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And when Gd content increases to 1.2wt.% and 1.5wt.%, the number of precipitates increase and they distribute along grain boundaries as discontinuous net microstructure, as shown in Fig.2(d-e).
As shown in Fig.1(a), the grains in Zn-25Al-5Mg-2.5Si alloy are coarse and adding 0.4wt%- 1.2wt% Gd, the grains become smaller(Fig.1c-e).
According to this relationship, the smaller the grain size, the higher the strength.
So the tensile strength of alloy with the smallest grain size should be the highest when Gd content is 0.8wt.%.
When Gd content is 0.8wt.%, the optimized grains refining effect on the alloys is obtained

The initial microstructure with prescribed grain size was generated by a normal grain growth algorithm.
The inherently poor workability of Mg and several of its alloys is due to the limited number of slip systems associated with the hexagonal close-packed (HCP) crystal structure.
Secondly, nucleation of DRX only occurs on grain boundary (including primary grain boundaries and R-grain boundaries), all other nucleation mechanism is not considered.
The grain growth adopts the probabilistic transformation rule, so the growing grains reach approximately globular shape.
The mean radius of primary grain , is defined as (1) where is the side length of hexagonal cellular, is the number of CA cells, and is the number of primary grains.

Different Dual Phase steels were processed with ferrite grain size between 0.7 µm and 4 µm and martensite islands dispersed along the grain boundaries of the ferrite phase.
A name was given in relation with the size of the ferritic phase : CG for Coarse Grained, FG for Fine Grained and VFG for Very Fine Grained.
The ferrite grain size, martensite grain size and martensite volume fraction are provided in Table 2.
Ferrite grain size (df), martensite grain size (dm) and martensite volume fraction (Vm).
The agreement is not so good at the lowest depth for which a small number of representative indentations was performed.

Additional to what Beck could see, the 3DXRD approach allows complete 3D in-situ monitoring of the growing grains.
Figure 2: The initial, A and C, and final, B and D, 3D shape of the grain as observed by the 3DXRD microscope.
The Journal Title and Volume Number (to be inserted by the publisher) 3 shape of the grain measured was reconstructed by simply stacking the cross sections of the grain as seen on the images, i.e. stacking the diffraction spots obtained after background subtraction and normalization to the synchrotron current.
Since the grain had already migrated to the surface of the sample growth was observed in all regions except the top region.
Complete 3D maps of growing grains are obtained with a time resolution in the order of minutes. 2.

Textured ZnO-Based Varistors via Templated Grain Growth Ender Suvacı, İ.
Anisometric elongated grains suggest anisotropic grain growth in this sample.
In addition, size of matrix grains increased from 0.2 µm to 6-8 µm.
In addition, as matrix grains grow, driving force for the template growth, which is arisen by surface curvature difference between templates and matrix grains, decreases.
Acknowledgments The financial support from Anadolu University Scientific Research Projects Commission (contract number: 020234) for this study is gratefully acknowledged.

As shown in Fig.3 (a), a large number of deformed austenite microstructure and a small amount of recrystal grains with size of 5~10mm were observed when the strain rate was 1s-1.
In the case that the strain rate was 0.1s-1 as shown in Fig.3 (b), the number and size of the recrystal grains increased compared with that obtained at the strain rate of 1 s-1.
When the strain rate was 0.05 s-1, the uniform grains with size of approximately 20mm as well as a small number of deformed grains were observed as shown in Fig.3 (c).
As shown in Fig.4 (a), a large number of deformed austenitic grains and a small amount of recrystal grains were observed when the deformation temperature was 900℃.
In the case that he deformation temperature was 950℃ as shown in Fig.4 (b), the number of fine recrystal grains increased obviously.

ECAP at moderate-to-high strains leads to the formation of a bimodal grain structure with grain sizes of around 1 and 8 µm and volume fractions of 0.3 and 0.6, respectively.
Factors affecting grain refinement, as well as the mechanisms of deformation-induced grain formation in such materials, are currently being debated and are not clear.
Dark regions arrowed in (c) and (d) are composed of fine equiaxed grains with the grain size of around 1 µm.
The other is composed of relatively coarse grained regions with grains of around 8 µm, which maintain an essentially equiaxed shape after each ECAP pass.
It is known [4-7] that evolution of deformation bands can play a key role in the occurrence of grain refinement during IPS in some metallic materials; in other words, a gradual increase in the number and misorientation of these bands and their conversion into high-angle boundaries can result in the formation of a new grain structure through cDRX [4,6,7].

Fig. 1 shows the general algorithm for Markov Chain - Monte Carlo based model of intergranular crack propagation where N is the number of Monte Carlo steps, n is the number of different GBCDs, M is the maximum crack length and Lavg is the average crack length.
[Rh] = [V(A1), V(A2), V(A3), … … … …, V(An)] [Ri1] = [V(B1), V(B2), V(B3), … … … …, V(Bm)] [Ri2] = [V(C1), V(C2), V(C3), … … … …, V(Cm)] n = number of type 1 TJ m = number of type 2 TJ TJ type 1: T11(i) = 1 - V(Ai) T12(i) = V(Ai) i = 1, 2, 3, … … …, n TJ type 2: T22(j) = 1 - {V(Bj)+V(Cj)-V(Bj)*V(Cj)} T23(j) = V(Bj) T24(j) = V(Cj) j = 1, 2, 3, … … … …, m C1 1 3 4 A1 B1 2 Table 1: Transition Matrix for Fig. 2 Table 2: Grain Boundary Ranking for HM The initial crack location can be expressed in matrix form of the same column size of Tr: p0 = [1 0 0 0]
The susceptibilties (hypothetical) of grain boundaries are given in Table 2.
Contrary to the equiaxed hexagonal grain structure, the voronoi microstructure (see, e.g.
It will enable one to incorporate different grain shapes, grain size distributions etc. in the model microstructure and, determine their effects on the crack propagation behaviour.

Cracks on a broken section of DWTT samples can (a) penetrate the coarse grains directly, (b) propagate in Zig-Zaga way in the fine grains, and (c) be around the boundary of original austenite grains.
In order to establish the steel processing for stable and high quality steel plates, especially to guarantee the DWTT property, a number of industrial trials were carried out for developing OHTP technology in Shagang.
A lot of continuous coarse austenite grains present on the middle of 1#sample, in comparison of small austenite grains in 2# sample.
In the case of X80 pipeline steel with acicular ferrite, the original austenite grain plays a key role for the fracture toughness because these grains are the effective grains when a fracture is taken place [5,6].
Fig.13 shows some crack propagations between coarse and fine austenite grains of 1# DWTT sample, in which (a) cracks penetrate the coarse grains directly, (b) cracks propagate in Zig-Zaga way in the fine grains, and (c) cracks are around the boundary of original austenite grains.

It is seen that twins can both expand, taking over an entire grain, or shrink, leaving completely untwinned grains.
Introduction During the last few decades, the world has seen a growth of applications of magnesium alloys in almost every field of today's industry, but a number of issues impose barriers to further expanding this market.
The most important one is its limited deformability caused by the hexagonal crystal structure of magnesium, which limits the number of active deformation mechanisms, especially at room temperature.
EBSD measurements showed that a number of untwinned grains are present with the initial orientation (c-axes perpendicular to the compression axis).
Schmid factors were calculated for grains containing expanding twins as well as for grains containing shrinking twins.