Search results

The decrease in the grain size being 27%, 26% and 28% respectively, which indicates that Ti+B is better refiner than Ti; although Boron itself is not a grain refiner.
If the superplastic deformation can be achieved by further plastic deformation at room temperature, this will help in reducing the number of stages in forming processes when large strains exceeding the strain at plastic instability are required.
The addition of Ti or Ti+B to Mg-AZ31 alloy resulted in grain refinement of its structure.
The most refined structure was achieved by extruding the Mg-AZ31 grain refined with Ti+B.
Extruding Mg-AZ31 grain refined by Ti and Ti+B resulted in increase of their ductility.

Introduction Recently, ultrafine grained (UFG) materials with grain size less than 1-m have been studied extensively, since they are expected to provide high strength without the degradation of toughness.
Although the authors do not have physical insight at the moment, it is expected that the small grain size including subgrain width would inhibit the formation of dislocation cells within grains.
Fig.5 TEM micrograph of 5083 Al alloy, cryo-rolled with 85% reduction and annealed at 250 � for 1 hr showing : (a) the presence recrystallized grains of 1.5 ~ 2µm in a diameter and non-recrystallized grains; and (b) elongated and equiaxed grains in non-recrystallized regions of (a).
Fig. 5 shows the duplex microstructure consisting of recrystallized grains and non-recrystallized grains in samples annealed at 250 � , as observed by Morris, et al [8].
The presence of equiaxed grains can be observed even in non-recrystallized regions, Fig. 5-b.

It was found that as the number of deformation passes increased, the coarse grains decreased, and the dynamic recrystallization fraction increased.
As shown in Fig. 2(a), after one pass of deformation, the microstructure still retained large number of coarse grains containing densely distributed lamellar LPSO phases.
Large number of low angle grain boundaries distributed inside, and the original grain boundary was jagged, surrounded by a large number of small DRX grains, showing random colors, indicating that the DRX grains had random orientation.
As the number of deformation passes increased, the DRX range increased, and the DRX grains became smaller.
In combination with Fig. 7, it can be found that the area with high KAM value usually had large number of low angle grain boundaries, which indicates that large number of dislocations accumulated in this area.

However phosphorus is easy to segregate at grain boundary and lead to cold work embrittlement[5-6].
Among grain boundaries, the coincidence site lattice(CSL) grain boundaries and misorientation between grain are known have a significant role in the recrystallization and the grain growth process and the segregation of impurity elements at grain boundaries.
The polygonal ferrites are obtained and the average grain diameters are 6~8μm.
It is evident that most of the grains are <111>//ND orientation texture.
And only small numbers of grains are <100>//ND and <110>//ND orientation texture. 50μm 50μm (a)0.035%P (b)0.056%P 50μm (c)0.079%P (d)IPF Fig.1.

A study has been carried out on the evolution of microstructure, grain boundary character and mechanical properties in a Twinning Induced Plasticity steel heavily cold rolled and subsequently annealed.The cold rolled mcrostructures showed fine lamellar boundaries with many shear bands.With progress of annealing, numerous numbers of recrystallized grains were generated.The fully recrystallized steel showed equi-axed nanocrystalline grains with a mean grain size of 400 nm that enhanced the yield strength significantly while retaining tensile ductility.
However, there is no information available about the effect of ultra grain refinement (grain size < 1 mm) on the tensile properties and their deformation behaviour.
Nanocrystalline grains are surrounded by high angle grain boundaries (HAGB) and many ∑3 annealing twin boundaries are involved in the microstructure.The mean grain size calculated including twin boundaries was 400 nm.
In summary, ultra grain refinement of the TWIP steel was examined.
In the fully recrystallized condition, equi-axed nanocrystalline grains with mean grain size of 400 nm was achieved by cold rolling and subsequent annealing.

