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The initial as-cast microstructure of the alloy consists of large β grains with about grain size of 1.15-3.67 mm, as shown in Fig. 1.
With increasing temperature, a great number of micro-cracks are observed in the alpha-case (Fig. 2b).
Therefore, the micro-cracks in the alpha-case will easily propagate along β grain boundaries.
As mentioned above, for longitudinal fracture at high temperature, the crack propagation occures at the β grain boundaries.
Additionally, the alloy deformed at high deformation temperature exhibits a good ductility, whereas a large number of longitudinal cracks forms on the surface of specimens.

Metallographic studies of the structure of zirconium alloy in the initial state are shown that equiaxed grain structure with a grain size of 4 – 6 mm is formed in cross-section.
In the samples treated with N = 5 and N = 10 pulses the grain relief isn’t so obvious (Fig.2 b, c).
The grain boundaries have fuzzy contour and are not revealed presence of ultrafine lamellar structures.
As the number of pulses increases the number of craters increases too.
The structure of the irradiated and hydrogenated samples is characterized by the presence of large number of small precipitations of 3 mm.

These large grains are understood originate from the prior β grain structure present at elevated temperatures following solidification.
Upon cooling, Widmanstätten laths of α-Ti nucleate and grow into the β-Ti grains to produce the so-called ‘basket weave’ morphology.
This variation in microhardness corresponds to the observed change in microstructure and so is also linked to the greater number of thermal cycles experienced by this bottom region, giving a normalised microstructure and hence hardness.
Measurement of lattice strains in some locations proved difficult due to localised texturing of the α-Ti phase within the prior β-Ti grain boundaries.
Acknowledgements The authors would like to acknowledge the provision of beam time at the OPAL research facility operated by the Bragg Institute, ANSTO, under proposal number P2482.

The parameters controlling the value of Eb are the grain size and barrier voltage (Vgb) according to the following equation: Eb = VgbNg (1) where the Ng is the average number of grains per centimeter [8].
An accepted view is that the majority of grains are not separated by a continuous bismuth-rich phase, the bismuth are mainly located at the multiple grain junctions.
The nonlinearity in the ZnO varistor is a grain boundary phenomenon where a Schottky-like barrier to majority charge carriers (electrons) exists in the depletion layers of the adjacent grains [1].
The negative surface charge at the grain boundary interface (electron traps) is compensated by the positive charge in the depletion layer in the grain on the both sides of the interface.
As illustrating in Fig. 5, positively charged donors (Sni4+，VO2+，TaSn+, NbSn+) extending from both sides of grain boundary are compensated by negative charged acceptors (VSn4-, BiSn−, CoSn2− ) at the grain boundary interface.

Disadvantage of glass grain is their sharp-edge morphology.
These rotors have wavy protursions where individual grains abrade and their form is changed into spherical form.
Effect of grinding cycle on grain morfology Effect of grinding cycle on final form of grains was evaluated by SEM.
After grinding on this type of rotors grain edges were smoothed and form inder was completely better, but grains still create conglomerations which are unsuitable because of reduction of react surface and follow-up reduction of hydration (fig 3 and 4) Grains grinded in ball mill do not evince change of grain form in comparison with original sample pre-grinded in ball milland also evince formation of agglomerated particles of vitreous recyclate as referency pre-grindedsample (pic. 5 and 6) Useing CZ rotors appears very convenient.
For increasing pozzolanic properties it is necessary to reach the largest possible number of specific surface which would guarantee adequate reactivity.

In most of them the grain boundary effect which takes place at elevated temperatures was considered.
The number of Hasiguti maxima depends on the deformation conditions [3].
Typically, grain size in as cast Fe3Al is on the level of 0.1 mm.
Many dislocations are seen inside grains (Fig. 4c).
Microstructure of Fe-26Al (dark field): a) antiphase D03 domains in annealed at 300 °C state ([110](111)), b) size of grains after HPT deformation, c) dislocations inside grains in HPT deformed specimen.

The most important increasing is registered by the materials obtained from a smaller powder or from powder which contains all the grain size fractions.
Even though nickel diffuses slower towards the interior of iron grains, it diffuses faster at the contact border between these particles and along grain surfaces.
In the same time, these materials are characterized by a small number of pores and large dimensions compared to the materials obtained from spongy powder, which are characterized by a large number of small pores [3, 4].
This means that the fracture surfaces contain an insignificant number of interparticle necks which contain alloy elements.
After fatigue test by alternating plane bending, an increase of the cycle number to failure was observed (fig. 5).

A new approach in developing of structural materials - usage of bulk materials with an ultrafine-grained structure.
Such materials where the grain size is closer to 100 nm or less, have significantly higher strength characteristics in comparison with coarse-grained polycrystals [2, 3].
The main methods, allowing to obtain an ultrafine grain structure, are methods of severe plastic deformation (SPD).
It is also important to consider that, for SPD materials, grain size is usually the determining factor for high strength characteristics [2, 3] Therefore, to analyze the effect of grain size on strength characteristics, we will use the Hall-Petch relationship [18], which describes the dependence of growth of the yield point of a polycrystalline material with decreasing grain size.
Acknowledgments The research was carried out within the State Assignment (theme “Function”, State registration number AAAA-A19-119012990095-0).

The grain size refining was observed in Er-containing 5xxx Al-Mg alloys [8,9].
A high number density of nearly spherical Al3Er precipitates with L12 structure was formed in Al-0.4Er after aging treatment of 10 min.
Up to 90% grains has high Schmid factors (>0.40).
Phase constitution and growth manner at grain boundary in Al-Cu-Mg-Ag-Er alloy.
Grain refinement of the Al-Cu-Mg-Ag alloy with Er and Sc.

The specimen was kept in nitrogen 650°C for 14h, which could lead to the chromium depleted zone along grain boundaries of the specimen and increase its susceptibility to IGSCC [6].
Due to the chromium depleted zone along its grain boundaries, the sensitized 304 stainless steel is susceptible to IGSCC in Na2S2O3 solution [2, 6].
The intergranular SCC based on dissolution along susceptible grain boundaries is magnified 500 times (Fig. 5a), which exhibits the corrosion crack growth along grain boundaries clearly and confirms the IGSCC process.
This process won’t stop until none of the clusters change their class membership, which is able to minimize the square error for a given number of clusters [10].
Since Kovac [9] also found that the dissolution of the grain boundaries at the crack tip appeared at the same stage, it could be caused by the dissolution along susceptible grain boundaries.