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There is a large number of dimple tissues at the fracture and evenly distributed.
It can be seen from Figure 4a that the steel plate is mainly composed of a large amount of polygonal ferrite and a small amount of pearlite distributed at the ferrite grain boundary.
The ferrite grain size has good overall uniformity, the grain boundaries are clear, and the pearlite is evenly distributed among the ferrites.
The ferrite grain size is determined to be 10 and the band structure is 1.5.
The fine and uniform grain structure of gold is the main reason for the excellent ductility of steel plates.

TG (1), DTG (2) and DTA (3) curves of Nikitsky clay powder A number of endothermic effects are observed on the DTA curves for the Nikitsky and Staroshaigovsky clays.
At the same time, a number of compositions with thermally activated Nikitsky clay have compressive strength exceeding that of the unmodified composition.
Figovsky, Silica fumes of different types for high-performance fine-grained concrete, Magazine of Civil Engineering 78(2) (2018) 151-160. https://doi.org/10.18720/MCE.78.12 [9] Y.
Volodin, Modified fine-grained concretes based on highly filled self-compacting mixtures, IOP Conference Series: Materials Science and Engineering 481(1) (2019) 012048. https://doi.org/10.1088/1757-899X/481/1/012048 [12] T.A.
Korovkin, Fiber fine-grained concretes with polyfunctional modifying additives, Magazine of Civil Engineering 72(4) (2017) 73-83. https://doi.org/10.18720/MCE.72.9 [13] R.Z.

Besides, nano-grains in the coating seriously bridged [16].
There was not enough time for the nanoscale pores between the grains to diffuse outward.
After erosion once, since the coating of the number 1# (see Fig. 3 (b)) did not protect by the dense layer, it was eroded most obviously.
While the number 4# composite coating maintains yellow, indicating that the dense layer did not break obviously.
At the same time, the surface of the number 4# composite coating has erosion points and appears white, indicating that the dense layer has been broken.

It has been demonstrated that the additions of a few atomic percent of Cr or W to g-TiAl shifts the phase stability drastically and creates relatively fine-grain microstructures consisting of a2+b+g in three phases.
When Ti-Al-Cr and Ti-Al-W phase diagrams are compared, the a2+b+g three-phase co-existing region shifts toward the Ti-Al binary side with an increasing atomic number[4].
According to the microstructure observations, the Ti-Al-W specimen consists of relatively fine grains, consisting of a2, b, and g in three phases.
Apparently, the EDS mapping indicates W atom segregation in the b phase grains, which create the Cottrell atmosphere at the core of the edge dislocations; consequently, additional stresses would be necessary to escape the atmosphere.

Strength is considered to be developed by the bonding of the finer fractions of particles to each other, and to the surfaces of the large grains.
Y is a dimensionless number, which is dependent on the geometry of the loading and the crack configuration with L/D ≈ 8, A0=+1.96, A1=-2.75, A2=+13.66, A3=-23.98, A4=+25.22 [14].
Fig. 1 shows a general microstructure of an alumina-mullite-zircon refractory material with a map distribution of each element, where crack formation was in general observed around alumina and mullite grains.
A significant difference on the coefficients of thermal expansion, which were 8.18x10 -6 °C-1 (from 0 to 1027 °C) for alumina, 5.13x10-6 °C-1 (from 25 to 1000 °C) for mullite and 7.59x10-6 °C-1 (from 25 to 1000 °C) for m-zirconia [16], led to large tensile hoop stresses and crack development between alumina, mullite and zirconia grains, during cooling from fabrication temperature of 1500- 1650 °C.
This is because the crack tip stress field around alumina-mullite grains can cause the zirconia particles at the crack tip to undergo a phase transformation causing expansion, where the volume expansion can squeeze the crack shut.

These expectations have recently been confirmed by a number of experimental studies [10,11,12].
But with the higher PTW content, the wear mechanism of PTW/PTFE/PES/PPS composite becomes grain abrasion (see Fig.5(d)), because excessive PTW might be pulled out and broken into grains between the two friction surfaces.
So a conclusion can be drawn from the above that the wear mechanism of the composite is changed from the micro-cutting plus adhesion wear to grain abrasion with the increase of the PTW content.
(3)With the increase of the mass fraction of PTW, the wear mechanism has changed from adhesion wear to grain abrasion.

The hardness is very important mechanical properties of natural and CVD diamonds, a great number of papers reported their measurement [6-8].
The diffraction peaks are significantly broadened due to the very small grain sizes.
Using the Scherrer formula [10], the grain size D of 13.8 nm is obtained from the half-width value of the (111) diamond peak.
This small amount of graphitic carbon in our films may exist in the grain boundaries.
The average grain size and surface roughness is approximately 14 nm and 11.8 nm.

For the DieMag211 alloy a number of externally solidified grains were observed in the microstructure, as represented by the large dendrite in the bottom left-hand corner of Fig. 1a.
In addition, the grain size decreased as well.
The variability in the elongation of DieMag211 at room temperature is probably related to the variability of the amount of externally solidified grains within any particular specimen.
Microstructure analysis revealed that with an increasing amount of alloying elements more secondary phases precipitate and the grain size decreases.

However, solid-state reaction method has some unavoidable disadvantages, such as the processing conditions fail to allow for easy control of microstructure, grain size or shape of the resulting powders [7, 8].
In recent years, with the development of science and technology in the field of materials, a number of wet chemical synthesis methods have been developed and successfully used for the preparation of YAIG nano-sized powders, such as the sol–gel method, hydrothermal synthesis, spray thermal decomposition and metal-organic preceramic processing.
Although the sol–gel method has some advantages, e.g. low-temperature synthesis, possible formation of powders with uniform grain morphology and achievement of homogeneous multi-component films, and has been successfully used to obtain undoped and rare-earth doped YAG phosphors, it has some disadvantages, such as hard controlling the pH, expensive starting materials and long-reaction time, all of which have limited its mass production.
Besides, the grain diameters are homogeneous and dispersibility is favorable.
With the increase in of sintering temperature, the crystalline grain of YAG powders was enlarged and the crystallite shape was changed from irregular to regulation.

However, the deposition time was too long; the greater ZnS grains deposited on the surface would introduce the scattering effect to deteriorate the optical transmittance.
The size and number of defects in 1.01.52.02.53.03.54.04.5 0 20 40 60 (αhν)2(1010eVcm -1) hν(eV) (c) (d) (a) (b) Fig. 1.
On other hand, in the lower NH4OH concentration conditions, for instance at 0.5 M, an enormous amount of ultra-fine grains with average size of 30 nm were present in the ZnS films.
The grain growth in the ZnS films became substantial when the concentration of ammonium hydroxide increased.
The average grain size was approximately 200 nm under the NH4OH concentration of 3M.