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At present, basic research into SSM has been sent into operation and a number of SSM processes have been widely applied in industry.
The crystal grain that is at boundary of the liquid phase and the solid grain also is not clear.
In figure 1 (c), only solid grains remain and adhere closely because of liquid phase outflow to the surface of the specimen.
Under the lower deformation rate, the shape of deformed solid grain is flat oval.
With increasing the deformation rate, the shape of the deformed solid grain changes to polygonous and the broken-up degree of grains is more obvious.

They have shown that fatigue life increased with the growth of a vibration strike number by as much as 33%.
The average grain size of specimens was approximately 40 mm.
EBSD – images indicates that the twin length is limited by grain size.
It is well known, that grain boundaries prevent dislocation motion and its propagation deep into the material.
That is why the thickness of the hardened layer is determined primarily by the grain size of specimens and limited to one or two grains (Fig.1а).

One is the grain size effect, and the other is the feature/specimen size effect.
This effect shows that a material with smaller grain size demonstrates higher strength than one with larger grain size.
The other is the feature/specimen size effect and its interaction with the grain size effect.
With the trend toward increasing miniaturization, the number of grains across the cross section (N) decreases.
For example, in this figure, the tool stroke at step number 1 is 0.12 mm and it increases 5 μm at every step.

The shape memory effect,the classification and the principle of shape memory alloys are introduced.The performance features such as melting point,density, resistivity,thermal conductivity, thermal expansion coefficient, phase-change heattensile strength fatigue limit, grain size, transition temperature,lag size,one-way shape memory, two-way shape memory of Fe-based,Cu-based and Ti-Ni based shape memory alloys are researched in detail.
In the process of phase-change of SMAs, rigid, resistance, friction and number of sound waves of materials are changed.
Tab. 1 Structure, organization and performance of Fe-based shape memory alloys alloy composition martensite crystal structure characteristics of phase change recovery rate(%) Ms range /K Fe-Pt 25%(1) bct thermal elasticthermo elastic 40~80 280 Fe-Pd 30%(1) fct thermal elastic 40~80 180~300 Fe-Ni-Co-Ti Fe-33Ni-10Co-4Ti(2) bct thermal elastic 80~100 -150 Fe-Ni-C Fe-31Ni-0.4C (2) bct nnon-thermal elastic 50~85 77~150 Fe-Cr-Ni Fe-19Cr-10Ni (2) hcp/bct nnon-thermal elastic 25 — Fe-Mn-Si Fe-(28~33)Mn-(4~6)Si (2) hcp nnon-thermal elastic 30~100 200~390 Fe-Mn-Si-Cr Fe-28Mn-6Si-5Cr(1) hcp nnon-thermal elastic 100 300 Note:(1)Original number of molecules The original number of molecules (2)Number of molecules Study of martensite form, through appropriate alloy formation, iron-based alloys can be achieved in thermal elastic or non-reversible thermo elastic martensite change, which developed based on these two kinds of phase change of Fe-based SMAs.
Table 2 part copper-based shape memory alloy Tab. 2 Performances of Cu-based shape memory alloy Performance category Performance Unit Cu-Zn -AL Cu-AL-Ni Melting point ℃ 950~1020 1000~1500 Density Density kg/cm2 7800~8000 7100~7200 Resistivity Resistivity μΩ·m 0.07~0.12 0.1~0.4 The thermal conductivity Thermal conductivity W/(m·℃) 120(20℃) 75 Thermal expansion coefficient — (16~18)×10-6 (16~18)×10-6 Specific heat capacity J/(kg·℃) 390 400~480 Phase-change heat Phase change heat J/kg 7000~9000 7000~9000 Modulus of elasticity GPa 70~100 80~100 Yield strength MPa 150~300 150~300 Tensile strength (Martensite) MPa 700~800 1000~1200 Elongation (Martensitic) Elongation (Martensite) % 10~15 8~10 Fatigue limit MPa 270 350 Grain size Grain size μm 50~100 25~60 Transition temperature Transition temperature ℃ -200~170 -200~170 Lag size ℃ 10~20 10~20 Maximum one-way shape memory % 5 6 N=102 — 1 1.2 N=105 — 0.8 0.8 N=107 — 0.5 0.5 Maximum heating temperature(1h) ℃ 160~200 300 Damping ratio SDC

All billets were annealed at 773 K for one hour to give a homogeneous microstructure with an initial grain size of ~1 mm.
This is consistent with the well-established reduction of grain size that occurs in pure aluminum when processing by ECAP [4].
These weaker regions shrink with increasing numbers of passes and are essentially absent after 3 passes.
By plotting histograms of the numbers of fractions of the individual microhardness values within increments of 5 on the scale of Hv, as shown in Fig. 3, it is readily apparent that the hardness and the degree of homogeneity both increase with increasing numbers of passes.
Figure 4 clearly reveals the decrease in the weaker region of lower hardness with increasing numbers of passess.

