicating homogeneous and equiaxed grains.
(b)-(d) provides the micrographs of cryorolled samples and with the increase in strain, the grains become elongated and the evolution of sub grains within the grains occur.
In addition, distinction between the grain boundaries and grain interior is difficult due to severe fragmentation of the grains.
With the reduction in grain size, the grain boundaries rose up leading to grain boundary strengthening according to Hall-Petch equation.
There is presence of dimples which is evolving in number and some micro cracks is also visible with the help of SEM due to reduced grain size by processing of cryorolling.