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The number of modeling steps is 220 – 270, with a step of 0.5 s.
As a rule, such a level of accumulated strain in copper alloys and aluminum alloys leads to the formation of a structure of a grain type with a grain size of below 1 μm.
Zhu, Continuous processing of ultrafine grained Al by ECAP–Conform, Materials Science and Engineering.
Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog.
Valiev, Processing ultrafine-grained aluminum alloy using Multi-ECAP-Conform technique, 2014 IOP Conf.

SEM patterns of the ZnS thin films produced by various radio frequency power The SEM surface images of the ZnS films with sputtering pressure 0.6Pa produced at different powers are shown in Fig.1.For the ZnS film with the power of 100W, the surface morphology consists of a large number of crystallites with visible pores, as shown in Fig. 1a.
Growing at higher sputtering power results in a change of the grain shape and an decrease in the pores over the films, as shown in Fig.1c.It can be clearly seen that the ZnS films are uniform with small grains,and the particle size parallel to the substrate surface is found to increase from 20 nm to 50nm with the power increasing.The micrograph demonstrates that higher power will enhance energies and mobilities of the particle,the grains of the films become large and dense due to the big unit cell.While up to 400W, the grain size of the ZnS films become larger notably.Compared to particle size and consistency,the thin film deposited at 300W is homogenous ,smooth and dense,is most suitable for butter layer material,which is better than that of CBD[3].
with various radio frequency power of 100W,200W,300W,and 400W,respectively.All the films exhibit the dominant peak centered at 2θ=28.027º,according to the JCPDS cards,which corresponds to the diffraction from the (111) plane of the β-ZnS with the crystal spacing 0.318 nm.From the intensities of ZnS (111) peak,it can be found that the ZnS thin film has a (111) preferred orientation.The relative intensity of the ZnS (111) diffraction peak increased gradually as the power was increased up to 300W,showing that the growth of crystallization is very well.It can be clearly seen that the FWHM valuedecreases markedly from 0.616° to 0.576° with increasing the power from 100W to 300W.This means that the crystallinity of ZnS films becomes better by increasing the radio frequency power.Up to 400W,however,the FWHM value of the peak increases to 0.188°, indicating the deterioration of crystallinity of the films,which means higher power will reduce crystalline state of ZnS thin film and increase the grain
XRD diffraction patterns of ZnS films deposition with different sputtering pressure The XRD spectra of ZnS films sputtered at various pressure under the sputtering power of 300W are shown in Fig.3.As shown,a single diffraction peak at 2θ=28.54°is observed to emerge in this pattern,corresponding to the(111)plane of the cubic ZnS.This indicates that the ZnS thin film has a(111)preferred orientation.With lowering the pressure from 1.5Pa to 0.2Pa,the ZnS peak obviously becomes sharper,with the higher intensity,and the grain size become smaller.The reflection intensity for the sample with the ZnS buffer layer 0.2Pa is stronger than that for any other sample.Thus,reducing the pressure is helpful to improve the crystalline states of ZnS thin film. 3.3Optical properties The transmission spectra of ZnS films deposited at 300W are shown in Fig.4.
Apparently, the steepest optical absorption edge is observed in the ZnS thin film obtained by sputtered for 0.6Pa , indicating its good crystallinity and homogeneous distribution in the film composition and grain size.The band gap information is given by the following formula [4] , (1) where λ is the steep jumping wavelength in Fig. 4.When pressure is 0.6Pa,the absorption edge takes place at 354 nm,corresponding to Eg is 3.50eV.When pressure is 1Pa,the sharp absorption edge takes place at 371 nm, corresponding to Eg is 3.34eV.The band gap of zinc blende cubic structure β-ZnS lies in the range 3.5-3.6eV,the band gap of hexagonal wurtzite structure α-ZnS is around at 3.8eV.The calculated results have shown the ZnS has a (111) orientation while the sputtering power and pressure is 300W and 0.6Pa.As we can see,the numerical value less than3.6eV,it's caused by sulphur defect in the course of growth [5] .

The micro–nano hybrid powder specimen had a fully dense microstructure consisting of grains that were less than 10 µm in size at 1200⁰C that comparable with sintering of micro powders at 1350⁰C.
Micro powder grains rarely grow because of the inhibition effect of the rapidly growing nano powder grains [4].
By using nano powders, hardness also increased from 182 HV to 221 HV due to the refined grains in the microstructure.
The micro–nano hybrid powder specimen had a fully dense microstructure consisting of grains that were less than 10µm in size at 1200⁰C.
Acknowledgement This work is conducted under project number: ERGS/1/2011/TK/UKM/01/8 in Universiti Kebangsaan Malaysia (UKM).

Fig.3 shows precipitation grains is spherical, evenly distributed in the substrate glass.
Precipitation of Na2Nb8O21 system constantly consumed doping composition in glass substrate along with the grain growth phase space around each direction in the process of grain growth.
So as the growth of the grain size, precipitation from the surrounding Na2Nb8O21 system phase energy is more and more weak, finally in the position of spherical produced the termination of crystallization area, lead to form spherical crystallization area.with the extension of heat treatment temperature, the grain number increase gradually.
Preparation of high content of crystalline phases and grain size distribution uniform microcrystalline glass needs crystal phase distribution of the residual glass phase and particle size are uniform relatively, in order to reduce the light scattering and reflection losses on transmission in the matrix.
The quantity of grain size increases gradually with the extension of the crystallization time.

