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Although a great number of researches on Al-Cu alloys have been done, little research on improving mechanical property by the centrifugal force field is reported.
This is because with increasing the centrifugal radius and mould rotation speed, grain size decreases, and the variation amplitude of grain size increases [8].
When the dislocation glides from one grain to another, it is hindered by grain boundary resulting in pile-up of dislocation.
The finer the grain size, the higher the grain-boundary density so that the above hindrance role is greater and the casting is harder.
Moreover, the finer the grain size, the more the number of grain.

Fig. 1 Microstructures of ZW61 alloy (a) as-cast, (b) hot extruded and (c) 8 passes ECAE processed Some large grains disperse in the matrix with small grains and a small number of second-phase particles of Mg3YZn6 (i.e. the dark particles) scatter along the grain boundaries.
In addition, a large number of strips oriented in the extrusion direction are present (Fig.1 (b)).
Lots of recrystallized small grains and some coarse grains are observed.
Liquid, indicated (c) (a) (b) by the presence of Mg3Zn6Y particles after quenching, has appeared both along grain boundaries and as tiny liquid pockets within the grains (Figure. 2 (a), (b) and (c)).
Obviously, with the increasing temperature, grain coarsens evidently.

Grain boundary precipitation is also not modelled.
Precipitation on grain boundaries The growth of grain boundary precipitates is modelled considering a collector plate approach [8,9] to account for the fact that precipitate growth rates at grain boundaries are too fast to be explained by volume diffusion alone [9].
Grain boundary and PFZ size evolution in the HAZ.
Evolution of a) homogeneous η volume fraction evolution with volume fraction of dispersoids, b) final η volume fraction in the matrix and on dislocations with varying dislocation number density, in the HAZ for 7449UA FSW.
A number of unknown physical parameters were calibrated using a combination of experimental techniques.

The ferrite grains are elongated to a certain extent along the cold-rolling direction.
It is clear from Fig.5 that the grain size distribution of sample A is much more uniform than that of sample B in which there is a large number of fine grains about 2µm.
While for sample A, since it suffers from CSCR, the average grain size of martensite is close to that of ferrite, and thus there are not a large number of fine grains, which agrees with the observation of SEM shown in Fig. 3a.
Fig.5 Grain size distributions determined by EBSD.
The fine average grain sizes for both samples A and B result from the addition of Nb refining the original austenite grains.

Green carborundum abrasive grain with grit number #800 was selected by the consideration of the balance between surface roughness and removal rate.
If all abrasive grains have sphere shape with diameter in a 20 µm and uniformly arranging on the machining surface, the applied load on one abrasive grain can be calculated as over 200 mN when the lapping pressure is 61.6 kPa with the general slurry density (5 wt%).
This change of groove pattern could decrease the slurry density because of an increase in the number of groove which is source of abrasive grains.
A cup type metal-bonded diamond wheel with grit number #200 was used.
Conclusion After the deformation characteristics of SiC single crystal had been clarified by nano-indenter, the lapping using green carborundum abrasive grains with grit number #800 and the constant pressure grinding using metal-bonded diamond wheel with grit number #200 were experimented, and conclusions were as follows

A number of efforts have been made by researchers in order to understand the nature of the giant dielectric response in CCTO [1-4,6-7].
IBLC model suggests that the desirable results for high dielectric constant and low dielectric loss could be achieved for CCTO with larger grains and highly resistive grain boundaries. [6] Therefore, focusing the research on microstructure and electrical properties of the grain and grain boundary has become an important method in exploring dielectric properties of CCTO.
Sample sintered at T=1050oC consisted few large grains embedded in small grain of CCTO, indicating the beginning of the grain growth process during sintering [12].
Biggest grain size was observed when the samples were sintered at 1100oC.
The values of grain boundary resistivity, ρgb and grain conductivity, σg are tabulated in Table 2.

Such ingots can have an as-cast microstructure with grains 2-4 cm in diameter and 20-40 cm in length.
The measured hardness was lower on grain boundaries (80HB30) and higher on grain body (120HB30).
This is a dependence on routes number of Bc rotating mode as the full numbers of rotation are 4, 8 and 12.
By passes number increase the GS was decreased and dislocation density was increased, respectively.
Kommel: in Ultrafine Grained Materials III, Ed.

In this paper, we discuss about the influence of impurities on the grain growth during HPT and on the grain size reduction mechanism during SPD.
The limited grain growth reported upon annealing is usually attributed to the pinning of grain boundary by impurities.
Indeed, it has been reported that electrodeposited nanocrystalline Ni with a similar grain size of about 10-20 nm exhibits a significant grain growth during HPT [10, 11].
Measured compositions are given in the table (total number of atoms: 1.08 106) The three dimensional reconstruction of the analyzed volume is shown in the Fig.3.
However, it is for sure much larger than conventional grain boundary segregations observed along equilibrium grain boundaries [19].

Electron backscatter diffraction (EBSD) analyses revealed a number of columnar α-Al grains with a mean size of approximately 10 μm.
STEM-high angle annular dark field (HAADF) image (Fig. 4(a)) shows a number of granular Fe-rich particles with a mean size below 100 nm formed inside the melt pools.
A number column grains with a mean size of about 10 μm appear twisted and elongated along the building direction in the LPBF-fabricated sample (Fig. 5(a)).
The fine substructure composed of high density low-angle boundaries was found inside the α-Al grains.
A number of columnar grains with a mean size of approximately 10 μm were found in the α-Al matrix.

We studied suspensions by means of zeta potential and grain-size measurements.
Grain size and zeta potential measurements were conducted by using a Malvern Zetamaster Nano-ZS.
Since each grain-size distribution contained 70 points, the number of datapoints for the grain size was 700 and the total number of datapoints in each dataset was 710.
For each approach, several datasets were built and analysed, depending on the number of considered suspensions.
Fig. 1: Ten subsequent grain size measurements on the same suspension, i.e.