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Recent efforts to develop creep-resistant magnesium alloys have resulted in a number of experimental alloys.
Grain size measurements were performed using the lineal intercept method described in ASTM standard E112 88, and more than 40 intercepts were counted for each grain size determination.
The effects of Ca addition on grain size is shown in Fig.2.
When adding 1.0wt% Ca element, the grain sizes of AZ91D alloy reduces evidently to about 107mm compared with original grain size of about 166mm.
However, Al2Ca phase formed on grain boundary has the f.c.c structure.

In this process, glass grains belonging to CaO-Al2O3-SiO2 family were crystallized depending on surface crystallization mechanism.
The β-wollastonite crystals could primarily deposit at the surfaces of glass grains and subsequently grow toward the interior of them.
Cracked-glass panels and glass grains were parallelly heat-treated through two-step method in an electric furnace with a programmable controller.
Of course, the cracked-glass panels were kept still in the moulds, while glass grains should be filled in new moulds with the size of 60×60×25 mm3.
The 1 000 multiple micrograph (Fig.3a) shows that the CG-GCs are composed of pine-like druses and residual glass phase, while the 10 000 multiple micrograph (Fig.3b) further reveals that the pine-like druses are piled by a number of granular crystals with the size ranging from 0.2µm to 0.5µm.

The rapid solidification exhibits characteristics, such as extension of solid solubility limit, often by orders of magnitude, a reduction in grain size, a reduction in both the number and size of segregated phase and production of new non-equilibrium alloy phases, though these advantages of course do not, all occur simultaneously.
The grain size of α-Fe2Si5 phase with polygonal shape is 300-500 nm, whereas the grain size of ε-FeSi phase is 50-150 nm.
Despite the different size distribution, the average grain size for β-FeSi2 phase is about 500 nm in alloy.
The fine grain size of melt-spun and sintered specimen increased the scattering factor.
The grain size of α-Fe2Si5 phase and ε-FeSi phase has a range of 300-500 nm and 50-150 nm, respectively.

The calculated grain size is about 84 nm.
Such ion replacement increases number of electrons in the doped films.
The conductivity of the film increases due to increasing the number of charge carriers.
The electrical resistivity of the films depends on grain size.
It increases with increase in grain size.

Granular precipitated phase inside grain is reduced, and precipitated phase is mainly distributed along grain boundary, which makes grain boundary become broad, as is shown in Figure c).
Precipitated phase at grain boundary of alloy 5 increased further and is distributed along grain boundary in the shape of network.
In addition,α-Mg crystallizes firstly because α-Mg needs smaller super-cooling degree, Zn and Y have lower solid solubility on the α-Mg substrate,a large number of zinc and Y elements were stranded in the liquid phase, at last Y and Zn are promoted toward grain boundary in the form of precipitated phase [12].
It only promotes formulation of grain to inhibit the growth of grain as crystal nucleation particle during the process of alloy solidification.
From XRD result of alloy, we can see main precipitated phase of alloy 2 is quasi-crystal phase I, distributed along grain boundary or inside the grain.

MgFe2O4 nanoparticles with different grain sizes were prepared by the low-temperature solid-state reaction method.
Fig. 2 shows the hysteresis loops of MgFe2O4 nanoparticles with different grain sizes.
In addition, it is seen that the magnetization (M) at 954.9 kA/m (12 kOe) applied field increases with increasing annealing temperature, which can be attributed to the following: firstly, the grain size of our samples is much smaller than that of bulk materials, which induces an increase in the number of grain boundaries, the large surface and interface supplying more pinning sites for domain walls [3,5]; secondly, following the increase of the annealing temperature, the grain size of the films increases and the microstructure become well-crystallized.
Hysteresis loops at RT for MgFe2O4 with different grain sizes nanoparticles.
XRD patterns of MgFe2O4 ferrite nanoparticles with different grain sizes .

Extensive work has been done by a number of researchers in order to reduce temperature of the transformation to α-phase.
�Grain growth was also accelerated at above 1300 o C and the average size of grain at temperature of 1400 o C was 482 nm as shown in Fig. 2.
All the α-Al2O3 specimen showed densification behavior without any noticeable grain growth. 0 20 40 60 80 100 0 250 500 750 1000 1250 1500 70 75 80 85 90 95 100 Relative density (%) Average grain size (nm) Volume fraction of αααα-Al2O3 (%) Density Grain size Fig. 2.
Changes of grain size and relative density with temperature. 1000 1100 1200 1300 1400 200 250 300 350 400 450 500 αααα/(αααα+γγγγ) fraction=90% Average grain size (µµµµm) Sintering temperature ( o C)Fig. 5.
Therefore, the fine grained microstructure of the 90% αAl2O3 specimen was caused by the inhibition of grain growth owing to the zirconia particles which were contaminated by high speed attrition milling.

The number of abrasive dust decreases and the furrows get wider with slight tearing under 294N.
A large number of different abrasive dusts cover the surface which mixes with the coating.
Under low load, normal stress and shear stress are very small, so only a small quantity of hard grains are peeled and result in slight abrasive grain abrasion.
Abrasion mechanism of laser coating remains abrasive grain abrasion.
With the load increasing, abrasive grain abrasion intensifies

The complex of computer programs was used by treatment of measured X-ray data, including large number of experimental results.
According to the X-ray diffraction theory [5], each profile characterizes a condition of the crystalline lattice in reflecting grains along axes .
Additional scattering of texture maxima in Fig. 2-a, as compared with that in Fig. 1-a, indicates that the attainment of texture maxima by grains at the outward side of tube happens more difficult, than by grains at its inward side.
More extensive regions of scattering in GPF β002 (Fig. 2-b) confirm the higher strengthening of most grains at the outward side of tube.
(2) The most effective criterion for systematization of substructure inhomogeneity in textured metal materials is crystallographic orientation of grains

Introduction ZnO varistors are well-known electronic ceramic devices produced by sintering the mixture of ZnO and a number of other metal oxides, such as Bi2O3, Pr6O11, La2O3, Co3O4, Sb2O3, MnO2, Cr2O3, etc.
The samples doped with alkali ions contain smaller ZnO grains than the undoped samples, indicating that the doping of alkali ions could inhibit the growth of ZnO grains.
The varistor voltage of ZnO-Pr6O11-based ceramic varistors correlates to the size of ZnO grains and the applied voltage per grain boundary, Vgb.
The varistor voltages of the varistors are proportional to the number of grain boundaries between the two applied electrodes, which is in inverse proportion with the ZnO grain sizes.
Bradt, Grain growth of sintered ZnO with alkali oxide additions, J.