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The grain boundary of the samples can be obviously observed, and the grain gradually decreases with increasing the WC content.
The grain of the 0%WC-Fe sample is coarse and big; the grain of the 10% WC-Fe becomes smaller, but some coarse and big grains still exist; while the fine grains is dominant in 20 %WC-Fe and 40 %WC-Fe.
When the grain growing up, the migration of grain boundary will be hindered by the WC particles always gathered in the grain boundary.
The grain boundary gets the pinning impact resulting in the decrease of the grain grown-up rate, and then the grains grow up to certain size and then stop.
At the same time, the WC particles gathered in the grain boundary also can block the grain grown up, and the more the number of WC has, the stronger the inhibition of the grain boundary generates, which results in the mechanical properties enhance with increasing the WC contents.

After the reagents have been injected, a large number of chemical reactions occur that reduce the harmful NOx to nitrogen and water. [2] The paper will deal with the impact of the described technology for reducing nitrogen oxides to one of the major secondary energy products, which is high-temperature fly ash.
Impact of SNCR on the morphology of fly ash grain.
Fig 2 Fly ash grains without the application of SNCR (enlarged 500, 1000 and 3000 times) The photos show almost regular spherical fly ash grains.
Small fragments of the original grains are then more likely to clump and form new, highly porous grains of irregular shapes.
Photographs of these fly ash grains have shown that the grains appear to have an irregular shape, resulting in increased water absorption.

Particular focuses are placed on coarse graining operation which authors developed and and time scaling as a remaining problem.
Hence, one needs to introduce an efficient recipe for performing multiscale calculations, which demands an appropriate coarse graining procedure.
In fact, these considerations are the motivations of performing first-principles calculation of PFM by introducing coarse graining procedure.
The size of a cubic block is L × L × L where L is an odd number bigger than 3 and the center of the block is designated as Lx.
However, these two figures are enough to cast a doubt on the simple averaging procedure as an appropriate coarse graining operation.

After modified by Bi, the alloy microstructure is changed into fine equiaxed grains from coarse columnar grains with more obvious refinement.
The dendrite arm of cast structure without Bi is well-developed with different grain sizes.
Ky is the pinning constant to measure the contribution of grain boundaries on strengthening, or the stress concentration factor to slip the end of the band. d is the average grain diameter.
Electric pulse modification can significantly refine the as-cast solidification structure of HSi65-1.5 silicon brass to make the columnar grain zone reduce or even disappear and expand the equiaxed grain zone.
Fine grain boundaries hinder dislocation movement, and the finer the alloy structure, the more the dislocation movement is hindered, which increases the dislocation numbers to start the dislocation sources as well as the stress so that the tensile strength is also increased.

Of course, to obtain the parent orientation a minimum number of different variants is required (see ref. [1]).
The highlighted zone shows the variants within a prior austenitic grain.
The number of data involved for determining the corresponding representative OR was always of several thousand orientations.
For each sample, several parent grains of different orientations were considered.
As for the other previous methods, it requires that a sufficient number of variants resulting of the transformation of a given austenitic grain be known.

Moreover, precipitates can influence grain growth, recrystallization and stress corrosion.
Evaluation of grain boundary precipitation provides important information on the effectiveness of grain boundary pinning, but also on potential grain boundary damage by nucleation and growth of brittle phases.
Case 2: Simulation of competing precipitation at grain boundary and dislocations in high-Mn, high-N stainless steel.
Moreover, simulation delivers the competition of different precipitate nucleation sites (grain boundaries versus dislocations).
Fischer, Mean-field model for the growth and coarsening of stoichiometric precipitates at grain boundaries, Modelling Simul.

This long time elevated temperature anneal resulted in substantial grain growth leading to a starting grain size of approximately 300 µm.
Figure 2 combines a large number of experiments at various times and temperatures to identify the recrystallization start and finish conditions.
The numbers beside each point give the measured recrystallization fractions.
The observed difference in the recrystallized grain size for the two levels of strain can be rationalized if the number of recrystallization nuclei per unit volume is taken to scale with the surface area per unit volume of the deformed grains.
The role of imposed strain on the recrystallization kinetics appears to be primarily through an increased initial driving pressure for high angle grain boundary migration as well as an increased number of nucleation sites on preexisting grain boundaries.

Measurement of the γ' specific connexity number NA(γ') at different stages of the creep deformation is an efficient way to quantify the evolution of the γ' phase connectivity [17].
During the 80's, a number of studies have accompanied the development of the PM disk superalloys in order to identify the ways to use the most of their potential.
As compared to linear grain boundaries, serrated grain boundaries decrease significantly the crack propagation rate in creep-fatigue conditions at 750°C.
Homogenization of the deformation was linked to a transition from intergranular crack propagation along the linear grain boundaries to a transgranular propagation in the alloy with serrated grain boundaries.
In the same time, keeping a small grain size allows to maintain a high level of tensile strength.

After the irradiation, the cylindrical grains were broken to smaller grains, and the compact cylindrical grains and their boundaries could not be seen.
The crystal grains became very small and approached to amorphous phase.
With introducing protons, the number of oxygen vacancies decreases, and the production of defect energy level induced by doping is baffled.
Therefore, the electric carrier number reduces.
Because the crystal grains become very small and approach to amorphous phase, the small crystal grains have more grain boundaries, which may behave as barriers against the electron moving inside thin film.

At lower annealing temperatures, the AFM shows nano-crystalline surface with grain size up to 100 nm.
The average surface roughness Sa was calculated as standard deviation of height h adopting the formula: where is average height and N is number of points.
The existence of the barrier between grains results from upward band bending on the grain boundaries due to the trapping of electrons in chemisorbed oxygen species [17] (Fig. 5-left).
Schematic representation of band bending at grain boundaries.
AFM study of the prepared thin films showed the increase in grain size and the roughness of the thin films.