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At this time, a large number of quasi-solid-state atomic group had a good wetting function with nucleus, and the atomic group could develop into floating crystal quickly.
But in the process of solidification, latent heat still existed, so the grains could not grow the same way that equiaxed grains did , instead , they grew in a way between equiaxed grains and dendrite did, and finally the grains grew into rose-like shape.
The actual solidification process was a complex process of physical chemistry controlled by numbers of factors.
Even in a strong mixture convection, the melt was not a uniform and balance system, so grains might be in the shape of irregular or branchlike, and stirring may make grain collide and sinter, and then the grains could integrate into a big grain.
When the melt temperature drops to the liquidus level, the whole melt enters the state of undercooling immediately, and a large number of nucleation is formed

The microstructure comparison of ultrasound and general cast-rolling shows that: The grain size of general cast-rolled lead strip is big; the grain boundary is coarse and the organization structure is uneven.
However, the grain structure is refined, smaller grains and uniform organization structure is acquired with ultrasound treatment.
Therefore another technology is needed which can improve the crystalline environment and refine the grains.
A large number of domestic and international researches showed that the effect of cavity and acoustic streaming can break the big dendrite structures, refine the gains and enhance the mechanical properties of metals [10-13].
The acoustic streaming intensifies the movement of melt flow leading to the grains conflict with each other.

With increasing of TiB2 particles, the number of TiB2 particles smaller than 200 nm will increase in the grain, resulting in the increase of the capability of heterogeneous nucleus (in the grain), and nucleation is the main function of TiB2 particles at contents below 4.5%.
The globular grain on the bottom whose mean grain size is about 250mm and shape factor is 0.94 in Fig.8.
The globular grain also begins to melt into rosette grains on the bottom.
As the holding time increasing, dendrite grains are necked and remelted at first, then rosette grains melt and shrink into globular grains, finally the globular grains begin to grow, but the number of grains decreased and their mean grain size increase since some contiguous grains merge into bigger grains by coalescence and small grains disappear by diffusion through the solid phase.
As the holding time increasing, dendrite grains are necked and remelted at first, then rosette grains melt and shrink into globular grains, finally the globular grains begin to grow, but the number of grains decreased and their mean grain size increase since some contiguous grains merge into bigger grains by coalescence and small grains disappear by diffusion through the solid phase.

Mid-life stress amplitudes and the number of cycles to failure were exerted to calculate the cyclic stress-strain curve adopting the Manson–Coffin–Basquin and Ramberg–Osgood equations with respect to compatibility [6].
The average grain size (AGS) measured for more than 5000 grains varied only slightly between 0.7 and 1.6 µm depending on the Tp and CR reduction.
Blue grains = α’ -martensite DIM; yellow grains, coarse austenite (GS > 10 µm); green grains = medium-size grains (GS 3–10 µm); red grains = fine-sized grains (GS < 3 µm); black pixels, unindexed.
The reversion is fast and the grain growth minimal.
In Fig. 5, the stress amplitude vs. number of cycles to failure for annealed and cold-rolled Com-301LN and 690-60-56 structures was calculated from the strain-stress-lifetime data.

Although the number of valence electrons of a P atom is less than that of a Fe atom, the charge densities of the Fe-P bonds (Fe1-P, Fe6-P and Fe7-P) at 0% in the P-seg1GB model were higher than those of the Fe-Fe bonds (Fe1-Fe3, Fe6-Fe3 and Fe7-Fe3) at 0% in the clean GB model.
Olson, Nature of phosphorus embrittlement of the FeΣ3[10](111) grain boundary Phys.
Yamamoto, Theoretical tensile strength of an Al grain boundary, Phys.
Mabuchi, Bond mobility mechanism in grain boundary embrittlement: First-principles tensile tests of Fe with a P-segregated Σ3 grain boundary, Phys.
Heine, Effect of impurity bonding on grain-boundary embrittlement, Phys.

This was attributable to the formation of a high melting point Lu4Si2O7N2 grain boundary phase, which can be extensively grain crystallized during sintering.
Although Si3N4 grain shows slightly different thermal conductivity between a-axis and c-axis [10] (the c-axis corresponds to the grain alignment direction), the thermal conductivity of Si3N4 grain is much larger that that of SiO2 contained grain boundary phase [11].
Therefore, the ratio of Si3N4 grain and grain boundary phase in the material was key point for modifying the thermal conductivity.
Specific heat capacity, thermal diffusivity and thermal conductivity of the seeded and no-seeded Si3N4 ceramics Since the seeds addition and tape casting were employed in the fabrication process, the elongated Si3N4 grains grown from seeds were preferentially oriented parallel to the casting direction, resulting in both the number of grains per unit volume decrease and a decrease in the number of two-gain junctions [12].
The increase in number of the elongated Si3N4 and grain alignment was of benefit to the thermal conductivity.

An Atomistic View of Grain Boundary Diffusion MISHIN, Yuri1,a Department of Physics and Astronomy, MSN 3F3, George Mason University, Fairfax, Virginia 22030, USA aymishin@gmu.edu Keywords: Grain boundary, diffusion, modeling, simulations, molecular dynamics, correlations, liquid.
Introduction It has long been known that atoms diffuse in grain boundaries (GBs) orders of magnitude faster than in the crystalline grains, an effect which is often referred to as "short-circuit diffusion" [1].
(a) Probability distribution of the number of atoms in a cluster.
(b) Example of a log-log plot of the number of atoms in a cluster versus its gyration radius Rg.
Gust, Fundamentals of Grain and Interphase Boundary Diffusion (Wiley, Chichester, West Sussex, 1995)

The development of a coarse grained microstructure during the recrystallization has been noted and discussed by a number of authors but, the mechanism of grain control remains uncertain.
It appears that two factors: the peculiar distribution of high- (HAGB) and low- (LAGB) angle grain boundaries in the as-consolidated state, and the uniformity of the fine scale microstructure makes the nucleation of recrystallization difficult because the grain boundary junctions are strong pinning points, restricting the bowing of grain boundaries [7].
The grain structures in the tensile and compressed areas of sample 4 are presented in Fig.5.
It should be emphasized that the sub-micron grains are not low-misorientation cell structures typical in aluminum alloys, but true grains with large misorientations (see Fig. 5).
Subsequent heat-treatment leads to recrystallization into a very coarse grained microstructure [4].

Introduction Intergranular fracture is mainly induced by phosphorus (P) grain boundary segregation and loss of grain boundary cohesion [1-4].
Ohtani and McMahon [5] reported intergranular cracking occurs along prior austenite grain boundaries due to the continuity of prior austenite grain boundaries.
The samples showed fine and elongated grain structure along the RD and the prior austenite grain boundaries can no longer be recognized.
The 0.001 and 0.053 %P samples showed remarkable data scattering in absorbed energy at -100 and -150 ºC due to the increase in the number of delamination [13], where the cracks branch parallel to the longitudinal direction (//RD) of the impact test bars.
(b) The crystallographic orientations and (001) pole figures of numbered grains across the crack.

There has been a large number of engineering projects using coal gangue, such as road-building, backfilling foundation, and some of these engineering projects show that the roadbed backfilling with coal gangue have good effect.
Grain size distribution analysis test.
Grain size composition is an important factor[7] influencing the compacting degree.
This paper sampled gangue from the mine-spot, randomly sampled three groups of samples from the gangue deposited more than 5 years, respectively numbered 1, 2 and 3, and carried out indoor particle size composition analysis test on the samples.
Engineering properties and application of coarse grained soil[M].