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The microstructure of the upper surface region of S1 consists of fine equiaxed grains and rapidly grown large grains as shown Fig. 3(a).
Journal Title and Volume Number (to be inserted by the publisher) (a) upper surface of S1 (b) center of S1 (c) upper surface of S2 (d) center of S2 Fig. 3 Microstructure of T6 treated bar Crystallographic details.
It can be clearly known that the large grains rapidly grow consuming the fine equiaxed grains during the solution treatment.
The inverse pole figures in Fig. 4 show the crystallographic orientation of fine equiaxed grains and rapidly grown large grains.
These results suggest that grain growth behavior during the heat treatment have some relation with crystallographic orientation of grains.

In order to lower interfacial stresses between copper and nickel, the microstructure of nickel was controlled to consist of grains with a mean size of 15 nanometers.
In the Cu electrodeposit, the as-deposited texture characterized by a relatively high <100>//ND and twin components transformed to be diffuse due to grain growth during annealing above 300oC.
This is attributed to a large number of twins conducting the as-deposited microstructure.
On the other hand, in the Ni electrodeposit, grain growth that takes place during annealing above 250oC corresponds to abnormal grain growth in terms of the scale change of the grain size.
This grain growth also transformed the as-deposited texture of strong <100>//ND into a diffuse texture.

The Effect of High Temperature Grain Refinement on the Isothermal Ferrite Grain Growth Kinetics in Steel S460 J.S.
Ferrite initially forms on grain boundaries before growing in to the austenite grains.
Similarly to the undeformed specimens (Fig. 2), the primary ferrite nucleates at the austenite grain boundaries and grows into the austenite grain
This homogeneous microstructure increased the grain boundary area and therefore the number of potential nucleation sites for the ferrite grains.
· The deformation step refined the prior austenite grain size, which in turn increased the ferrite grain growth kinetics due to an increase in the grain boundary area when compared to undeformed specimen

By now there exist a number of models describing the non-equilibrium grain boundaries.
The goal of the present study is to incorporate the spatially dependent diffusivity in individual grains into Fisher model of grain boundary diffusion.
The estimations of ΔS and Δd at T = 500 K for a number of FCC metals are given in Table 1 for T = 500 K; the linear dislocation density for non-equilibrium boundaries was supposed to be r = 108 m-1 which is typical for the SPD-processed materials [2, 4].
The numbers at the curves correspond to the distance from the source in units.
Finally, it should be noted that expressions – for layer activity (which represents an average concentration of tracer atoms in the selected layer) include three parameters: grain boundary width d, grain boundary diffusivity Dgb and bulk diffusivity value at the grain boundary-grain interior interface D1.

Thus, at average grain size of materials below ~100 nm, the plastic deformation may occur due to the grain boundary sliding (GBS) mechanism which reduces the grain size strengthening effect.
The average grain size is about 9 nm.
Commonly, atoms in Al GBs have a coordination number different from 12 of an ideal fcc lattice.
Therefore in order to create the computational cell for the NC Al-Co and Al-Mg alloys with the GB segregations, the Al atoms with the coordination number equal to 11 or 10 are replaced by the corresponding alloying atoms.
This process results in a grain growth.

Grain boundaries can therefore more easily break free from the particles than in purely two-dimensional systems, resulting in fewer grain boundary–particle intersections and a larger final grain size.
The dispersively distributed second phase particles in alloy inhibit the matrix grains growth so as to refine grains.[1-3] Experiences have proved that fine grain strengthening is the only way improving the toughness meanwhile improving strength.
Second phase particle generation technology During the initial stage of simulation, particles are generated according to the second phase particle’s shape, radius r and volume fraction f (area fraction f in 2D cellular automata model), orientation number value of 0 to distinguish from normal grain, and in the process the value keeps constant.
With a square particle as an example, its area can be obtained as long as its sides are determined, then can calculate total number of particles.
(2) Calculating the second phase particle numbers according to f : (4) Where, Stotal for total cellular area

During grain coarsening the average grain size increases.
The grain boundaries have an excess energy to the grain interior.
If the grain coarsening is described phenomenological it could be seen, that in the grain relations the small grains become smaller, and the big grains become bigger.
The difference came from the stochastic nature of the automaton and the finite number of the cells.
This happens due to the finite number of cells in the universe.

Under fatigue loading, the number of cycles to failure and its associated scatter increase when the loading level decreases.
The High-Cycle Fatigue (HCF) regime is thus characterized by a large scatter in the number of cycles to failure [1].
- This grain is surrounded by 6 surface grains and 7 sub-surface grains.
The grains exhibit a high crystalline anisotropy.
The distribution of the numbers of cycles to crack initiation widens as the loading decreases, as experimentally observed.

In the last decades a lot of research focused on ultrafine grain microstructures (grain size lower than 5 µm).
With increasing the accumulated strain, pancaking of deformed grains increase and so the number of nucleation sites for ferrite increases.
Heavy Austenite Deformation The mechanism of Heavy Austenite Deformation has been investigated by means of a number of tests on samples of steels 30MnB4 and 18MnB2, deformed of 50 % at temperature Ar3+70°C at two different strain rates (1 s1 and 30 s1) and two different prior austenite grain size (10 µm and 50 µm).
Increasing strain rate is not effective on grain size refining: on the contrary, ferrite grain size tends to increase when strain rate rises.
Microstructure of steel 30MnB4 with UF ferrite grain size 3.3 µm.

Their reliability is however critical as they control an increasing number of on-board applications.
Pulses are 120 Amp; components are kept at 25°C. ton: pulse duration; Nf: number of cycles at failure (see text); 1fN : number of cycles at which the first component (out of the batch of 10) failed.
It should be emphasized that the number of fatigue cycles is not a pertinent parameter: indeed it is observed that the evolution of RDSon is not directly connected to the number of fatigue cycles (Fig. 2b).
stressed components for which RDSon is still in the specification limit and consequently the delamination at the power die/heat sink interface is low) the mean grain size increases with the number of fatigue cycles, which suggests that grain growth in the source metallization may be a good marker for quantifying the ageing of these components.
However in failed components (RDSon out of the specification limit), the grain growth is much faster than in operational ones, even if the number of fatigue cycles is lower.