It is clear the grain boundaries at low substrate temperature (in Figure 1 (a) and (b)), but the gaps between columnar grains decrease with increasing substrate temperature.
In fact, The average grain diameter (D) as a function of the temperature (T) can be expressed using following formula[16]: (1) where Qm is the activation energy of grain boundary, R is the the gas constant, and C is the proportional coefficient.
Therefore, when the substrate temperature increases, the grain size of the AZO films will increase.
Table 1 Grain size, diffraction peak position and FWHM of AZO thin films substrate temperature [oC] grain size [nm] 2θ [0] FWHM [0] 150 6.9 33.90 1.20 250 7.0 33.92 1.18 350 13.8 33.72 0.60 450 26.0 33.88 0.32 Effect of substrate temperature on the optical properties of AZO thin films.
If we assume that the Fermi surface is spherical, the following well-known formula is given[19]: (5) Here, is the BM shift, is Fermi wave number, is the reduced effective mass, ne is the carrier concentration and A is a scale factor.

It is obvious that a large number of reinforcement particles agglomerate in the matrix, indicating that the higher content of reinforcement are added, the more regions of agglomeration occurs.
The only distinct difference in the composites is the number of damping peak, as shown in Figs.9 (b), (c) and (d).
Grain refining technology of magnesium alloys [J].
Grain refinement of AlNp/AZ91D magnesium metal-matrix composites[J].
Fu.Grain refinement by AlN particles in Mg–Al based alloys[J].J.

The results show that the size of every grain in weld nugget zone which is made by the rotational tool with three-spiral-flute shoulder is nearly the same.
The degree of uniformity of grain made by three-spiral-flute shoulder is much higher than that made by inner-concave-flute shoulder or concentric-circles-flute shoulder.
The tetrahedral elements’ number of inner-concave-flute shoulder, concentric-circles-flute shoulder and three-spiral-flute shoulder are 21689, 21578 and 20681 respectively.
It is seen that the grain size in weld nugget zone is different for the joints attained by different rotational tool.
To the tool with three-spiral-flute shoulder, the every grain size in weld nugget zone is nearly the same, which verifies that the plastic flow of metal during FSW is enough.

Results showed necking of the nano-silver powder, which indicated the occurrence of sintering through grain boundary diffusion process.
Fig. 5, 500x Magnification of sintered 250 µm silver powder at 250°C Fig. 6, 1000x Magnification of sintered 250 µm silver powder at 250°C Fig. 7, 5000x Magnification of 250 µm silver powder at 250°C As highlighted [8] attributed this processes to the minimization of enthalpy in the form of Gibb’s free energy, which is related to the number of bonds.
Excess Gibbs free energy drives the agglomerate to become more compact (close packed structure), which results in an increase in the number of bonds.
In summary, the sintering process of Ag agglomerates goes through various sub processes such rearrangement of particles with sintering, growth of necks with neighbouring particles, coalescence of particles through grain boundary diffusion process, as shown in Fig.8.
In this study, the Ag agglomerates experience a number of changes to its morphology: (i) partial sintering was observed for the control sample at 1000C, predominantly due to rearrangement of weakly bonded particles; (ii) At 2500C, the agglomerates shows a more drastic changes in the particle morphology associated with the formation of necking and beginning of coalescence between particles.

Introduction Alumina (Al2O3) coating has been studied for a number of applications due to a beneficial combination of properties such as high hardness, chemical resistance and low thermal conductivity [1, 2].
Orthogonal experiment is one mathematical statistical method, by which the process parameters can be optimized while the number of experiments can be greatly reduced [6-9].
Experimental Materials and Slurry preparation The commercial α-Al2O3 powder with average grain size 100-150nm (SUMITOMO CHEMICAL CO., LTD.
Fig.6 gives the TEM images of as-sprayed coating, it was found that the coating was composed of regular-shaped grain with size of 200-300 nm.
Fig.6 HRTEM images of as-sprayed coating, (a) microstructure; (b) high resolution image of grain boundary.