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They also have several weaknesses, the main one being their propensity to form a coarse-grain eutectic (α+β) [1].
The coarse-grained microstructure of alloys lowers their mechanical properties.
The resulting small-grained eutectic increases the plasticity as well as the strength of the resulting alloys, which is a characteristic feature of silumins [3,4,5].
The above sample was also characterized by a finer-grained α-phase.
The β-phase was characterized by a finer-grained eutectic, and α-phase grains assumed a round shape.

It is expected that extensive occurrence of grain-boundary sliding caused such superplasticity in the AZ31 alloy.
The hexagonal-unit cell of the matrix single crystal rotates by the deformation (Fig.4) .In the Crystal A, relatively large crystal rotation took place, which brought about complex slip morphology on the surface by increasing the number of the activated slip systems accompanied by twinning.
The formed grain boundaries by DRX caused cracking to shorten the elongation.
This delays the occurrence of DRX and, therefore, grain-boundary fracture to loss the ductility.
The formed grain boundaries became initiation of cracks to lower the ductility during the deformation.

The incorporation of ceramic particles can stabilize a fine matrix grain size, which leads to higher toughness and strength.
Their research results show that the introduction of Ti2AlC in TiAl intermetallic can prevent the movement of the grain boundaries, restrain the growth of grains, and improve its mechanical properties obviously.
The sample without C doping (Fig.2 (a)) is very coarse grain sized.
While the sample with 5 % in situ formed Ti2AlC possesses a duplex structure with fine grain size.
(2) With increasing C content in starting materials, the matrix grain size was reduced and dispersed more uniformly.

If the upsetting dies (number 3) illustrated in Fig. 4 are substituted for a portion of the long tube billet itself under room temperature, the tube structure with a nozzle for a long tube can also probably be produced by RUE process as long as the partial region (number 1 in Fig. 4) where hot plastic deformation will be performed is heated to forging temperature.
The model of grain growth could be described by formula (7), and grain size after growing could be determined by initial grain size , time t and absolute temperature T[21]. . (7) where is the grain size after growing, is the grain size after complete dynamic recrystallization is finished.
As for 316LN, the major recrystallization is dynamic recrystallization, which plays an important role on grains refinement.
Thus, one of important goals to perform plastic deformation is to achieve grains refinement.
Apparently, the nozzle formed by RUE process could get refined grains based on the mechanism of recrystallization.

Introduction Severe plastic deformation (SPD) has been known to be one of the effective methods to obtain ultrafine-grained (UFG) materials [1-3].
The ECAP process can apply a large shear strain to materials through a specially designed die having two equally sized channels connected at a finite angle, so a remarkable grain refinement occurs by repeated shear deformation.
The mean equivalent area particle diameter of the number of ECAP passes is presented in Fig. 2.
In Fig. 3, the mean volume fraction of Al3Ti particles as a function of the number of ECAP passes by route A is shown.
of the number of passes through the die (route A).

A number of pulled out grains and/or micropores can be seen in this figure.
At the end of region 2, the number of fibres behind the crack tip increased considerably.
Therefore, the number of bridged fibres dropped sharply.
d) Fibre Pull-Out/Grain Pull-Out.
This is shown in Figure 5, where pulled out fibres can be seen with large numbers of HAp grains still attached.

However, if the real annealing at effective temperature leads to the grain growth, SPD leads to strong grain refinement.
With an increasing number of rotations, the lattice parameter of Sample 1 decreased and that of Sample 2 increased.
Let us compare the HPT-driven mass transfer with possible input of grain boundary diffusion.
This area includes several (Al) grains and many (Al) GBs.
In case of decomposition of Cu–Ni alloys [15] the average grain size after HPT is about 100 nm.

Introduction In the case of dispersion strengthened materials the failure initiation is influenced by number of factors, for example morphology (size, shape, distribution of dispersion particles and size and morphology of matrix grains, etc.), volume fraction of dispersion particles, distribution and interaction of particles with the matrix as well as loading conditions of the composite.
The mean grain sizes of MMCs decreased with the increasing weight percentages of Al2O3 particles [22-24], the nano-particles acted as hard restrictive obstacles against grain growth.
Langdon, The process of grain refinement in equal-channel angular pressing, Acta Mater. 46, 9 (1998) 3317-3331
[9] RZ Valiev, TG Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog.
Lin, Grain refinement of AM60/Al2O3p magnesium metal matrix composites processed by ECAE, Kovove Mater. 51, 6 (2013) 357 – 366

Additionally, the fluidity is important to control the number of gas bubbles in specimen according to the microstructure analysis. 1.
The effect of ZnO on reducing refractoriness is the worst among them, and the value stays the same with the content of ZnO above 6wt%. 3.2 High-temperature fluidity Fig. 2 High-temperature fluidity of vitrified bond with Li2O, K2O and ZnO additions The fluidity makes a great difference on the combination state of CBN grains and vitrified bond [11].
Herman, Glass and glass-ceramic binder obtained from waste material for binding alundum abrasive grains into grinding wheels, Ceram.
Karpiñski, Effect of glass-crystalline and amorphous binder application to abrasive tools made of microcrystalline alumina grains type SG, Wear, 209(1997) 213-218
Procyk, Influence of crystallization of the glasses zincoborosilicatlead system on wettability of cbn grains, Proc.

The partial recrystallized grains occur and they are elongated along the deformation direction.
The precipitated phases continuously distribute in the re-melting grain boundary.
In addition, some of large particles randomly distribute in the grain and/or the grain boundaries, and they are mainly the strengthening phase and the impurity phase.
Therefore, the number of the nucleation during aging is reduced, which will coarsen the precipitates and weaken the strengthening effect of aging.
On the contrary, the elongation rate is not mainly determined by the number of the nucleation during the aging process, so there is a small change.