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Grain sizes were recorded after ECAP using electron back-scatter diffraction (EBSD).
Experimental results In the as-received condition, the grain size of the alloy was ~44 mm.
Fig 1 (right) shows the microhardness versus number of HPT revolutions.
Fig. 1 Microhardness versus number of passes after processing by ECAP (left) and number of revolutions of HPT (Right).
Fig. 2 Coefficient of friction versus number of Fig. 3 Wear rate versus number of ECAP ECAP passes for the two loading conditions [5].

Results and discussion 3.1 Mechanical properties and grain interior micro-structures of the Al-Li alloys Fig.1 shows the strength of the Al-Li alloys as a function of T6 aging time at 175°C.
As 0.72% Zn is added to the Al-Li alloy, the precipitate types are not changed, the strengthening precipitates still consist of a large number of T1 and d¢ precipitates and a small number of q¢ precipitates (Fig.3).
The dark field TEM image (Fig.3-c) shows that the Zn-contained Al-Li alloy possesses higher T1 precipitate number density and lower T1 size than the Zn-free Al-Li alloy.
According to Kinetic Monte Carlo simulation, the combined addition of Mg and Zn resulted in the formation of a large number of Zn-Mg-vacancy co-clusters in the initial aging stage [6].
Mainly due to this factor, the T1 precipitates in the Zn-contained Al-Li alloy are smaller with a higher number density than those in the Zn-free Al-Li alloy, as indicated by Fig.2 and Fig.3.

Figure 7 shows FeB concentrations measured for a number of ingots.
Average grain size is about 150 µm.
Grain size and grain boundary recombination.
In [22] grain boundaries were described by a barrier height and a space charge region around the grains.
The multi-crystalline silicon work at ECN is supported by Novem under contract number 146.110-020.1 and 2020.01.13.11.2002.

Thailand is the country produced the largest number of HDDs.
To increase HDD areal density, current research interest is on reducing the grain size of the media, decreasing the head flying height, improving read-back signal integrity, using patterned media, optimizing head performance, increasing both the number of platters and of the head gimbal assemblies (HGAs), employing a femto slider, etc.
The higher the disk rotational speed, the higher the number of particles generated.
The effect of Brownian motion is also ignored because of the high Peclet number of the particle.
Lastly, the particle trajectories and the number of particle trapped by the circulating filter were determined.

Studies shown that adjusting electroforming process parameters, and applying ultrasonic, additives and complexing agent will have different level effect on the metal casting layer grain size [4-8].
It will lead to crystal nucleus smaller, nucleation number and rate increasing, thereby to reducing casting grain size and result in the nickel casting layer surface morphology and reflective coefficient improved [13].
With the same intensity, the cavitation bubble numbers created by 40 kHz ultrasonic are more than that by 20 kHz ultrasonic, and compared with lower cavitation strength and stronger penetrating power.
When current density to be 4A/dm2, grain arranged for the smoothest, regularity, and size reaches the minimum, reflective coefficient arrived to the highest, which are shown in figure5 (a), (b).
However, when the current density to be over 4A/dm2, concentration polarization phenomenon on the cathode surface is obvious gradually, the increasing amount of hydrogen evolution bring about grain size began to growing, nickel casting layer surface appearing black, burning or loose phenomenon accompanied with different size stomatal, which caused grain arrangement dislocation, uneven, irregularity appearing, and reflective coefficient decline gradually.

The number of turns and the pressure were selected since previous papers reported successful consolidation of copper chips [21] and titanium powder [22] with these parameters.
Optical microscopy images of the center of the disc of CP-Mg chips processed by different numbers of turns of HPT.
Higashi, Ductility enhancement in AZ31 magnesium alloy by controlling its grain structure, Scripta Materialia 45 (2001) 89-94
Langdon, The influence of grain size and strain rate on the mechanical behavior of pure magnesium, Journal of Materials Science 51(6) (2016) 3013-3024
Langdon, Principles of equal-channel angular pressing as a processing toold for grain refinement, Progress in Materials Science 51 (2006) 881-981

It was observed experimentally that in a number of systems preliminary MA of the charge mixture brought about a decrease in both the ignition (Tig) and combustion (TSHS) temperatures along with changes in the SHS wave velocity and an increase of the conversion degree (η); in some cases MA changed the phase composition of the final products.
For vacancies Ev = vA f v cNH∆ , (4) where f vH∆ is the enthalpy of vacancy formation (1.40 eV for Ni and 0.76 eV for Al [14]), NA is the Avogadro number, cv is the vacancy concentration.
The energy per unit interface area (γgb) associated with boundaries of nanograins was determined for Fe at the grain size a = 10 nm: γgb = 0.16 J m-2 [16].
The interface area can roughly be estimated assuming that cubical grains are stacked into a simple cubic lattice.
Hence the energy of grain boundaries per one mole of a metal is Egb = 3γgbµ/(ad), (5) and for nanograined Fe we obtain Egb = 340 J mol-1 (2.2% of the melting enthalpy), i.e. the contribution of this factor into the total stored energy is small.

In addition, a small amount of ferritic grains was found embedded either between pearlitic colonies or at the pearlite-graphite interface.
The larger scatter found with the latter is attributed to soft ferrite grains scattered in the matrix.
To further explore the EBSD results, LAGBs were extracted from EBSD maps measured over a large depth and a so called LAGB density is calculated by divining the number of observed LAGBs with the total number of observations excluding void points (points that could not be indexed) at each measurement depth.
This is attributed to a higher density of HAGB related to the refinement of ferrite grains by shot peening, see Fig.4.
At greater depth, the LAGBs between pearlitic grains (Fig. 1(e) and (f)) become dominant and the averaged LAGB would approach the value calculated from unpeened samples.

A large number of distinct solid lubricant particles can be added to the metallic matrix.
For the samples sintered at 1150 °C properties such as, tensile strength (EMIC DL 2000) and Vickers microhardness (ASTM E-384, 100 kgf, LECO AMH 43) as well as the resulting grain size (ASTM E112-96 - intercept method) were also measured.
Some authors reports that sulfur has a higher coefficient of diffusivity in iron than Mo and even higher than the self-diffusion of iron, for the grain boundary and volumetric diffusion [10,11].
The grain size (ASTM grain size number) is also reduced for these samples; this may be a result of the restriction of grain boundary movement by the second phase (iron sulfide) during sintering [14].
For the sample containing 9% of MoS2 the liquid phase penetrates between the grains, assuming a shape factor far away from the perfect sphere.

The results suggest that the as-prepared coatings possess fine grains, little porosity and with hard-phases (CrB, Cr7C3, Ni3B) dispersed within the substrate (γ-Ni,).
The versatility of SPS allows very rapid densification to near theoretical density in a number of metallic, ceramic and multi-layer materials[7-9].
It shows that the coatings have fine grains, low porosity and with black and gray hard-phases dispersed in the substrate.
The grains near the transition layer are a little coarser, and some tiny voids can be observed.
Conclusions can be drawn as following: 1) The structure of Ni60 coatings prepared by SPS possess fine grain, low porosity with hard-phases (CrB, Cr7C3, Ni3B) dispersed uniformly in the substrate (γ-Ni,).