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Black precipitated particles scattered both in grain and at grain boundary.
However, the grains in HAZ change darker and their boundary get brighter than those in BM.
The number of precipitated particles in HAZ is less than that in BM, indicating that part precipitated particles in HAZ has dissolved in Al matrix during FSP.
The grains in SZ are fine equiaxed grains due to dynamic recrystallization and depressing function of AlN particles to grain growth during FSP.
Furthermore, there are no AlN particles in TMAZ to prevent grains from growing.

The first stage of wear as the initial wear stage is broken and the overall fall off of the abrasive grains, the reason of which is the abrasive grains on the working surface of the tool after trimming is affected by the impact of the dressing tool and cracks.
Under the effect of cutting force, a chunk of fragmentation happen to the abrasive grains with cracks and the loose abrasive grains will overall fall off which is shown by the rising curve steeper.
The grain size of the PCD diamond tool is 140#, the line speed of the tool: 30m/s,rotational speed of the work-piece: 0.5m/s.
Impact of the work-piece speed on cutting ratio The grain size of the PCD diamond tool is 140#, the line speed of the tool: 30m/s, radial depth of cutting: ap=0.008mm.
(6) c-the number of effective abrasive of the tool in unit area, α-the half-width of the undeformed chip cross section, ap-he depth of cutting, ds-diameter of tool.

One is adding foreign nucleating agents taking Zr [9] for example to increase the number of nuclei.
Therefore, grain growth is confined [11,14,15].
Potential nuclei will be activated in the constitutionally supercooled zone, and increasing the number of nuclei.
With the addition of Zn, the solubility of Y in the Mg matrix is decreased and the volume fraction of Mg24(YZn)5 is increased, which results in the increment of nuclei number and grain growth restriction.
Consequently, the grain size is decreased by Zn addition.

Several passes of ECAP were effected to attain different strain values εn (n is the number of passes).
If in the alloy's initial condition cementite plates in pearlite grains were relatively rectilinear (Fig. 5a), then after 8 passes of ECAP at 250 °C in pearlite grains there are observed heavily distorted cementite plates (Fig. 5b).
This vividly indicates the development of rotational deformation mechanisms in pearlite grains during ECAP processing.
At the same time, the increase in the density of dislocations and other defects in the grain interior and at grain boundaries and the presence of useful impurities in interfaces, correspondingly, contribute to further structure refinement in the alloy [14-16] and, consequently, to an increase in yield strength and microhardness.
Langdon, Structural Evolution and the Hall-Petch Relationship in an Al-Mg-Li-Zr Alloy with Ultra-Fine Grain Size,- Acta Mater. 45 (11) (1997) 4751-4757

Mostly parallel extrusions run in one large grain up to the grain boundary.
Fig. 1b SEM image of the grain with tilted 45 degrees; 300 + 300 cycles, εap =1x10 -3.
Vacancies were produced and positioned in lattice points within the PSB using random number generator.
Number of jumps n characterizes the vacancy mobility and increases with increasing temperature.
With increasing number of vacancies formed within a PSB an extrusion and two intrusions arise and grow.

Linear regression of the data from thermal simulation and grain growth experiments, obtained Dynamic recrystallization and grain growth of the mathematical model of P91[4,5,6,7].
In addition, the dynamic recrystallization and grain growth models also were required to be imported, they are shown as follows: Dynamic recrystallization model Grain growth model: Table 2 Initial parameters setting of numerical simulation Billet material Mold material Billet temperature Mold temperature P91(10Cr9Mo1VNb) H-13 1100°C 250°C number of blank grid Extrusion speed Friction factor Step time increment 100000 26mm/s 0.04 0.01s Analysis of the average grain size (a)Extrusion ratio is 5 (b)Extrusion ratio is 7 (c)Extrusion ratio is 9 Fig. 2.
When the extrusion ratio is 5, The radial average grain size of steel pipe is 40.8μm; Axial average grain size is 32.45μm;when extrusion ratio increases to 7, radial and axial grains are gradually refined, grain size in each direction respectively is 28.71μm, 25.6μm; when the extrusion ratio increases to 9, radial and axial grain size in average is the smallest, respectively is 22.56μm, 24.1μm.
Therefore, the increase of extrusion ratio is good to grain refinement.
Average grain size of P91 steel pipe under different extrusion ratio of numerical simulation The analysis of dynamically recrystallized grain size The dynamically recrystallized grain size of the pipes whose extrusion ratio is 5,7,9 can get that the dynamic recrystallization grain size when the extrusion ratio is 9 is less than the size when the extrusion ratio is 7.

Other leading the body number 1, tending to the shale assise, which is controlled by the cross-section of relative to lamination of the crushing and crumpling zone, which has the north-western direction.
Arsenopyrite is crystalline grained, shape of the grains is rhomboid.
In pyrite III, arsenopyrite grains are found.
The form of pyrite grains is cubic.
The gold (Au) in the grain of pyrite III (Py) with inclusions of grains arsenopyrite.

In the structure of a specimen cut-off along the rod axis, are visible elongated grains of the a solid solution as well as numerous precipitations of the intermetallic phase: CuAl2, Al3Mg2, Al6Mn, which contain iron Cu2FeAl arranged in a streaked way, found mainly on the grain boundaries (Fig. 1).
Fig. 4 Exemplary fragments of the energy parameter history, W(t) under bending in time, t = nDt, n – number of discreet values of the history, Dt = 1.2987×10-5 s – sampling time Cracks of specimens from aluminium with a phase structure occur in the slip plane {111} under shear stress, which are almost independent of grains space orientation.
In the specimen (Fig. 5) it is observed the main, zigzag crack developed through transcrystallic a phase grains.
This crack is changing direction on grain boundaries.
This work was partly supported by the National Centre for Research and Development, Contract Number: N R03 0065 06/2009 and the European Social Fund.

The change of average grain size with various Nd content is exemplified in Fig. 4(b).
Addition of Nd with more than 1.5wt.% leads to consumption of a greater number of Al atoms in Al-Nd precipitates which diminishes the grain refining effect of Al in Mg-9Li-3Al alloy.
Al is also one of the most favorable elements for grain refinement and solid solution strengthening in Mg-Li alloys; formation of Al2Nd, Al11Nd3 consumes the greater number of Al atoms during the solidification it leads a reduction in grain refining effect and solid solution strengthening the effect of Al.
Nd having a strong grain refining effect on Mg-9Li-3Al alloy.
Average grain size is reduced from 143μm to 103μm and best grain refinement obtained in 1.5wt.% Nd.

Further analysis revealed that the major improvements in microwave sintering were the material microstructure, the grain size was significantly reduced, the magnetic domain short-range order was increased so that the degree of orientation was increased, and although the fusion was existed between grains, the grain boundaries did not disappear.
Take the lattice imperfections as the nucleation point, and with the rise of microwave sintering temperature, the more the number of defects (see Fig. 3) were, the easier the formation of the magnetization reversal nucleus was, thus the lower the coercive force was.
From the photographs, it can be seen that the grain size of samples sintered by MS is smaller than samples by CS.
(3) The grain size of samples sintered by MS was smaller than samples by CS.
In the samples sintered by MS, the crystalline grain would be melted, but the grain boundaries did not disappear.