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Therefore, it is better to take the machining gap for 2.2mm. 4.6 Influence of grain size on surface roughness Fig.12 presents the relationship between the grain size and surface roughness.
The grain size of the honing stones attached in abrasive cathode tools directly affect the strength of the mechanical finishing, Fig.12 indicate: with the number of mesh increasing, the diameter of abrasive particles becomes smaller, and the scratches caused by the particle on the workpiece are shallow, so the surface roughness value is small, when using this two kinds of cathode tools to processing, the grain size of the honing stones should not be less than 300 mesh.
By analyzed the experimental results, simulated a set of reasonable process parameters is simulated: in the process pf rough finishing, machining voltage 20V, pulse duration 200µs, rotation speed 147 r/min, finishing pressure 0.7kgf, machining gap 2.2mm and grain size 360mesh; in the process of fine finishing, machining voltage 25V, pulse duration 100µs, rotation speed 147 r/min, polishing pressure 0.7kgf, machining gap 2.2mm, and grain size 300 mesh.

The size of the main-phase grains is about 15μm, and the size of the minor-phase grains interspersed along the grain boundaries (and surface) of the former is less than 1μm.
The minorphase grains grouped together like grapes.
The micro-domain analysis shows the bigger grains with components in the ratio of Sr: Co: Fe: Sn=1: 0.82: 0.1: 0.09 (Area 1 in Fig.3), and smaller grains with components in the ratio of Sr: Sn: Co=0.93: 0.88: 0.12 (Area 2 in Fig.3).
[12] JPCD cards, file number: 82-2445

Nahar et al. found that the as-deposited sputtered high-k films are usually loosely packed and contain large number of impurities and defects such as oxygen vacancies, oxygen interstitials, and/or oxygen deficiency, resulting in increased oxide charge and leakage current.
As can be seen, the crystal size of pentacene on non-annealed DNA-OTMA was higher than that of post-annealed one, with increase in post-annealing temperature, the grain size of pentacene decreased.
As shown in the figure, the distance between the grains became larger with increase in the temperature.
From Figure 3, the larger grain size sample gives the higher ON current.
It can be explained that the small grain size tends to have voids, therefore, the larger grain boundary would be formed, so the carrier scattering increased and the carrier transport was degraded during carrier transport process.

A large number of efforts have been made in the field of quench sensitivity and its mechanism.
When 7B04 Al alloy slowly cooled from an elevated temperature, alloying elements are precipitated and diffused from the solid solution to concentrate at both grain boundaries and undissolved particles, as seen in Figure 3(b),(c).
In contrary, no significant variations in precipitates inside the grains can be observed for the novel alloy when increasing the distance from the 5 to 100 mm from the quenched end, whereas excessively slow cooling allowed excessive concentrations of alloying elements to develop around the grain boundaries, as illustrated in Figure 4(c).
Meanwhile, there are some coarse η precipitates nucleated inevitably on Al3Zr dispersiods inside grains, but only in a few local grain areas, as shown in Figure 5.
(a) 5mm; (b) 40mm; (c) 100mm Fig.5 Quench-induced precipitates inside partial grain of the novel alloy at 100 mm distance from quenched end Based on the quench sensitivity curves measurements and the microstructural observations of the three Al-Zn-Mg-Cu alloys mentioned above, it can be seen that quench sensitivity of 7xxx series Al alloys is determined by main alloying elements (Cu, Zn and Mg), dispersoids elements(Zr or Cr), and other minor elements(Mn, and Ti).

This process has a number of merits, such as less gas porosity, low shrinkage porosity, no metal wastage, good cast ability, near net shape, and good mechanical properties [6-7].
This technique inserts fine gas bubbles into a molten metal during the initial stage of solidification to produce a slurry of non-dendritic grains.
This technique has many advantages, including improved mechanical properties, spheroidal grains, and less porosity in the cast products [10-12].
After ageing the supersaturated β phase decomposed quickly, and the discontinuous precipitation was developed at the grain boundaries [14].
Grain refinement of an aluminum alloy by introduction gas bubbles during solidification.