Table 1 :ITOSample description Sample Number Of Layers Deposition Time(min) 1 1 5 2 2 10 3 3 15 4 4 20 5 1 30 6 2 60 7 3 90 8 4 120 Start Sample Preparation Indium Tin Oxide(ITO) Deposition Annealing Process(Treatment) Characterization & Analysis Aluminium (Al) Deposition Atomic Force Microscopy(AFM) Figure 1 : Process Flow Results and Discussions The AFM images are analyzed to gain information on the surface roughness and the grain size of the samples.
The grain size recorded shows highest result from sample 4 with 27x104nm2and the lowest is from sample and which records grain size value of 3.65x104nm2.
It shows that deposition time used during the process does play part in determining the grain size of the sample.
Sample 2 Sample 1 Rrms= 5.72nm Grain Size=8.15x104nm2 Rrms= 12.7nm Grain Size=15.5x 104nm2 Sample 4 Sample 3 Rrms= 24.6nm Grain Size=27x104nm2 Rrms= 18.7nm Grain Size=17.2x104nm2 Rrms= 8.34nm Grain Size=8.08x104nm2 Rrms= 43.6nm Grain Size=24.8x104nm2 Sample 6 Sample 5 Sample 8 Sample 7 Rrms= 6.41nm Grain Size=4.16x104nm2 Rrms= 10.8nm Grain Size=3.65x104nm2 Figure 2 : AFM images, surface roughness value and grain size value Conclusion As an overall conclusion of this study, the deposition time of the ITO layer does play an important parameter role in future study using the ITO material.
Deposition time do change the grain size of the material which will be an important aspect when using this material in fabrication of any device mainly in opto-electronic field where grain size do play a major role in the electrical and optical charateristics.

In the pure Cu, the nano-sized grains were formed after third cycle with an average grain size of 200nm.
Once the 200 nm grains formed, further reduction in the grain size was not observed up to the 8 ARB process cycles.
This behavior is also reported in some Al and Ti alloys [6]. 0246810 0 100 200 300 400 500 Tensile Strength (MPa) Number of cycles OFC PMC-90 02468 0 10 20 30 40 50 Elongation (%) Number of cycles OFC PMC-90 Fig. 1.
A large number of dislocations began to be observed in both alloys after the first ARB cycle.
The increase in strength with increasing number of ARB cycle is attributed to the strain hardening in the initial stage.

The results show that, the grain size is decreased with the pass number increasing, and deformation speed has no obvious effect on the microstructure.
The grid number of extruded rod was set 10,000.
It can be seen from the grain distribution profile that the grain near the corner is minimum, this simulated results show clearly that the grains were refined, however, with the increasing of passes, after 16 passes, the microstructure of the sample grain size is smaller than be pressed 8 passes, but the size of the grains are not linear decrease.
The subgrains size are larger and distribution is uniform, present a large number of dynamic recovery after large deformation.
Therefore, the grains are more thinner, as well as a large number of residual dislocations lead to inhomogeneity.

AGG, also referred to as secondary recrystallization[5], typically results in microstructures of bimodal grain sizes, containing a small number of very large grains called abnormal grains.
The point 3 has 0.9% small angle grain boundary, but point 4 has 0.6% small angle grain boundary.
Abnormal grain growth [J].
Abnormal grain growth and grain boundary faceting in a model Ni-base superalloy [J].
Influence of the primary recrystallization texture on abnormal grain growth of goss grains in grain oriented electrical steel [J].

Both processing techniques, WP and CRA, leads to grain refinement and formation of the grain-subgrain structure of submicron scale in the steels.
Quasi-equiaxed grains with banded contrast are also observed in the structure of the WP-specimens because of formation of ε-phase plates in austenitic grains.
CRA-treatment produces the ultrafine-grained structure with a grain size of 210 nm in 321-type steel (Fig. 1d).
On the side-surfaces of hydrogen-precharged and broken samples, a large number of cracks formed in the fracture zone (Fig. 3f).
On the side surfaces of the samples, there is no large number of cracks (Fig. 4c), but on the fracture surfaces, a brittle 20 μm-zone with numerous secondary brittle cracks is observed (Fig. 4d).