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The reason for the development of IGC is the chemical heterogeneity between the border zones and the grain volume.
The intergranular corrosion (IGC) is characterized by selective destruction along the boundaries of metal crystallites (grains).
The occurrence of stresses as a result of the formation of new phases along the grain boundaries. 3.
In this way, the ferritic grains are hardened much more strongly than pearlite grains.
In this case, ferritic grains become anodes, and pearlite grains become cathodes.

High strain rate superplasticity has been realised at room temperature for the first time with a ultra fine grained Zn-22wt%Al alloy.
In this study, a seismic damper was designed with a Ultra fine grained Zn-Al alloy.
In Photo. 1 with low magnification, α-grains with the size of about 1 μm (Al particles) and β-grains (Zn particles) exist together.
β-grains are Ultra fine grained as predicted theoretically. 2.
(1) By applying TMCP to Zn-Al alloy, a massive ultra fine grained material was manufactured successfully.

Wear resistance was tested at equipment type MLS-225, under conditions of: diameter of rubber wheel 174mm~178mm, shore hardness 60, rotational speed 240 r/min, number of turns 6000, sand/water mass ratio 1.5, load 100N.
For heat-treatment I in Fig.1 a) and d), more undissolved carbides are observed and dispersed like block or diamond, and less in grain boundary.
This microstructure contributes to preferable properties, yet the coarse grain size acts the opposite.
In this case, heating at low, medium, and high temperature and holding for a settled time, brings several strengthening effect to Mn steel, such as grain refine strengthening, solution strengthening and dispersion strengthening.
Final microstructure is fine carbides dispersing in fine austenite, but carbides tend to precipitate along grain boundary in reticular type, reducing properties.

At the same time, grain boundary migrated across the pore, and large numbers of pore disappeared at the place swept by grain boundaries .That resulted in the grain size increasing.
The number of closed pore increased largely, pore shape approached spherical and shrank.
The size and shape change of phase grain suggested the atomic diffusion and migration of grain boundary.
Comparison of four photos, it can be found that with the increase of sintering temperature and heat preservation time, more complete grain appeared, and grain merged and grew up.
Combined with XRD analysis above, iron-nickel solid solution can only appeared in the vicinity of grain boundary.

Table 4 – Contamination of steels with non-metallic inclusions (maximum/average) Steel Type of non-metallic inclusions Sulfides Point oxides Stringer oxides Brittle silicates Deformable silicates AVTs40Kh 1.50/1.36 0.50/0.50 3.00/1.58 4.00/1.58 3.00/2.93 AVTs40KhGNM 3.00/2.50 0.50/0.50 2.00/2.50 0/0 3.00/2.25 The presence of bismuth refines austenite grain even in the melts where aluminium content is critical and cannot provide austenite grain size of ASTM number 6 (Table 5).
Table 5 – Content of bismuth and retained aluminium and austenite grain size Steel [Bi], % [Al], % ASTM grain size number AVTs40Kh 0.11 0.005 6–7 AVTs40KhGNM 0.09 0.015 7 Surface quality of 80 mm square billets presented in Table 6 satisfied technical requirements.
Criteria for estimating machinability were relative durability (the number of machined parts resulting in 0.1 mm flank wear of tool) characterizing wear intensity, surface roughness of the workpiece (at the same degree of tool dulling), and chip breakage.
Austenite grain size was not greater than ASTM number 6.
Austenite grain is refined with increasing bismuth content. 4.

In fact, doped barium zirconate shows highly refractory nature, which generates small grain sizes and a large total grain-boundary area[7].
Small grain sizes facilitate densification at relatively low temperature by contrast it introduces a larger number of grain-boundaries.
High temperature sintering promotes grain-growth which indeed reduces the total grain-boundary area.
However according to Babilo & Haile[7], excess Zn supposed to be incorporated on the Zr-site of the grain-boundary regions, leads to an increased number of vacant Ba and O sites, which in turn promotes an increase in grain-boundary mobility, grain growth, and densification.
This may restrict the dopant (Yb3+) to form a sufficient number of vacant oxygen sites.

Journal Title and Volume Number (to be inserted by the publisher) 3 macroscopic response.
Thus it appears that a back stress is generated in those grains in which twinning is activated, and that load shed by these grains is taken up by grains in which no twinning takes place.
Journal Title and Volume Number (to be inserted by the publisher) 5 Cyclic Loading.
The legend refers to the cycle number.
This is consistent with the intensity variation expected from grain rotation due to basal slip.

The term n indicates the number of octahedral layers present in the pervoskite slab.
The plate like grains are randomly oriented and grain growth is in the ab plane [14].
Complex impedance plot is resolve into two semicircles which are indicates the grain and grain boundary contribution.
The high frequency semicircles are represents grain property of the material and lower frequency side semicircle represents grain boundary contribution.
The resistance and capacitance of grain, grain boundary and electrodes are mentioned in Fig 6.

Fig.2 shows the plots of plastic strain amplitude vs. number of reversals to failure on bi-logarithmic coordinate.
The grains aggregate among the lamellar colonies.
But at 650°C, small amount of lamellae begin to coarsen by the dissolution of α2 phase, and some γ grains grow up by incorporation of small grains (black arrow in Fig.3c).
These multiplied dislocations were generated at γ/α2 interface or γ grain boundary, and then moved ahead under the low shear stress, finally terminated at another side of γ/γ interface or γ grain boundary.
The plastic strain amplitude vs. number of reversals to failure fits well with Coffin-Manson's liner relationship

Regrettably the number of works in this field is still very small.
Under the term of "surface" both external surfaces (free surfaces) and internal surfaces (grain boundaries, dislocations, etc.) are considered.
A survey on the effect of grain boundary diffusion on formation of oxide layers on metals is presented by Smeltzer.
Available, experimental data on grain boundary and dislocation diffusion in alumina are reviewed by E.G.
The effect of the surface and grain boundaries on the sintering and densification of zinc oxide is discussed by Kobayashi.