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So no matter how strong the electron beam was, it only irradiated 1-2 crystal grains.
Due to big residual stress around, the dislocation pinned and crossed crystal grains, and crack produced segregation for the exist of zirconia grains which consumed a part of fracture energy.
Grain-boundary sliding is another one of the deformations as shown in Fig.4(b).
In Fig.6 phase corresponds to a number of peaks.
According to qualitative investigation and indicators, the ground surface of Al2O3-ZrO2(n) is composed of α-Al2O3 with diffraction angles of 35° and 30°, t-ZrO2 and a small number of m-ZrO2 with diffraction angle of 28°.

This paper generalizes an earlier proposal [4-10] to explain superplasticity in terms of a single rate controlling mechanism, viz., grain boundary sliding (GBS) that develops to a mesoscopic scale (defined to be of the order of a grain diameter or more), regardless of the material class and grain size range.
Grain boundary dislocations are unstable [11] and are not a part of a description of general high-angle boundaries.
Detailed calculation [6,7] has resulted in an expression for τ0 given in Eq. 1, where G is the shear modulus, L the mean grain size, N the number of grain boundaries that form the plane interface (its temperature and grain size dependence has also been determined [5-8]), γB the specific grain boundary energy and αf is a form factor ~ 1.0.
As the grain boundary width is ~ 0.50 nm [32], it follows that this changeover would take place at 2.45 nm.
Conclusions Grain boundary sliding that develops to mesoscopic scale is proposed as the common rate controlling process for superplasticity in different classes of materials of grain size from μm- to nm- range.

A wide variety of grain sizes and grain boundary distributions can be obtained by DRX directly during plastic working.
The new DRX grains appear only near initial grain boundaries.
New fine grains comprise a necklace structure forming at serrated initial grain boundaries; core areas of initial grains remain unrecrystallized.
However, new fine grains scarcely developed at serrated grain boundaries.
The numbers in schematic drawing indicate the boundary misorientations in degrees.

The results indicated that there existed large amount of nano/micro-scale grains produced by sputtering and impacting of the melting Al-Si jet.
Meanwhile, some sub-micron grains at the interface were observed, and selected area electron diffraction (SAED) pattern represented typical Face-Centered Cubic (FCC) features of Aluminium alloy.
The grains in nano phase area were basically isometric crystalline, its size were smaller than 100nm.
The existence of metal stable nano-scale grains in Al-Si coating would evidently improve the interface activity and promote formation of metallurgical bonding.
Analysis of deposition behavior of Al-Si particle coated on ZM5 magnesium alloy elucidated that there existed a majority of ellipsoidal sub-micron scale grains at the edge of flattening particles.

Then the alloy was annealed in order to obtain samples of a given grain size.
An average grain size is about 100 nm (Fig. 1).
At higher magnifications one could see that the alloy was not fully recrystallized and there was quite a number of defects inside the grains.
Also quite a number of low angle boundaries was found inside some grains.
The average grain size was 100 nm.

The rate-limiting step of this process is supposed to be boundary diffusion of solute along grain boundaries.
Moreover, beside DP and DC, GB motion is observed to be involved also in many other solid state reactions such as diffusion induced grain boundary motion (DIGM), diffusion induced recrystallisation (DIR), as well as grain growth [2].
Rapid evolution and grain boundary migration for dominating bulk diffusivities: =1 and =0.
The numbers “n” mentioned on each picture indicate the time sequence during the run such that: t= n*ifreq*Δt, where Δt =0.02 (in units of the phase-field relaxation time), and ifreq denotes the frequency of picture “emission” and varies from one run to the other (ifreq=2.104 generally).
Indeed, the grain boundary mobility also comes into play: a change in this quantity changes the geometry of the grain boundary and thus the “drag force” exerted by the attached grain boundary on the precipitate.

The effect of grains boundaries self-orientation caused by grains deformation was evaluated using stereology.
But the orientation is not the same as deformation and so a correlation between the grain deformation and grain orientation was used.
In an undeformed state, the structure is isotropic, the grains have isometric dimension and grain boundaries are not oriented.
From the specific number (number to unit of length) of parallel test lines intersections with grain boundaries (PL)P and perpendicular lines ones (PL)O, the total specific surface area (SV)TOT of grains and the planar oriented part of specific surface area (SV)OR of grains were estimated.
From measured grain boundary orientation which is proportional to grain boundaries deformation degree the local plastic deformation was estimated.

Figure 3 The number of recrystallized grains in Specimen A1 and A2.
Fig.3 shows the numbers of RGs formed in Specimens A1 and A2 [3,7].
In Specimen A1, the number of RGs in the a-b-c-d plane was forty-two, which was originally in the state of the surface at both deformation and annealing.
However, the number of RGs in the interiors decreased with decreasing the thickness (or being far from the surface).
But the existing of grain boundaries induced more nucleation and growth of RGs in/on the grain boundaries in the inside, because vacancies pass more easily through grain boundaries than through/in grains.

Therefore the used definition “the dynamic superplasticity” reflects consecutive change of states which happens in material with initial varying grain size structure under the changing temperature-rate conditions: initial varying grain size → equiaxed fine-grained structure (4…7 microns) formed in the temperature-rate conditions of superplasticity → coarse-grained at further increase in strain rate.
Formation of fine-grained structure and its dependence on temperature and strain rate in the range of phase transitions, create conditions for realization of the mechanism of grain boundary slipping, characteristic for superplasticity.
Statement of the specified task is based on a large number of the experimental data generalized in [1] and relating to alloys as: AMg5 (AlMg5, 5056), 1561, D18T (2117), 1980, B95 (AlZnMgCu1.5, 7075), AK4 (2618), AK6 (AlCuMg0.5, 2117), AK8 (AlCuSiMn 2014).
Valiev, Grain Boundaries and Properties of Metals, Metallurgiya, Moscow, 1987
Lyashenko, A model of grain boundary sliding during deformation, Technical Physics Letters. 38 (11) (2012) 972–974

Fatigue Behaviour in Fine Grained Aluminium Alloys L.J.
A fine, predominantly equiaxed grain structure withtypical grain widths of 3-5µm was seen.
A moderate grain size of ~5-20µm was seen (equivalent to the through-thickness grain dimensions in conventional DC cast plate and sheet products) with a <101> fibre texture being identified. 5091 is an Al-Mg-Li mechanically alloyed material [6] offering an ultra-fine-grained microstructure, with relatively equi-axed grains of less than 1µm size, stabilized by dispersions of 20-50 nm Al2O3 and Al4C.
A number of rogue 2-50µm grains were also seen however, up to ~ 25% of the material bulk [7].
In the first instance it is evident that growth rates do not scale simply with grain dimensions, as SC2 has the coarsest grain size amongst the present fine-grained Al alloys.