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The important properties studied are moisture content, total clay content, grain fineness number, and grain shape.
Results obtained revealed that the river sand has average moisture content of 7.78 %, clay content of 3.20%, and grain fineness number (GFN) of 46.
Most mold sands should fall within 50-60 grain fineness number (GFN) or 220-250 microns average grain.
The grain distribution for each samples were obtained and the Grain Fineness Number (GFN) was calculated using the equation: GFN=Wn x SnWn (3) Where Wn is the weight of sand collected on each sieve and Sn is grain fineness coefficient.
This number classifies it under coarse grain size, which is still within the acceptable range of mold sand and suitable for metal casting application [7, 10, 14,15].

Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.
Grain boundaries at the area of 227μm×174μm are outlined using IPP software, the grain equivalent diameters are measured and the number of grains is counted.
Statistical analysis for grains size and numbers in metallographic image is shown in Fig.8.
With the increase of cutting speed, the numbers of large grains and medium grains continue reducing while the small grain numbers increase in FGH95 alloy machined surface.
With the increase of cutting speed, the number of large grains and medium grains continue decreasing while the small grain numbers increase for machined surface of FGH95 superalloy.

However, after 5 cycles, grain growth occurred.
The reduction of the grain size after the ARB process proves the effectiveness of the process in the alloy; however, the re-growth of the grains with further cycles indicates that there is an optimum number of ARB cycle under the process conditions.
The low wear resistance of the ultra-fine grained Al alloy was attributed to its non-equilibrium and unstable grain boundary characteristics.
Wear rate vs. number of ARB cycles for 6061 aluminum alloy. 0 1 2 3 4 5 6 7 0 10 20 30 40 50 60 70 80 Wear Rate (1x10 -13 m3 /m) Number of Cycle Applied load : 1N Applied load : 2N Applied load : 4N Fig. 4.
Wear rate vs. number of ECAP passes for AZ61 magnesium alloy. 0 2 4 6 8 0 2 4 6 8 10 12 Applied load : 3N Applied load : 5N Applied load : 7N Wear Rate (1x10 -12 m 3 /m) Number of Pass

Introduction The triple junction of grains is a linear defect, along which three variously oriented grains or three grain boundary surfaces are conjugated.
The grain boundaries are denoted by the bright dashed lines.
The grain boundaries are marked by thick gray lines.
As a result of rapid cooling, a large number of defects formed in the calculation block in addition to the grain boundaries: pores, vacancies, dislocations, disclinations.
The reason for the formation in polycrystals a large number of the strained triple junctions having a relatively "loose" structure with a high share of the free volume was elucidated in the study of crystallization in the three-dimensional molecular dynamics model.

A number of special boundaries form preferentially during solidification, and those with misorientations about a [110] axis, including low angle boundaries, are more likely to slide with thermal cycling.
Tin has a number of important forms of anisotropy that complicate its deformation behavior.
Since tin is tetragonal, it has a number of slip systems with different Burgers vectors and slip planes [10, 11].
Grain Boundary Sliding in Pure Tin.
After substantial grain growth, the large grain size led to greater amounts of shrinkage during cooling in grains having the c-axis more nearly aligned with the ND, which is most evident in the ledge along the lower (dark gray) grain at the bottom of the image.

Fig. 3 shows the corresponding morphology of austenite grains.
When the strain increases to 0.3, which corresponds to the peak stress, many dynamic recrystallization grains occur at the prior grain boundaries with zigzag shape, which refine the austenite grain size.
When the interruption time increases to 10 s, quite a number of newly formed austenite grains appear around the prior grain although some grains seem to be nucleated just at the quenching time.
With increasing the holding time, the newly formed austenite grains grow inside the prior grains and impinged each other, which leads to relatively small and homogeneous grain size (Fig. 5c).
Average grain size after held for 50 s is about 28μm, which is much smaller than the prior grain size.

In this study, the STSP is applied to grain refinement of an A5056 Al-Mg commercial alloy and the factors affecting the grain refinement are optimized.
The grain size tends to be smaller as the STSP temperature decreases: the average grain sizes are ~1.5 µm at 673 K, ~1.9 µm at 723 K and ~3.1 µm at 773 K.
The former leads to insufficient numbers of dislocations to create grain boundaries and the later makes it difficult to keep the grain size small.
Figure 6(a) shows that the microstructure at the slow cooling rate consists of fine grains and large grains with the average large grain size of ~5.5µm.
The SAED pattern indicates that the fine grains can be separated by high angle grain boundaries.

Grain boundary sliding.
Figure 1.h shows the grain boundary offsets that occur in grains orientated at an angle offset to the tensile direction, with the early start of accommodation by surface grain separation or grain emergence.
This was observed across a number of grids, as well as at various locations on the surface that had not been FIB milled.
Again, this was exhibited across a number of grids, and in surface areas not FIB milled.
The number and size of these defects were believed to vary with strain-rate.

Higher microhardness numbers were generally found near the casting surface, at the corners and along the segregation band.
The majority of lower hardness numbers was found at the core region.
A few very low hardness number points, in the range 30~45 Hv, were also found in the core region.
Many of the highest hardness number concentrate at one of the corners in Fig. 1-a.
Dendritic grains appeared dispersed in the surface and corner regions as well, although they were much fewer in number than at the core.

Introduction It is generally observed that the solid volume fraction and interface energies play an essential role in the morphological changes during sintering and determine directly parameters such as grain shape, grain-grain contact size and shape, grain coordination, contiguity and connectivity [1].
,ηps,s, is used to represent the different grain orientations of the solid phase particles, with ps the number of phase-field variables representing the solid phase, and one extra non-conserved phase-field variable, ηl, is used to represent the liquid matrix phase.
Later, the overall grain boundary area is further decreased via grain growth and Ostwald ripening.
It is related to the 3-D coordination number Nc and dihedral angle φ as [1] Cg = KNc sin(φ/2) with K a constant related to the grain size distribution.
The 3-D coordination number for each simulation is obtained as the average particle-particle contact number per particle from 3-D microstructure.