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Discontinuous yielding phenomenon has been observed in a large number of beta titanium alloys [5,6].
A large number of mobile dislocations increased suddenly leading to a sudden stress drop.
The initial equiaxed B2 grains elongated, the dynamic recrystallization grains can not be found.
Grain boundaries are straight and deformation bands are formed vertically to the compression direction indicated by arrows.
A lot of deformation bands were observed, dynamic recrystallization grains were not observed in the microstructure.

Fig. 1 Fracture area and direction of loading – sample A a Crack spreading along the carbide rows b Crack spreading preferably along the boundaries of primary carbides - detail Fig. 2 Microstructure with secondary cracks (etched in 3% Nital) - sample A From the microscopic analysis (Fig. 2), it is evident that a large number of primary eutectic carbides are present in the microstructure forming a relatively continuous mesh around the primary grain of the steel.
These carbides are up to five times larger than the prior austenitic grain.
According to ASTM scale, the grain size corresponds to grade 10 (real grain size dm » 8 mm).
Number of pores with different dimensions was observed.
Prior austenite grain size, depth of hardened layer, surface and core hardness (Fig. 6) was in accordance with documentation.

This results in a reduction of short circuits by debris contamination and also reduces the number of open circuits by gap control system in reaction to the short circuits.
All these give rise to higher number of successful discharges.
During the EDM /USM process, USM will stir up abrasive grains to strike the workpiece with high velocity and acceleration and cause micro-cracks beneath the machined surface to remove the material.
The working medium is the mixture of water with B4C grains, some reactions showing as eq.(1),(2),(3) happen.
One reason is that grains strike the surface with high frequency to reduce the depth of crater formed by every discharging.

The more the number of passes employed, the more uniform strain distribution obtained.
However, as the contact area with air and rolls increase while the number of the passes increases, the heat generated from plastic work is not enough to maintain the temperature at the top surface, which causes the surface temperature reduced rapidly.
It is found that after 24 passes, the subgrains are homogenised with a grain size of 25 mm.
It is well known that hot working helps decrease chemical inhomogeneities in cast structures, refine coarse cast grains and homogenise the grain distribution across thickness [10].
Longer time at high temperatures allows more grain growth [11].

Additives such as Ni have been shown to play an important role in promoting densification [3], and cause the precipitation of a second phase on the grain boundary.
Experimental Commercially available powders TiN and TiB2 bought from Nano Technology Company of Shanghai Chao Wei were used as the raw materials, the average grain size and purity of TiN are 1μm and 99.8%, the average grain size and the purity of TiB2 powder are 700nm and 99.8% respectively.
Comparing with Fig.6 (b) and Fig.6 (a) grain size increases and density is improved at the same time,which is helpful to improve the flexural strength of the composite.
Moderate grain size is more benefical for the flexural strength.
Fig.6 (c) shows that the grain size is coarse due to the fast crystal growth at high sintering temperature, which induces excessive grain growth and resultant microcracksthat are harmful for the mechanical properties [4].

Moreover, with increasing number of varistor is being used for low-voltage applications such as in large-scale integrated circuit and semiconductor electronics, SrTiO3-based varistor ceramics have been shown to be potentially useful as excellent varistor materials.
More recently, although there have been a number of studies dealing with the electrical properties as well as microstructures and varistor characteristics in SrTiO3 and (Ba, Sr)TiO3 ceramics[4,5,6].
This can be explained as follows: acceptor dopants such as Mn may segregate to the grain boundaries to achieve ideal electrical properties.
As it is indicated in Fig.2, the grain size increases greatly with an increase in the amount of MnCO3 added.
From these results it may be reasonable to conclude that the increase in the relative dielectric constant εr and the decrease of dielectric loss tanδof the materials with increasing Mn content are attributed to an increase in grain size to some extent, which obeys the approximately relation: εr=( dgr/ dgb) εgb (5) where dgr and dgb is the grain size and grain-boundary layer thickness respectively, and εgb is the effective dielectric constant of grain boundary.

The numerical model developed is useful to have integrated results as input for the optimization algorithm in order to drastically reduce the number of experimental tests needed.
An initial population is set containing a predefined number of solutions (individuals).
Aluminum alloys are widely employed as structural materials owing to a number of advantages including good ductility and formability, high strength to density ratio, and elevated corrosion resistance, together with good vibration-damping characteristics and stiffness, which make them suitable for a number of weight-critical structural applications. [7] It is used in a number of important engineering applications that span from low to room temperature such as: transport applications, including marine, automotive and aviation applications, due to their high strength-to-density ratio.
The objective function is defined in Equation 1 as: Uv,n,f=CRRa-Ra'Ra+CPP-P'P+CMMR'-MRMR'+CHHV'-HVHV'+CDD-D'D+CTT-T'T (1) where Ra is the surface roughness, P is the cutting power, MR is the material removal rate, HV is the surface hardness, D is the surface grain size, T is the cutting edge radius variation.
HV’ is the minimum hardness value set to be equal to the bulk material, D’ is the maximum grain size fixed at the value of the virgin material, finally, T’ is the tool wear corresponding to a completely worn tool.

The saltation grains traveled by making long jumps and the reptating grains move in hopping manner over a much smaller distance[8].
The Saltation Transportation Model of Sand Grains[4,5] Fig. 1 Saltation track of typical sand grains Fig.1 shows the movement track of the sand grains.
It can be assumed that the sand grains jumped at the same time with its track which is an inclined on one side parabola orbit and the sand grains with average mass and average diameter.
Sand grains will be rose up by the wind with average angle (around 35-45 degrees), it can be also assumed that the sand grains moved along the parabola orbit and the sand grains fall back to the ground with the angle (around 10-15 degrees).
is base value of jumping distance of sand grains, is wind velocity, is sand grains critical wind velocity for jumping, and are the average mass and diameter of the sand grains.

Since a few ribbon grains extend up to 10 µm along the RD, considerably larger aspect ratios () ~4 (±2) were recorded along with a small number of ~0.1–0.2 µm (sub)grains with ~1.5–2.
The large (sub)grains appear to be inherited from prior ECAP processing.
After 300 s and for up to 1 h, discontinuous coarsening produces ~100-150 µm abnormally grown grains and ~4.5 µm uniformly coarsened matrix grains (Fig. 3(c)).
Here, the heterogeneous dispersion of abnormal grains was also confirmed by EBSD over a scan area of ~7 × 0.2 mm2.
After 1 hr ~80% of the map area is covered by the abnormally large grains (~38) as they consumed a significant fraction of surrounding matrix grains.

More than 50 percent of the tool failure is due to the unstuck and rupture of the interface between the grains.
Based on Mori-Tanaka theory, and the nano-sized grains distribute uniformly in the materials (in Fig.2).
Table 2 Mechanical property of the composites tool materials Number ZrO2 content (%) Hardness (GPa) Bending strength (Mpa) Fracture toughness (MPa.m 1/2) a 3 18 500 6.9 b 8 18.6 784 8.8 c 13 18.7 821 9.1 d 18 18.2 722 9.2 Microstructure of the tool materials are shown in Fig.3.
Meanwhile, the interfaces of the grains are dense.
The two morphologies are depended to the strength of the grain interfaces.