The austenite grains are elongated on ferrite matrix, which is related to the production processing [4].
The gradient distribution of grains may be attributed to the gradient distribution of accumulated plastic strain.
It can be seen from Fig. 5(b) and Fig. 5(d) that a large number of micro voids and equiaxial dimples distribute non-uniformly on fracture surface, which belongs to the ductile fracture.
Grain refinement of Cr25Ni5Mo1.5 duplex stainless steel by heat treatment.
A novel severe plastic deformation method for fabricating ultrafine grained pure copper.

Table 1 Process parameters settings of the six sets of single factor experiment Experiment number and the fixed cutting parameters Variable Specific parameter value Single factor experiment No.1 (SFE No.1) (WOC=0.1mm,n=10000rpm, fz=0.13mm/z, tilt=-25°, lead=25°) Depth of cut DOC [mm] 0.1/0.15/0.2/0.25/0.3 Single factor experiment No.2 (SFE No.2) (DOC=0.2mm,n=10000rpm, fz=0.13mm/z, tilt=-25°, lead=25°) Width of cut WOC [mm] 0.05/0.1/0.15/0.2/0.25 Single factor experiment No.3 (SFE No.3) (DOC=0.2mm, WOC 0=1mm fz=0.13mm/z, tilt=-25°,lead=25°) Spindle speed n [r/min] 8000/9000/10000/11000/12000 Single factor experiment No.4 (SFE No.4) (DOC=0.2mm,WOC=0.1mm,n=10000rpm, tilt=-25°, lead=25°) Feed per tooth fz [mm/z] 0.06/0.09/0.12/0.15/0.18 Single factor experiment No.5 (lead=0°) (SFE No.5) (DOC=0.2mm,WOC=0.1mm,n=10000rpm, fz=0.13mm/z, lead=0°) Tilt [°] 5/15/25/35/45 Single factor experiment No.6 (tilt=0°) (SFE No.6) (DOC=0.2mm,WOC=0.1mm,n=10000rpm, fz=0.13mm/z, tilt=0°) Lead [°] 5/15/25
The surface grain directions of the first four pictures are approximately identical, while two different grain directions parrallel to and perpendicular to the feed direction exist in the last two pictures.
The grain directions generated by the multi-axis ball end milling process are closely related with the tool inclination angles.
A certain intersection angle exists between the direction of cutting speed of engaged cutting edges and feed direction for the preceding cutting condition from SFE No.1 to SFE No.4, which directly leads to the grain direction.
The grain direction in parallel with feed direction appears when only tilt angle is adopted, and the grain direction is approximately perpendicular to feed direction when only lead angle exists in cutting process.

Different displacement of artificial bone under different adhesive layer thickness Here, the porosity of HA artificial bone scaffold is composed of porosity of HA small balls accumulation model and internal grain porosity of each HA microsphere.
The internal grain accumulation pattern of a HA microsphere is long cylindrical grain.
is the grain radius of a single HA microsphere, and ε is the internal porosity.
Section of hydroxyaptite long cylindrical grain for a single HA microsphere [4] (1) The volume of solid bone scaffold: (2) considers the volume of the internal pore: (3) represents the unit volume of HA solid material in bone scaffold, is the total pore volume of HA bone scaffold cell within the artificial bone scaffold
(4) rs represents the radius of HA grain.

In the 1980s and 1990s, a number of studies involving a wide variety of powder systems were carried out and this established MA as a robust powder processing route (4) .
Nanocrystalline materials generally have grain sizes lower than 200 nm(5) and the improved physical and mechanical properties of the materials are due to the nanometer scale grain size as well as high volume fraction of grain and interface boundaries (5 - 7) .
The particle size, morphology, grain size and phase constituents of the milled powders from the different batches were determined and compared with the "as received" powder.
The use of this equation is based on the physical origin of broadening of the XRD reflections by the small grain size only.
The grain size thus obtained is volume averaged in the direction perpendicular to the diffraction plane.

The particle is W7 Al2O3 with primary mean grain size of 6.3µm.
The SEM images of grinding surface and abrasive jet finishing surface machined with 10% grain weight concentration slurry are shown in Fig.2.
Further, as the number of cycles increases, the Ra value decreases.
With the number of cycles increase the Ra value decrease for the three abrasive concentrations.
With higher abrasive concentrations, more abrasive grains come into contact with the workpiece resulting in more abrasion, hence higher Ra value.