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These magnetic nanocomposites consist of ferromagnetic nanocrystalline grains with the intragrain easy axis of magnetization varying randomly in orientation from grain to grain embedded in an amorphous ferromagnetic matrix [1].
, (1) where N is the number of grains within a stochastic domain and d is the dimensionality of grain packing.
With increasing the annealing temperature, the grain size and the volume fraction of the crystalline Fe(Si) phase increase.
Grain size vs annealing temperature of the investigated Fe73.5CuNb3Si13.5B9 alloy.
Such dependence is observed in Fig. 3 which represents the DH value vs grain size D.

Introduction Ultra-fine-grained and nanocrystalline materials exhibit a much higher strength than their coarsegrained counterpart [1].
This property was observed for various metals and for grain size as large as 300 nm [1].
The curves from the top to the bottom are for relaxations number 1 to 7, except for the anomalous darker curve which corresponds to number 5.
Compared to the first series, the apparent activation volume, * VΩ , increases with the relaxation number.
The material is made of aluminum grains with size of 100 nm containing particles of γ−alumina with size of 15 nm, located at the Al grain-boundaries (Fig. 5).

The former depends on the number of B atoms substitutionally located in the Si-Si structure.
In this work, the decrease of R is certainly the consequence of an increase in carrier concentration due to the rise in the number of active dopants in the film.
The excess boron may be going to the grain boundaries or to the amorphous matrix where it may not yield a carrier.
Together with the results coming from Raman spectra, it may be considered that the film is composed by crystalline silicon grains with different orientation in the size about 8nm, and there are lots of amorphous phase between the grains.
This increase leads to a redistribution of states, from band to tail, thus allowing for a greater number of possible band to tail and tail to tail transition.

As a result, even magnesium alloys with fine grains have high elongation of more than 30%.
due to fine grain size of about 500nm.
fine-grained through repetitive ECAE processing.
Tensile strength Tensile strength / MPa/ MPa Elongation, ε (%) Elongation Elongation 400MPa400MPa 0 100 200 300 400 500 1 50 100 200 0 5 10 15 20 25 Die-cast Tensile strength Tensile strength 16%16% Number of repeated cycle Number of repeated cycle Tensile strength Tensile strength / MPa/ MPa Elongation, ε (%) Elongation Elongation 400MPa400MPa 0 100 200 300 400 500 1 50 100 200 0 5 10 15 20 25 Die-cast Tensile strength Tensile strength 16%16% Number of repeated cycle Number of repeated cycle Fig.10 Tensile properties of severely-worked Mg-1%Zn-7%Al-1%Ca-3%La alloy.
Realization of High Ductility and High Strength through Grain Refinement etc.

A porous microstructure, giving a path for oxygen to be absorbed on the grain boundaries, is essential to enhance PTCR effect.
A number of routes are employed in order to fabricate porous ceramics for PTCR[7,8].
Heywang [9] proposed the grain-boundary model to describe a resistance abnomalbehavior of doped BaTiO3.
According to his model, the grain boundary potential barrier height can be enhanced withsegregated acceptor ions or adsorbed oxygen at the grain boundaries.
Thus, sintering atmosphere is very important and reducing atmosphere can strongly reduce PTCR effect due to the decrease of oxygen concentration at the grain boundary.

So that big fine recrystallized grains were achieved at the soft primary austenite region while small recrystallized grains were achieved at the hard solidified liquid region.
The initial grain size of the 9Cr18 semi-solid billet was about 93.5μm which was later decreased to 30-50μm by thixoforming.
And the shape factor of these grains was 0.69[7].
Similarly, solidified liquid metal is replaced by clusters of small equiaxed recrystallized grains after deformation.
So far, a large number of deformation resistance models have been studied by researchers to describe the stress change in special deformation conditions.

In [7] a number of activities of metals to oxygen in process of decrease of deoxidizing ability are presented: Al→Zr→B → Ti→Si→V→Mn→Cr→Mo→W→Fe→Co→Ni→Cu
For this purpose respectively, aluminum shaving with a size of grain of 0.2–0.4 mm and graphite with fraction of 0.4–0.5 mm, FeMn, FeSi – with a size of grain of 0.35–0.6 mm were used.
The greatest number of tungsten in an alloy No. 3.1 was received with flux use, as a reducer in which aluminum shaving was applied.
Apparently from fig. 3.a, grain 4 represents a mechanical mix of light and dark phases.
A number of ceramic gumboils on the basis of the scheelite concentrate is developed and approved, allowing at electroslag remelting low-carbonaceous began to receive high-tungsten.

Besides, appropriate amount of nanoparticles in the electrolyte also could offer grain refinement by providing nanocrystalline sized between 30~60 nm with current density in the range of 100~500 A/dm2.
The optimized electrodeposition process parameters were as follows: DC current density 100-500A/dm2, rectangular nozzle (20mm×1mm), electrolyte jet flow velocity (2-10m/s), scan rate 10 mm/s, scanning layer number 200.
This act could be beneficial for the generation of new crystal nucleus as well as preventing further growth of the grown grains.
It also helps the copper grains to be more uniformly dispersed in composite deposits.
It was observed that current density in the range of 100~500 A/dm2 could offer grain refining effect by providing nanocrystalline copper composited coating with size between 30~60 nm.

The average grain size calculate by linear intercept method.
The increase of grain size may be due to the mass transport mechanism in samples during the sintering process, which high sintering temperature free-energy change that gives rise to grain growth is the decrease in the surface area between the fine-grained material and the larger-grain-sized product.
Behavior between dielectric constant and grain size can be explained by G Arlt's theory following formula: Gαd1/2(in the range of grain size of 1-10 µm) [12-13].
It confirmed that a large number of domain walls would lead to enhancement of dielectric constant.
The average grain size increased as high sintering temperature.

Last but not least, there are natural criteria like the availability and there are environmental criteria like low-activation which rule out a significant number of possible alloying elements for tungsten.
Therefore, the main focus of the investigations was laid on microstructure characteristics like grain size, grain shape, and texture.
In rods, the grains are extremely elongated along the axis (needle-shaped).
The images were produced by electron back scatter diffractometry (the crystal orientations are given normal to the surfaces with a reduced number of colours).
The addition of lanthanum-oxide – which forms needles or flakes between the tungsten grains (see Fig. 9a) – obviously weakens the grain boundaries.