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We propose that these sintering aids may create a glass-like shell that envelops the ferrite grains, impeding the conductivity in the grain boundary regions.
Raman spectra of the obtained samples, a) spectra of grains, containing mostly hexaferrites phase, b) spectra of grains with hematite phase.
The microstructure of the sample without sintering aids consists of hexagon-shaped plate-like particles and also particles of complex form with a large number of faces with an average size of 1.28 µm.
Although the average grain size for both samples was 1.86, very large grains ~10 µm were present in the Bi2O3 sample in parallel to small grains ~ 1.5 µm, while the grain size distribution in the V2O5 sample was smoother.
Notably, in the samples containing B2O3 and V2O5, α-Fe2O3 hematite grains were observed along with SrAlFe11O19 hexaferrite grains.

Cavities defined a deficit of mass by separation or uncoupling of grains or blocks of grains in SPASM.
In general the technique to measure cavitation with scanning electron microscope microphotography at mesoscopic level and quantitative metallographic on SPASM after deformation provides the essential information to construct the histograms of the number of cavities as a function of the cavity area.
Such analyses have revealed that the cavities volume generated during SPF in SPASM are due to sliding of grains or block of grains [7].
In this context, it has been established that the cavities volume generated during super plastic flow in SPASM are due to sliding of grains or block of grains associated with the nature of cellular dislocations [.
Grain growth takes place during exposure at temperatures above 1723K, and this grain growth is enhanced by external stresses such as those found in SPF, resulting in dynamic grain growth [15]. 0 10 20 30 40 50 60 70 0 5 10 15 20 25 dc/dg Relative Frequency of Cavities f(dc)% Material: 3Y-TZP Temperature: T = 1723K Grain size: dg = 0.5 µm Strain Rate: ξ= 2.8x 10-4 s-1 Fig. 5.

The grain clusters have a wide size distribution from 200 nm to 2000 nm.
According to Maxwell - Wagner model [30, 32], the polycrystalline dielectric materials are imagined with a two layer structure: the first one being a heterogeneous medium of conducting layer consisting of large number of grains and the other one is highly resistive grain boundaries.
A dielectric material is assumed to be made of conducting grains that are separated by non- conducting grain boundaries.
Therefore, the grains are more conductive as compared to the non-conducting grain boundaries.
When electrons reach such non-conducting grain boundaries, they pile up at the grain boundaries due to the high resistance and produce polarization.

The results were coincide with the change rule reported by other literature, in which the number of microorganisms decreased as the extension of storage time under conventional storage[11].
Journal of Grain and Oil Processing and Food Machinery.
Journal of Grain in Heilongjiang Province Vol.1(2002),p.39-40
Journal of grain circulation technology.
Grain oil and food microbiology.Beijing: China light industry Publishing company 2002. p.302

Chipping is the brittle destruction of grains with the separation of large particles that are commensurate with the size of the grains.
The surface is formed by longitudinal scratches left by the tops of the grinding wheel grains.
Adhesive interaction on the trajectory of the top of the grain is minimal.
Morphology of the treated surface of object 3 (a), relative intensity of x-ray characteristic radiation (b), and concentration of chemical elements in Spot 3 (c) Acknowledgments The reported study was funded by RFBR, project number 19-38-90322\19.
Jiuhua, Effect of grain wear on material removal behaviour during grinding of Ti-6Al-4V titanium alloy with single aggregated cBN grain.

With regard to the evident size effect of strength, a number of theoretical models, such as Hall-Petch model (σy∝λ -1/2), Orowan model (σy∝λ -1ln(λ)), Koehler model (σy≠f(λ)) and so on, have been proposed to interpret experimental findings quite well in different length scale range [7-10].
In-plane surface grain size was observed to increases with increasing λ shown in Fig. 1.
Especially for the λ=25 nm multilayer, the shear band width always keeps in the order of one or two grain size, which is strong evidence of low strain hardening ability of small grains.
However, for the λ=25 nm multilayer, due to the small λ/grain confinement the limited dislocation storage capability may make the gliding stress of the dislocations existing in the deformed grains nearly equal to or smaller than the strength of the undeformed grains, which was controlled by dislocation creation stress.
Thus, the shear stress required for dislocation gliding in the deformed grain is just about 99 MPa, and even lower than the stress of 166 MPa for dislocation creation in the undeformed grain [17].

Ratio was repeatedly carried out in the test, aluminum powder of 200~300 mesh numbers and ferric oxide of 100 mesh numbers were selected.
And grains have been uniform deformed in the crack propagation process, indicating better crack resistance of the welded joints.
Microstructure of welded joint In (a), cellular dendrites distributed in the structure of welded seam, which was formed by crystal nucleation, growth and solidification in molten pool, and the metal crystal nuclei grew on the grain surface of base metal on molten pool.
Therefore in order to achieve thinner rod-like grains in weld metal, the welding process should be controlled in case of grain overheating and coarsening of base metal.
And grains had been uniform deformed in the crack propagation process, which indicated the crack resistance of the welded joint was good.

The average number value of d50 and d90 is 1.86μm and 4.30μm.
We draw the conclusion that: this white slime grain of the sample belongs to superfine.
For the argillization of the white slime in the stirring current, we should weigh the white slime in timing measurement, the average number shown in table 1.
The slimmer the grain is, the smaller the gravity is.
The Brownian motion intensifies, which keeps the grains in suspension, slime water in the stable state, and the process is extremely difficult to deal with[3].

Because there are many grain larger than 4.75mm in the rock chips, when calculating the sand-aggregate ratio, classify such grain as coarse aggregate, others as sand.
Because the grain larger than 4.75mm is 16.1% in the rock chips, the quality of rock chips is m/0.84.
One reason of this phenomenon is that the rock chips is a coarser surface, multi-angular and high surface area material, so the fine aggregate grain in the mixture create more mechanical locker, and the internal friction between the grains is relative large.
In addition, a large number of rock powders can play as the slurry, which can cover the grain surface, reduce the internal friction, and improve the flowability of mixture.
(4) In the high strength concrete, the suitable rock chips is a aggregate with less grains larger than 4.75mm and better grain size distribution.

In the embrittlement zone, the specimens were fractured with little plastic deformation by either grain boundary sliding or by localization of strain in the film proeutectoid ferrite produced by the γ→α transformation.
Narula investigated the effect of grain size on polarisation behaviour of weather resistant steels [7].
The presence of the softer film of ferrite surrounding the stronger austenite grains in 750-950oC would cause the strength to level off so that there is little change in strength in this temperature range.
The relationship of hot ductility and fracture strain with temperature Practical experience and a large number of studies show that [10, 11]: when the %R of A value is above 60%, steels do not crack; when the %R of A value lies between 40% to 60%, there is a low incidence of cracks; however when the %R of A value is lower than 40%, steels display a higher crack sensitivity.
The surface morphology is well coincident with the high ductility, which manifests that there is a considerable volume fraction of proeutectoid ferrite surrounding the austenite grain boundaries after occurring γ→α transformation reported in other literatures [12, 13].