Search results

It was found that a surface of titanium samples tested on the vibratory stand was covered by very large number of microcracks which in a later stage of the research leads to the erosion of the material.
The average grain size was approximately 20 µm (Fig. 3).
Results of the EBSD evaluation of the Ti99.7 titanium structure: a) the inverse pole figure map, b) the basic triangle, c) the inverse pole figure for ND, d) area fraction distribution of the grain size, e) number fraction distribution of the grain size The Ti99.7 titanium exhibited a good cavitational resistance upon testing on the vibration stand.
In the further step, an effect of uplifting and collapsing of titanium single grains took place leading to a detachment of whole grains or their agglomerates (Fig. 5c-d).
The cavitational destruction of Ti99.7 samples tested at two different stands begins at grain boundaries of the a phase and slowly grows toward an interior of grains leading to a surface damage.

The sheet metal is modelled as a grain aggregate, each grain having its own flow stress.
In particular the sheet metal is modelled as a grain aggregate, each grain having its own flow stress.
- At 0.8Uf, the number of shear bands stabilized and a plateau value for the surface undulations was reached
The total number of elements was 16,404 with 16,147 in the part undergoing large deformation.
Grain mechanical behaviour.

Microstructure evolution and information (e.g., grain size, grain shape, misorientation angle distribution, grain size distribution) was characterized and analyzed by optical microscopy (OM), H800 TEM and EBSD equipment.
After annealing 3 s at 673 K, the deformed microstructures just start to recrystallize (Fig. 3), some fine grains could be seen around the boundary of deformation bands and the number of recrystallized grains increased with annealing time.
After 10 s, deformed AA7075 Al alloy is fully recrystallized with fine-elongated grains, and the grain size and shape are unchanged with extending times, as shown in Fig. 3.
The recrystallized AA7075 Al alloy exhibits a fairly steady fine-grained structures with ~10 μm mean grain size with different recrystallizing and solutionizing processes.
The Erichsen test results of present AA 7075 Al alloy with different grain sizes (6-25 μm) acquired by different recrystallizing schedule show the good formability is acquired with ~10 μm mean grain size, which gives an Erichsen value of 7.34 mm, and neither larger nor finer grain was in favor of formability.

Currently, a large number of efforts have been done to investigate the FSW of aluminum alloys.
The HAZ remains the same grain structure as the BM and the grain has a certain extent of coarsening with respect to the BM as is shown in Fig. 1(e) &Fig. 1(b).
The TMAZ experienced plastic deformation with a certain extent of strain hardening effect and the number of MgZn2 increases while the number of AlCuMg decreases.
In the HAZ, the number of the MgZn2 increases and the number of the AlCuMg decrease further, respectively.
When the rotational speed is 800r/min, the number of MgZn2 decreases while the number of AlCuMg increases, as is shown in Fig. 7 (b).

Different grain sizes could be achieved by choosing different temperatures.
It means that the formability would improve if the grain size increases.
However, the large grain size also decreases the plastic strain ratio.
It implies that the distribution and the direction of grain size are hard to be controlled when the grain size increases.
The extent of the changing of material properties is affected by the number of grain in the cross section.

Microstructural observations revealed that this alloy consisted of fine equiaxed grains and a large number of RE-containing precipitates.
The grain size was fairly small in comparison with the RE-free Mg alloys, such as AZ31 and AM30 [4,7].
It was reported that grain size had a significant effect on the tendency of twinning since the energy required to form twin interfaces was particularly high in the fine-grained Mg alloy [8].
Fig. 4(a) shows the evolution of stress amplitudes as a function of the number of cycles at different applied strain amplitudes on a semi-log scale.
Jiang, Grain refining mechanism in Mg-9Gd-4Y alloys by zirconium, Mater.

According to the TEM observations, the DRX microstructure can be categorized into three kinds: grains with low dislocation density, which are DRX nucleations; grains with low dislocation density around the grain boundary and high dislocation density in its interior which means that grains with dislocation density gradient and which are DRX grains in growth; grains with high dislocation density, which are fully work-hardened DRX grains.
The deformation bands are produced in the grain interior, and the small nucleation can be found around the deformed grain boundaries although they are few in number, which means the beginning of DRX.
With increasing deformation, the fine DRX grains increase and displace the coarse grains.
When the strain was 0.6(Fig.2 d), the DRX grains almost displaced the coarse grains fully.
The DRX microstructure can be categorized into three kinds: grains with low dislocation density, which are DRX nucleation; grains with low dislocation density around the grain boundary and high dislocation density in its interior which means that grains with dislocation density gradient and which are DRX grains in growth; grains with high dislocation density, which are fully work-hardened DRX grains.

The results of the XRD analysis showed that both the 5- and 10-coated layers are polycrystalline BaTiO3 with differences in terms of diffraction intensity, due to the number of layers.
The number of layers of 5 and 10 have thickness of 2.927nm and 4.456nm RMS.
Figure 3 (a) and (b) show the same layers but on a 3-D perspective where the layer grain growth is seen to produce rougher terrain due to the bigger and more uneven grains in the 10 layer film.
The higher 80,000x magnification, for the 5 layer film, shows grains and the grain boundaries, with some voids between the boundaries.
Surface of BaTiO3 for 10 layer coating CONCLUSION Multilayer BaTiO3 films have shown increasing grain size in proportion to numbers of layers, as verified via both AFM and SEM result.

The purpose of the second treatment was a maximal enlargement of grains.
The sizes of the grains vary between 70 and 120m (Fig. 1, 2).
About 10000 more cycles are added to the total number of cycles providing fracture.
The increase in number of cycles leads to the formation of microcrack at grain boundary, and it propagates along grain boundaries (Fig.2), so that, along straight boundaries it propagates without apparent deviations.
The former austenite grain is etched (treatment N1).

By this mechanism, the internal structure of a high percentage of deformed ND fibre grains could be influenced: the resultant fragmented nature of those grains has been noted in a number of previous works on cold and warm rolled IF and low carbon grades [5,6,7,3].
ND fibre orientation is more commonly associated with grain boundary nucleation [8,9,10,11] However, it has been shown by several authors that the fragmentation of deformed ND fibre grains, (via the formation of in-grain shear bands, deformation bands,…) promotes the nucleation of ND fibre grains in grain interiors [12,5,3,13].
The IQ map of the annealed ULC steel show that during the first stages of recrystallization, a large number of crystallites of small sizes generate in the deformed high stored energy {111} zones, within a high angle boundary network configuration.
During annealing a large number of crystallites of small sizes generate in those zones, within a high angle boundary network configuration.
Conf. on Rex. and Grain Growth, Trans.