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The average grain size of 9~12 � is measured by specimen A, and the specimen B Journal Title and Volume Number (to be inserted by the publisher) shows 10~32 � in an average grain size.
The CuZnAl alloys have a tendency to grow large grain sizes.
By metallurgical methods, typical grain size is 0.5~2mm, and the grain size can be reduced to about 100� by grain refining addition [2].
The achieved grain size with SPS processes is found to be very fine.
Journal Title and Volume Number (to be inserted by the publisher) [3] N.

Scandium (Sc) has the ability to refine grain size of cast aluminium structure.
In addition of Sc refined grains of aluminium alloy.
For Sc content increased gradually from 0.03 to 0.70 wt.% as a result grain boundary segregation has eliminated to refine cast grain of alloys.
It also depends on number, size and density of precipitates at the moment maximum value is reached.
Addition of0.08 wt.% Sc or more leads to marked grain refinement in aluminium alloys, accompanied by a change from dendritic grain structure to an equiaxed grain morphology. 2.

To study the influence of strain path, samples of an aluminium-1%manganese alloy have been subjected to a number of strain path changes.
Fig 2(a) shows the orientation map with an overlay of the grain boundaries thick lines indicating high angle grain boundaries (HAGB), >15°, and the thin lines low angle grain boundaries (LAGB), 1-15°.
The majority of the scan is contained within one grain with a large amount of sub structure visible in the grain.
As can be seen there are a number of large second phase particles in the material which appear to have varying chemical compositions with some containing only manganese, some silicon only and some mixed.
The sub-grain sizes and aspect ratios are shown in Table 2.

The change of number, morphology and distribution of precipitation phase are the important facts to make the alloy strengthen.
It’s shown that tiny equiaxed dynamic recrystallization grains appear gradually along grain boundary after hot compression.
Compared to T5, the size of these large grains is little difference.
A large number of precipitated second-phase particles are produced after T6 heat treatment, as shown in Figure 2(b).
It shows that the number of the dimple is little and fracture morphology is mainly stonelike after T6 heat treatment, as shown in Figure 3(b).

Electropolished specimens were also examined by scanning electron microscopy using atomic number and channelling contrast in the back-scattered electron mode.
Grains in the core alloy are distinguishable by virtue of channelling contrast while the Mn-rich dispersoids appear much brighter because of their higher average atomic number and the solidified eutectic shows as a fine network of silicon flakes.
Grain growth has taken place where grain boundaries were replaced by liquid films.
Examination of a number of different areas indicated that the threshold condition for wetting corresponds to a misorientation of about 7 o.
Regions marked A show where the melt has wetted grain boundaries in the alloy and migration of these liquid films has led to grain growth in the outer layers of grains.

The plastic flow in fine-grained, polycrystalline Al2O3 takes place mainly by grain boundary sliding or grain boundary diffusion.
The segregated dopant cations change the grain boundary diffusivity and/or the grain boundary sliding itself.
Figure 6 (a) shows a HRTEM image of a grain boundary in Y 3+-doped Al2O3, together with EDS spectra taken from grain interior (b) and the grain boundary (c) using the probe size of 1nm [12].
Moreover, the presence of Y 3+ cation can be detected only from the grain boundary, but not from the grain interior.
These ideas attributed the effects to increment in the number of CSL (Coincidence Site Lattice) boundaries by the dopant [22] and to ionic sizes of the dopants [23].

During the second aging at 200°C, the specimen ARB processed by 4 cycles always showed higher hardness than the specimen ARB processed by 8 cycles, though the increase in hardness was similar, independent of the number of ARB cycle.
However, the size of the fine grains was still less than 1mm.
It is considered that misorientation at grain boundaries was increased and grains were subdivided by severe plastic deformation.
Plate or rod-like precipitates having length of several tens nanometers were also observed on grain boundaries and within the grains.
In the specimen, the ultrafine grained microstructures fabricated by the ARB process kept fine grain sizes during the two-step aging

Specifically, the Inconel 718 with refined grain size achieves 600% elongation [2,3].
The dominant microstructure and mechanical parameters of Inconel 718 alloy are Grain Size, Elongation Area, Grain Orientation and Texture Distribution, σ precipitations and secondary precipitations, Homogeneity and Stress influences [4,5].
In case of liquid cracking, Laves cluster around the liquation of grain boundary occurs liquid cracking.
Grain refinement of Inconel 718 alloy for dendrite space measurement.
McMahon, Grain boundary segregation of Boron in Inconel 718.

Introduction Twinning is an important deformation mechanism in most hcp metals because of an insufficient number of independent dislocation slip systems.
It is further seen that twinning proceeds in the studied parent grain families in accordance with the Schmid factors, i.e. the fastest in {10.0}|| grains, and slowest in {11.0}|| grains.
This post-yielding decrease in the AE activity has been previously attributed to the increasing number of dislocations and thus decreasing free length for dislocation movement as well as exhaustion of twinning activity [7].
That means that twins in one grain can lead to the nucleation of twins in neighbouring grains via an increase in the local stress at the grain boundary due to impinging on the grain boundary.
It stands to reason that a considerably higher number of twins nucleate at the onset of plasticity in the fine-grained alloy.

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.