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The analysis indicates that shot-peening can provide a large number of crystal lattice defects that facilitates boron diffusion in the steel, and the low temperature is apt to remain high dislocation density.
However, cold plastic deformation by SP takes place in the surface, leading to the formation of an extremely high density of dislocations and new grain boundaries subdividing the original coarse grains, which may serve as numerous fast diffusion "channels" for other atoms at the temperature.
Therefore, the boron diffusion in this experiment can be enhanced along the new grain boundaries and dislocations, because of a smaller activation energy than that in lattice.
The grain boundaries formed via severe plastic deformation are usually in non-equilibrium states that are associated with a higher stored energy or a higher density of defects, compared with the equilibrium grain boundaries.
This arises because SP can generate a large number of crystal lattice defects, which facilitates the boron absorption and diffusion.

Refining grains introduces more grains boundaries, which impede intra-grain dislocation motion, making the material harder to deform, and nanocrystalline metals with grain sizes of less than 100nm showed a exceeding strength than those of coarse-grained metals [4-7].
Large number of nanoparticles raise the density of stored dislocation which induces fierce strain hardening [11], leading to high tensile strength and high ductility. 2.
Due to fine grains, the strength of Cu–10Sn–2Zn alloy has been improved greatly.
Swygenhoven, Grain Boundaries and Dislocations, J.
Ramesh, Deformation Behavior and Plastic Instabilities of Ultrafine-grained Titanium, J.

A two step thermomechanical process (TMP) was used to develop a fine grained structure by sequential grain refinement.
The thermomechanical treatment produced a uniform grain structure with an average grain size of 11mm.
The average grain size was determined from measurements of more than 300 grains in both longitudinal and transverse directions.
The average grain size is 270 ± 10mm.
A careful examination of a number of AA2139 areas show that the alloy microstructure subjected to the thermomechanical treatment is reasonably homogeneous on the macroscopic level.

These effects are connected with the large number of dislocations formed during the plastic deformation.
The carbides and pearlite were located at the equi -axial ferrite grains boundaries.
The equi -axial ferrite grain size was G7/8 by national standard [6].
In ferrite grains and at the grains bounderies we could observed that the dislocation density increased by the cold work (Fig. 10).
After heavy deformation in ferrite grains appear subgrains (Fig.10 c) ).

The grains are well formed and the grain boundaries are clear cut.
For PTC-Y, there are many fine grains in the samples although the samples is well densified and hence suppression of anomalous grain growth and a large number of grain boundaries.
As for PTC-B, the number of the uniform grain is more than PTC-Y.
Fig. 4 shows that both of ceramic ruptures partly through the grains, others rupture along the grain boundaries.
Kahn, Preparation of Small-Grained and Large-Grained Ceramics from Nd-Doped BaTiO3, J.

At low fluid velocity, parallel jets flow at a short distance from the grains.
At 0.83 rps, all mineral particles are fully suspended. 1.33 rps represents the maximum number of stirrer revolutions under these experimental conditions.
However, as the average diameter of the sorbent grains decreases, the hydraulic resistance of the layer also increases.
It rinses the porous sorbent grains and fills the intergranular spaces of the bed.
New portions of the liquid encounter sorbent grains that are already partially saturated with copper.

While an older concept asserted that the tips of abrasive grains 2 dig into the transfer object 1 and move together with this thus cutting the workpiece 3, more recent studies on the mechanics of machining by lapping explain the removal of material by the rolling effect of the grain.
This latter indicator is influenced by a number of factors, amongst which the more important ones are workpiece material and form, abrasive material graining and concentration, the accuracy of the operation preceding lapping, the magnitude of the tooling allowance, the type of the deployed machine-tool, etc.
The best machining productivity is afforded by diamond grains, namely 2 to 4 times greater than productivity yielded by grains made from aluminium oxide or silicon carbide.
The presence of a large number of input quantities that influence the lapping process makes it almost impossible to use theoretical models for machining optimisation.
If all possible combinations of the various set points of the five input factors had to be tested, the total number of runs would be 24 • 31 = 48, which is undesirably great.

Introduction In recent years, Ni-Zn ferrites have been widely used for a large number of applications such as microwave devices, power transformers, and high density magnetic recording.
The coarsening is the process in which the larger grains grow up and the smaller grains disappear.
In a system, the small grains dissolve, and then separate out according to a tropism on the surfaces of large grains.
Consequently the large grains become coarsening.
At the same time, grain boundary became thin.

The analysis of this structure considering both real solid cross-sections and all elastic properties of wood by using specialized software, leads to a laborious work because of the high number of finite elements.
Thus is explained the important differences between the mechanical properties of wood in parallel and perpendicular to the grain directions.
In this paper, wood is regarded as a homogeneous material, with different elastic properties on three principal directions: parallel to the grain, radial and tangential.
The first method is not covered herein, and the second one is difficult because of the high number of finite elements.
The important differences between the elastic properties of wood in normal to the grain direction and parallel to the grain direction, lead to obtaining significant differences between the two analyses performed herein.

The suppression of grain growth in the final stage of sintering is achieved by exploiting the difference between the kinetics of diffusion in the grain boundary and the grain boundary migration rate controlled.
The samples milled presented a larger grain growth and when the milling time is increased, grain sizes also are higher.
The agglomerates formed during milling lead to the formation of coarse zirconia grains, as can be seen in the micrographs shown in Fig. 5, and thereby the pinning effect of grain boundaries is reduced, and the alumina grains tend to grow more.
The suppression of grain growth, but not densification is consistent with a network of grain boundaries anchored by triple junction points, which has higher activation energy for the migration than grain boundaries.
(a1)(a2) (b1)(b2) (c1)(c2) (d1)(d2) Fig. 5 – SEM micrographs of the nanocomposites in different conditions: The letters refer to times of high energy milling being (a), (b), (c) and (d) of 0, 3, 5 and 7 hours and the numbers indicate sintering the shape being (1) in stages and (2) conventional.