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High-Pressure Influence on the Kinetics of Grain Boundary Segregation in the Cu-Bi System L.
The effect of pressure on the kinetics of grain boundary (GB) segregation in the Cu-50 at.
After further simplification one obtains ( )20 0 4ln 2 rDtr Dx J b= . (7) Total number of atoms diffusing into dislocations in the vicinity of a GB in a certain time t is then ( )∫ ∫ == t bd t d rDt dt' DxπLnJdt'LnπrN 0 2 0 0 0 4ln 2 ∆ , (8) where L is the dislocation length and nd is the dislocation number.
The specimens were investigated by means of Auger electron spectroscopy (AES) to determine the Bi amount at grain boundaries.
Grain boundary enrichment in dependence of pressure for Cu-50 at.ppm Bi.

Fig. 1 Elastic modulus, C11 - C12, and ideal shear strength, tmax, vs. valence electron number per atom, e/a, in bcc Ti-Nb binary alloys.
Fig. 2 Experimental elastic modulus, C11 - C12, by literature [11] and ideal shear strength, tmax, vs. valence electron number per atom, e/a, in Fe-Ni binary alloys.
The averaged grain size after HPT is 20 - 50 nm as previously reported [3].
How the elastic anisotropy affect the process of grain refinement during HPT?
Such localized transgranular shear seems to contribute to the significant grain refinement in the present case, and the inhomogeneous distribution of grain size shown in Fig. 4 would be attributed to this grain refinement process.

Phase transition grain refinement is the one of main ways that refined grains, importantly, which is used to refine grains that is deformed in the phase transition γ→α.
Good casting microstructure, refined recrystallization austenite grain and the deformated unrecrystallization austenite grain lay the foundation for the final ferritic grain refinement.
In Figure. 2, deformated austenite grain is composed of two parts, one part is the recrystallizated grain, the other part is unrecrystallizated grain.
Not all the deformated austenitic grain has the same capacity of nucleation, so some ferrite from recrystallizated austenite grain is non-uniformity, the non-uniformity leads to duplex grain microstructure.
(2) The microstructure from continuous cooling transformation is a large number of ferrite and some pearlite, when the cooling rate is higher than 30˚C/s, a small number of granular bainite is in the microstructure.

The average grain size was controlled to 28 and 238 µm in order to understand the effect of grain size on mechanical property and flow behavior.
At room temperature and 943 K, 0.2% offset yield strength increased with decreasing grain size to exhibit grain size dependence.
At 943 K, a specimen with the average grain size of 28 µm showed higher yield strength than that obtained with a specimen having the average grain size of 238 µm.
Concerning the yield strength, the alloy with 28 µm is Journal Title and Volume Number (to be inserted by the publisher) 3 observed to have higher strength than that of 238 µm.
Journal Title and Volume Number (to be inserted by the publisher) 5 [2] M.

Here, GBs denote interfaces between UNCD grains and those between UNCD grains and the a-C matrix.
Since the disappearance of diamond grains brings about the disappearance of a huge number of GBs, the sudden decrease in the electrical conductivity should be attributed to the disappearance of GBs.
From the XRD measurement, it was found that the sudden decrease in the electrical conductivity exactly coincides with the disappearance of diamond grains in the films, and therefore, with the disappearance of a huge number of GBs.
From the XRD measurement, it was found that the sudden decrease in the electrical conductivity just coincides with the disappearance of diamond grains in the films, in other words, with the extinction of a huge number of grain boundaries.
A huge number of GBs that is the distinctive structure of UNCD/a-C:H films should play a significant role in the nitrogen doping specific to UNCD/a-C:H.

Image-pro Plus and Adobe Photoshop CS software were used for statistical analyses of the number and size of carbides.
Fig.2 Average number and size of different kinds of carbides in specimens tempered at 400oC.
(a) (b) are for the carbides precipitated at original austenite boundary; (c) (d) are for the carbides precipitated in grain interior Fig.2 shows the number and size of carbides intempered specimens with different magnetic field strength.
This indicates that the magnetic field hinders M2C carbide precipitation.As Fig. 2 (c) (d) shows, for M6C and MC carbides precipitated in grain interior, when applying a magnetic field, their precipitation number increases and the average size decreases obviously.
No M2C carbides precipitated in grain interior for tempered specimens.

Crystalline grain level could be a transition zone between macro and micro level material.
The reasons for enhancement of carrying capacity are: the grain boundaries become irregular or grain boundaries become more twists and turns.
The elements in affine transformation matrix [S] can be determined by the complexity of the grain boundaries which means the number and the twist of grain boundary interfaces
[ε0] is initial strain vector, which is caused by tension or compression of the grains.
After strengthening, grain boundary of the material is pulled pressure and distorted.

Scandium (Sc) has the ability to refine grain size of cast aluminium structure.
In addition of Sc refined grains of aluminium alloy.
For Sc content increased gradually from 0.03 to 0.70 wt.% as a result grain boundary segregation has eliminated to refine cast grain of alloys.
It also depends on number, size and density of precipitates at the moment maximum value is reached.
Addition of0.08 wt.% Sc or more leads to marked grain refinement in aluminium alloys, accompanied by a change from dendritic grain structure to an equiaxed grain morphology. 2.

Acicular ferrite has high misorientation angle boundaries and a number of sub-boundaries or high density of dislocations inside, which contributes to an excellent combination of high strength and toughness.
While granular bainite has a large grain size (approximately 40μm in width).
In terms of EBSD analyses data the average grain sizes of these specimens were 3.9, 4.4 and 2.9μm respectively, and the fractions of their low-angle grain boundaries were 14.1%, 21.4% and 21.4% respectively.
The other line (CD) with misorientation varied frequently between 0.5 and 2 degree within an acicular ferrite grain presented that the acicular ferrite contains a number of sub-boundaries, which can be also supported by Fig. 4.
Fig. 5 misorientation characteristics of acicular ferrite (a) orientation map, (b) misorientation between acicular ferrite grains and (c) misorientation inside acicular ferrite grain Conclusions Acicular ferrite formed within deformed austensite grains can be obtained in the hot rolled low welding crack susceptibility steel.

It is also presumed that hydrogen atoms inside grains are transported with the aid of mobile dislocations to the grain boundary depending on strain rate [3].
The average grain size after the heat treatment was 16.3 µm.
In the condition for the QMS2, the signals corresponding to the mass numbers from 1 to 4 were all detected.
It is obvious that the mass number 3 and 4, which represent HD+ and D2+, respectively, were detected only from D-charged specimen in the stage of deformation.
When we estimate the hydrogen concentration at grain boundary assuming that the first evolution peak represent hydrogen atoms segregated at grain boundary, the value becomes about 3.0×10-7 mol / m2.