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SEM with energy-dispersive spectroscopy (EDS) showed elemental mapping of unreduced and reduced films, revealing micro grain size faceted particles of NiO and Ni, while smooth and much larger YSZ grains were also observed.
These thinner cathodes need higher porosity to improve gas diffusion through the electrode, and improved microstructure and phase dispersion to increase the number of available reaction sites or triple phase boundary length.
The thickness of the electrode is determined by the number of layers applied, as well as on the mesh size of the screen used for printing.

When the annealing temperature continues to increase, the recrystallized grains will merge with each other and grow, and forming a larger equiaxed grains structure (Fig. 1e ~ 1h).
After the recrystallization is completed, the grains will grow driven by the reduction of interface energy.
As the annealing temperature increases, the alloy undergoes recovery, recrystallization and grain growth.
A large number of research results show that the heat treatment process significantly affects the shape memory performance of Ti-Ni based SMAs.
The annealed Ti50Ni47Fe3 alloy undergoes recovery, recrystallization and grain growth[48].

The measurements were taken at three different points indicated by numbers on the micrograph (Fig. 2).
Two distinctive features in grains were observed: ZnO grains and agglomerated grains labeled as 3 and 1, 2 in Fig. 2, respectively.
Densification within the agglomerated powders is higher because of the shorter diffusion distances of atoms along grain boundaries and from grain boundaries to lattices.
This strength may be due to neck formation between the grains.
Necking of ZnO grains started locally at the sintering temperature and was shown in Fig. 2.

There is a number of factors that are reported to affect geopolymerisation.
As it is observed, both samples consist of two distinct phases: the first one is in the form of grains and the second one is the matrix binding the grains.
The EDS microanalysis of the grains showed that their composition is very close to the composition of the starting material and therefore it is concluded that the grains are unreacted slag particles while the matrix is the product of the reaction between the slag and the activation solution.
The activation solution of geopolymer sample with Si/Al=2.5 did not contain either Si or Al, so the dissolved Si and Al comes only from the slag grains.
In any case, the formation of nucleation sites and possibly of C-S-H phase results to the removal of Si and Al from the reacting solution, increasing in this way the dissolution of Si and Al from the slag grains.

Group Specimen Number Welding feed rate (mm/min) Tool rotating speed (rpm) A 1 2 3 45 56.4 67.8 2000 2000 2000 B 4 5 6 56.4 56.4 56.4 2000 3000 4000 3.
Optical microscopy revealed typical elongated shaped grains in the base material resulting from the process, as showed in Figure 5.
The stir zone presents particularly fine equiaxed grains, resulting from recrystallization.
Figure 6 highlights part of the SZ featuring fine equiaxed shape grains opposed to the recovered TMAZ, which is characterized by deformation and different grain orientation.
The weld regions show the distinct microstructural regions including the stirred zone, the grain-refined region, and the boundary region that separating the base metal and HAZ.

The electrochemical performance of this material, including reversible capacity, cycle number and charge-discharge characteristics, exhibits better.
That carbon made surface irregularity and inhibit LiFePO4 grain coarsening can benefit to the increasing of the specific area of cathode, extraction-insertion of lithium ion, close contact between cathode and electrolyte and the improvement of the conductivity between particles.
For grain agglomeration of LS700, it is likely that the growth of large particles leading to little intercalation-deintercalation of lithium.

The magnetic loss increases remarkably when work temperatures are exceed the Tmax, the structure and chemistry of the grain boundaries (GBs) should provide a strong influence on Hc [16-19], which prevent the future application of the magnets, and a number of investigations attempted to correlate the GB structure/chemistry and Hc [18, 19].
Before annealing, the grain boundary of the magnet is not obvious in the as-sintered magnets, but after tempering, the grain boundaries are clearly visible in the annealed magnets.
Meanwhile, the grain boundaries in the annealed magnets have a great brighter contrast than those in the as-sintered magnets.
The segregation of Nd+Pr can be seen at the grain boundaries, but there is no distinguished Nd-rich phase layer.
Other researcher think that the Nd-rich phases are nonmagnetic, which isolates the Nd2Fe14B grains magnetically [7].

In addition, NiO nanoparticles tend to have a high density of grain boundaries due to their reduced grain size compared to their bulk state.
This increases the number of charge carriers (electrons or holes).
Charge carriers better accumulate at Ni1-2xMgxCuxO grain boundaries due to larger grain sizes and decreased resistance of grain boundaries [44,45].
Doping also contributes to microstructural modifications where higher Mg, Cu, and Ru dopant concentrations reduce grain boundary defects and boost grains’ connectivity [58].
Thirdly, Cu ions affect the grain boundaries by lowering their resistive nature more effectively than Ru ions by improving grain connectivity [63,64].

This is illustrated on Fig.2 where the evolution of the metal loss is represented as a function of the number of thermal cycles for three different grades.
F14Nb F17TNb F12T Number of cycles Metal loss (g/m2) Fig. 2 : Evolution of metal loss with respect to the number of thermal cycles during a cyclic oxidation experiment.
To reduce the grain growth during high temperature holdings, extra addition of niobium is performed leading to an intermetallic precipitation.
Depending on the temperature, a part of the precipitation occurs along the grain boundaries ; combined with a fine intragranular precipitation, it strongly slows down the grain boundary mobility.
Assuming that a twin is an impenetrable obstacle to the dislocation motion, the average twin spacing contributes to the limitation of the mean free path, jointly with the initial grain size, d, and the dislocation density, �, generated by the deformation.

The torsion tests directly provide the curves of torque versus number of turns.
The effective strain at the outer fiber, ε, and the strain rate, ε , can be obtained by means of the following expressions [6-7]: ε =2πrN/(L√3) (1) and ε=2πr N/(L√3) (2) where r is the sample radius, N is the number of turns, N is the number of turns per second and L is the gage sample.
Results and discussion The microstructure of the initial Al 2024-T351 alloy [5] consists of recrystallized grains, with spacing between high-angle grain boundaries (HABs) in the normal rolling direction of about 7.4 mm.
The fraction of high-angle grain boundaries (fHAB) was 92%.
However, temperatures higher than 500°C are not realistic since local melting at grain boundaries could occur.