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In initial state before forming, the studied alloy exhibits a mixture of lamellar and equiaxed grain structure.
The finite element simulation (FES) allows predicting the superplastic forming behavior of parts and ensuring extremely uniform thickness, avoiding a large number of trial molds, i.e. the method of “trial and error”.
The mean size of equiaxed β-grains was 0.9±0.1 μm.
At a low pressure of 0.4 the non-equiaxed β-grains were found at 0.38 strain (Fig. 5a), but the grain structure was homogeneous and insignificantly depended on the strain rate and strain in different points of the forming part.
Hydrogen Energy 35 4354–60 [21] Zhang X, Zhao Y and Zeng W 2010 Effect of hydrogen on the superplasticity of Ti40 alloy with large grains Mater.

Microstructure of such materials typically features homogeneous fine grains with certain critical maximum grain size.
The pre-condition of the effective inhibition of the SiC grain growth is either much finer grain size, or the optimum volume fraction of the additive. .
The scope of the present work included the study of the effect of introduction of TiB2 with grain size (d= 2 μm) comparable to that of SiC granules (consisting of grains with d≤ 0.1 μm).
In this case the shielding effect may be limited to the grain growth within a single granule, i.e. the expected ultimate grain growth could be limited to 4-8 μm (against possible 30-150 μm).
Development of the structural ceramics with enhanced level of mechanical (performance) parameters from ultra-fine (≤ 0.1 μm) powders sets a number of principal challenges- low relative initial density and subsequent active re-crystallization downgrade the potential advantages of the material.

On the contrary, in Ti-rich Ti-Al alloys, on increasing Ti content, the open volume of defect on grain boundary decreases, and the electron density of the grain boundary increases.
For a polycrystalline Ti-Al alloy with strong covalent bonds, the atoms in the same grain exhibit a strong order while those in grain boundary show little relaxation [25,26].
This result in the presence of large open volume defects on the grain boundaries and the increase of the value of t2.
The value of nd increase with Ti content (see table 1) implies that the electron densities on the grain boundary increases as the excess Ti atoms appearing near the grain boundary.
On the other hand, the microstructure type in Ti-rich TiAl alloys is known as the duplex structure, a2 (Ti3Al) + g (TiAl) [3], this yields new phase boundary and results in the increase of the number of the traps for positrons.

A number of researchers undertook study of this phenomenon.
A number of investigations of this phenomenon were launched.
Extension of the WRC Ferrite Number System.
Ferrite Number Prediction to 100 FN in Stainless Steel Weld Metal.
Sources of Variation in Ferrite Number Predictions vs.

The residual stresses vary across the polished surfaces and the maximum stress locates at the grain boundaries.
Daily calibration of the wave-number axis is required and was achieved by recording the Raman spectrum of silicon (one accumulation, 10s) for both static and extended modes.
The fingerprint of diamond peak at around 1332 cm-1 was predominant with the diamond grain areas of the polished surfaces, while at the grain boundaries other peaks corresponding to the transformed sp2-bonded carbon phases were also found in many spectra.
Peaks of amorphous diamond and graphite phases were more strongly pronounced on grain boundaries.
The spectra in grain and boundary regions are quite distinct.

All of the specimens observed by TEM show that at least two slip systems are operating in each grain.
The specimen having relatively lower strength and higher tensile elongations shows more than four operating slip systems in the grains.
Therefore, a proposed optimum microstructure that can achieve the improvements of both room temperature ductility and high temperature strength, is fine grained duplex (� grain + �2/� lamellar) microstructure.
While, decrease of high temperature strength would be due to the grain refinements of �2+� duplex microstructures.
It can be concluded that enough number of slip systems are operating to cause plastic deformation at relatively low stress level.

It was observed that the average grain size was greater than 3µm and a cubic perovskite structure was obtained.
XPS analysis of oxygen indicated that there existed multiform chemical state oxygen at the surface of the grain.
As can be seen that the distribution of grain size is basically uniform and the average grain size is greater than 3µm.
That is to say there exists multiform oxygen with many chemical states in the surface of the grain.
These three peaks belong to the crystal lattice oxygen of Ti-O and Sr-O, and the chemisorption of oxygen in the pores of grain surface or grain boundary [3].

The initial coarse-grained structure of the Cu-10% Zn alloy is characterized by an average grain size of 117 ± 50 μm (Fig. 1a).
The average grain size was 230 nm.
Thus, the obtained results indicate the same tendency in increase of the strength with increasing the number of passes for pure copper and copper alloy.
The increase in the number of ECAP passes increases the microhardness by almost three times.
The microhardness data obtained for pure copper and Cu-10% Zn alloy correlate well with the values of the tensile strength after a different number of ECAP passes.

Cross-sectional observations revealed that the Si diffusion layers had a two-layer structure: the top layer composed of columnar grains grown perpendicularly to the substrate surface and a transition layer with equiaxed grains was close to the substrate.
The top layer composed of columnar grains grown perpendicularly to the substrate surface and a transition layer with equiaxed grains was close to the substrate.
As a result, columnar crystals normally grew to the surface from a relatively small number of crystallization centers.
The different growth rates of the columnar grains resulted in unsmooth surface in the columnar grain layer.
The top layer composed of columnar grains grown perpendicularly to the substrate surface and a transition layer with equiaxed grains was close to the substrate.

AWJ machining requires a lot of investment, and processing efficiency is not suited to creating large numbers of small holes[1].
Previous research into other processing methods has shown that blasting can be used to effectively create large numbers of small holes.
The diameter of holes and the number of passes by each media are shown in Figure 7 as examples.
The abrasive grains were filmed immediately before colliding with the test piece.
Abrasive grain speed was calculated based on the moving images taken.