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Table 1 Characteristics of the adopted raw materials Starting materials Purity Crystal form Average particle size/Grain colony Si3N4 ＞99% α (13%), β(86％) 3.30μm Al2O3 ＞99% α(49%)θ(25％)σ(25％) 10-80nm Table 2 Formulation of specimens (wt %) Specimen No.
This work indicates that nano alumina can promote the sintering of silicon nitride ceramics from three aspects : (1) It can generate a large number liquid phase distributed homogenously in the matrix because of sinter-active of nano alumina, which avoid the abnormal growth and make the size of plate-like β-Si3N4 more firmly,so the structure of ceramics become more unified[7].(2) The fracture toughness of silicon nitride (Si3N4) materials is commonly related to the development of large elongated grains in their microstructure.
In this study, alumina in nitrogen atmosphere react with silicon nitride to nitride, such as hexagonal Sialon, sheet Si2N2O [8].These silicon nitride form interwoven structure distributed in the ceramics, which enhances the bonder [9]. (3) Using nano alumina can purify the grain boundary and decrease the appearing of low melting point phase [6].But content of nano alumina additions should be in 9-12%.

During the plastic deformation of HCP metals, it is known that twinned and untwinned regions simultaneously exist in a crystal grain.
(2) Here, and are the slip or twinning plane normal and slip or twinning direction vectors, respectively, is the shear strain rate, and is the number of slip and twinning systems.
When we consider a finite element model of a polycrytstal, where a crystal grain is constructed of one or only few elements, a material point in the model should be assumed to include both untwinned and twinned regions.
For comparison, the conventional twinning model, in which the volume fraction of twinning is not considered and deformation twinning occurs whole domain of a crystal grain at same time, is also used.

Table 1 The composite of PcBN (wt%) Raw materials cBN feldspar Si3N4 Si AlN Content (wt%) 70 20 5 2 3 Table 2 Particle size of cBN(wt%) Particle size (µm) 0~0.5 0.5~1 1~3 3~6 6~12 Content (wt%) 30 10 20 18 22 Experimental Procedure High purity cubic boron nitride (M850, grain size 22~36µm, purity>99.5%, Henan Funik Ultrahard Material Co., Ltd. , China), Feldspar powder (analytical pure), Si3N4 (grain size:1µm) and Si were used as the starting materials.
It is because that the grain sizes of cBN ranges from 0 to 12 µm, contain nano-scale cBN particles, which have high surface activity, and hence it is easily occurred crystal transformation and being oxidized even at a low temperature.
found in the sample and when the temperature is 1100°C, the number of pores reaches most.

It is the diamond grain that plays the role of grinding function.
A large number of diamond grits are consumed for the high hardness of granite, which is the main reason for the high processing costs in machining granite products.
The studies about wear of diamond tools were focused on the wear process and forms of diamond grits, some researchers have established the single-particle grinding model of diamond [1], the states of the diamond grain are divided into emergent, integral, smoothed, micro-fractured, macro-fractured and pull-out [2].
Shinsaku Hagiwara et al studied the laws about fracture, shedding and generation process of diamond grain in circular saw by markov process theory [5].

In experiment, the size and purity of SnO2 powder were controlled by adjusting T and S, because T and S affected the speed of forming nuclear and grain growth: S increases so as to enlarge the number of nuclear, to cause reaction processing completely and reduce the size of r*; higher T accelerates the speed of reaction and reduces the size of r*, also enhances the purity of product and enlarges S, but it also accelerates the speed of grain growth so that the size of SnO2 particles becomes larger.
It also reduces the reaction temperature in local area and enlarges extra-saturation (S), which reduces the speed of forming nuclear and grain growth so as to decrease the size of powder.

The crystalline grains are isometric crystals.
There are a large number of twin crystals in the crystalline grains.
The carbide mainly distributes inside the crystalline grains.

Hence the traditional Hough transform is modified as the following Collapsed Hough Transform procedure: (1) Discretise the orientation space into finite number of orientations
Figure 8: Images for reorientation study (images from left to right corresponds to cycle Figure 9: Orientation distribution Figure 10: Local orientation distribution Application of Collapsed Hough Transform to a 3D Volume Recently the 3D grain volume of a hydrided zirconium sample has been reconstructed using an arithmetic reconstruction algorithm [11].
However, the hydride normal in the local crystal coordinate of the neighbouring grains is shown in a pole figure in Fig. 12, which shows that the hydride plate normals are clustered in the {0002} pole direction.
Preuss, Wofgang Ludwig, Grain Mapping by Diffraction Contrast Tomography, International Symposium on Materials Science: Challenges in Materials Science and Possibilities in 3D and 4D Characterization Techniques, Risø, 2010.

Results c) The microstructure consists of α-Mg-grains and eutectic phase consisting of α-Mg and Mg2Ca formed along the grain boundaries; some were located within the grains and some were of globular shape (Fig. 1a).
a) b) polymer coating PCO coating Fig. 1: Appearance of coating systems on MgCa1.0: a) uncoated b) PCO coated c) PCO and polymer coated It can be seen that there are a number of visible pores in the coating.

It was discovered that the emergence of very fine grain area was caused by the expansion of micro cracks along the grain boundary in the adiabatic shear cracks of Ti-6Al-4V alloy[11].
Experimental The material used in this study was annealed commercially pure titanium with equiaxed grains. 
The number of initial lamellar dislocation boundary structures decreases sharply.

Both films have polycrystalline structure but grain boundary is well developed in the film of 30 W.
These surface and grain boundary structure will be connected to TMR and RJ of MTJ devices.
High barrier height at 60 W could be acquired by fast oxidation through the well developed grain boundary.
Journal Title and Volume Number (to be inserted by the publisher) can say that 10 minute oxidation at oxygen gas environment is enough for the pseudo-crystalline surface but not enough for the amorphous like surface to fabricate tunnel barrier.