In addition, columnar grains elongated toward the z direction appeared during the repeated melting and solidification that occurred during the EBM process.
An increase in the beam current of the incident beam enlarged the α grains and increased the relative density, resulting in the related Young’s modulus of the products.
In addition, columnar α+β grains continuously grow through the stacking layers along the z direction.
Based on an EBSD analysis, it was found that the elongation of crystal grains was caused by the preferred β phase growth along the z direction.
(2) The porosity and grain sizes of Ti–6Al–4V alloy products fabricated using EBM can be controlled based on the energy density depending on the electron beam current

However, the mechanical characteristics and microstructure features of a cold worked metal may be restored to their pre-deformed condition by a suitable heat treatment during which recovery, recrystallization and grain growth occur.
The amount of recrystallization is a function of time, temperature, and the degree of prior cold working [8].The grain size depends upon the temperature of recrystallization annealing, the holding time at this temperature, the degree of previous deformation, the chemical composition of the alloy, the size of the initial grains, the presence of insoluble impurities, etc [9].Mechanical properties of pure metals or undersaturated solid solutions depend on their grain structure (morphology and size, texture, misorientations) and dislocation structure (density, network, cells or sub grains, deformation or shear bands).
Table 2 Deformation percentage of the investigated alloys Deformation% Sample number 35.0 5005 36.7 5052 36.0 5251 37.0 5754 Some aspects of recovery kinetics and mechanisms, which have been mainly studied in pure metals [10-13] are still unclear or insufficiently documented.
On the other hand, the observation of microscopic mechanisms in dense dislocation tangles is difficult to perform by transmission electron microscopy (TEM).In order to address such basic questions; we have performed a number of physical observations for several recovery conditions on AlMg alloys, the basis of wrought work-hardenable aluminum alloys.
Due to the above-mentioned difficulties, a large number of property measurements have been performed simultaneously: electrical resistivity, specific mass, differential scanning calorimetric, X-ray diffraction line broadening, conventional and “in-situ” TEM, mechanical properties [15]. 2- Experimental work In this work, the used samples are brought from Aluminum Complex of Naga Hamady, Egypt, in plates form.

There is a decrease of the grain size with increasing BT concentration, suggesting that dissolving BT into NBT inhibits the grain growth.
The sintered ceramics have microstructure consisting of fine grains of about 1~2 nm in diameter, and present excellent crystallization, good compactness and clear grain boundary without obvious pores.
Other results by Min Chen [10] show that the doped BT can inhibit the growth of crystal grains and reduce the size of the NBT.
Compared with traditional solid-phase method, the grains of the NBT-BT synthesized by sol–gel combustion method are more uniform in shape and size.
SEM results indicate that the NBT-xBT ceramics are composed of fine grain (about 1~2 nm) without pores.

The sintering stage, however, has a number of challenges; most are associated with the high affinity of Ti for oxygen and nitrogen.
Compared to the uniform pore distribution in the MW-sintered sample, a number of large pores are observed at the centre of the conventionally sintered sample (Figure 6 a).
Straight grain boundaries are observed in both conventionally sintered and MW-sintered samples, indicative of the formation of polygonal α-Ti grains and significant sintering.
Pores are observed both within the grains and along grain boundaries.
However, quantitative measurements of the average grain size over 1000 grains from each sample confirmed the observation that the average grain size (80.4 µm) in the MW-sintered sample is larger than that (66.9 µm) in the conventionally sintered sample.

The microstructure of AZ91 base alloy (Fig. 1a) depicts indistinguishable eutectic and primary α – phases and eutectic equilibrium β – precipitates (Mg17Al12) along the grain boundaries as well as adjacent to the grain boundaries.
Normally, fine size particles (<10 µm) are prone to grain boundary cluster and agglomeration because, the growth of the primary α-Mg grains pushes the particle towards the grain boundary besides, the high surface tension forces, due to large area/volume ratio at the interface and the small mass of the particles contribute to the agglomeration of the particle and their clustering at the grain boundaries [4, 5].
It is further noticed that the SiC particles are located at the grain boundaries and within the primary magnesium grains.
The lower CTE values obtained in AZ91/SiCp composite are attributed to more number of less CTE containing SiCp in the AZ91 matrix.
Vol. 17, Number 5, 725-729, DOI: 10.1007/s11665-007-9168-2

Introduction Complex studies of the mechanical behavior of metals and alloys have led to the establishment of a number of features, which in the fluctuating field of temperatures and strain rates, can be considered as structural-phase transitions.
It is obvious that the formation of a fine-grained structure during the phase transition and, as a consequence [8], its blurring with respect to temperature and strain rate, creates conditions for realizing the slippage mechanism characteristic of superplasticity along the grain boundaries [9].
In the cross section of the sample, an explicit elongation of grains having a plane-parallel “pancake” shape and banded structure was also observed (Fig. 2a).
It is established that the elongation of grains decreases with increasing degree of deformation and an increase in the rate of deformation.
The structure specified is identical for all deformation rates with equiaxial fine grains (Fig. 4c,d).