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The number of grains containing in-grain shear bands, increased with decreasing deformation temperature; after deformation at 600 °C or 550 °C bands were observed in every grain but at 750 °C or above, shear banding was detected only in some grains.
In-grain shear bands appeared to be intense in the g-fibre grains, but also grains with other orientations contained in-grain shear bands.
The highest number of nuclei formed at the original grain boundaries – especially at triple junctions, although nucleation also took place readily in the in-grain shear bands.
Reheating to 950 °C and immediate cooling was sufficient to produce large number of small recrystallized grains.
Evidently however, the number of grains containing in-grain shear bands decreased with increasing deformation temperature.

The cold working process multiplied the dislocations and led to the grain fragmentation.
The cold working process multiplies the number of dislocations in pc metal, which are arranged the network with a low angle misoriented cells within coarse grain interior at the center of the specimen where the moderate equivalent shear strain εv is .
The succeeding strains progress the fragmentation of grains.
The saturation of grain refinement is achieved by an equivalent strain of for nickel [1].
It is noteworthy that there are large angle grain boundaries for the uf microstructure.

Introduction Severe plastic deformation (SPD) is regularly applied to achieve ultrafine-grained (UFG) metals and alloys that have grain sizes in the submicrometer and nanometer ranges [1,2].
Fig. 3: The volume fraction of texture components versus number of turns.
Then, the texture is fairly isotropic after processing by HPT through a total number of 20 turns.
Superplastic flow is observed in the samples processed by HPT through total numbers of more than 5 turns.
Langdon, Twenty-five years of ultrafine-grained materials: Achieving exceptional properties through grain refinement, Acta Mater. 61 (2013) 7035-7059

INTRODUCTION Grain refinement induced by severe plastic deformation (SPD) in metals is a well-known phenomenon.
In this study has been used ECAP method for synthesizing ultrafine grained materials, the mechanical strength of which is remarkably elevated.
ECAP is a very popular method for modifying microstructure in producing ultrafine grained (UFG) materials and nanomaterials.
The mechanism of grain size reducing based on SPD has been extensively investigated for those materials, such as Fe, Cu and Al, coarse grain structures are refined by various dislocation activities [1-6].
It was determined that for a number of two passes in an ECAP die with intersecting channels angle φ = 90° and a corner angle ψ = 20°, an increasing in ultimate tensile strength (σ UTS) up to approx. 100 and 200%.

However, their applications are limited by a number of undesirable attributes.
A number of techniques have been developed to realize such a microstructure [3].
When cast near the liquidus, the grains became rosette or rosette-like.
The microstructure cast at 720°C was considerably different from that of AZ91D because of heterogeneous nucleation due to Zr, and consisted of irregular cellular or rosette grains with grain sizes of ~40-70 µm.
When cast at the liquidus temperature (629°C), the primary grains were all highly globular; most grains were 10-20 µm in size.

It is necessary to study the reservoir heterogeneity of the number 2 of shanxi Formation in this block for concerning the unfavourable extraction condition.
The study indicate that reservoir plane heterogeneity of the number 2 of shanxi Formation in study area presents the medium to slightly strong characteristics in general.
The shanxi Formation can be classified to number 1 and number 2 basing on lithology characteristics.
The main sandtone types are medium-to coarse-grained containing gravel or seriate grain rock-fragment sandstone, lithic quartz sandstone and quartz sandstone.
The sedimentary system of the member 2 of the shanxi Formation is a marine braided river delta whose reservoir is mainly distributary channel sand body and the reservoir space is a combination of holes between grains, dissolved pores and micro cracks.

Cuza nr.13, Craiova, Romania, 200585, avictorczh@gmail.com, b stefan_iuly@yahoo.com Keywords: ferrite, ceramic materials, microwave heating, thermal-gravimetric analysis Abstract In this work there are presented the results of experimental researches which had the goal to establish the thermal effect of BaCO3 and α- Fe2O3 homogeneity mixture heated in microwave, used to processing barium ferrite W type by pyrosynthesis.There was used thermal-gravimetric analysis with a derivatograph reordered for microwave heating of samples containing iron oxides with different grain size.Experimental results emphasized that the microwave heating comparatively with resistor heating, lead to a lower synthesis temperature of hexaferrite of about 150 0 C , using oxides with grain size suitable to SBET= (7-10) m2/g.
They are used too in automotive industry and airspace vehicles.The hard ceramic materials are used in a large domains number .To produce these materials at industrial level the ceramic method [2,3].Other methods like the chemical methods as coprecipitation [1], SHS (self-propagating high temperature synthesis), hydrothermal method synthesis from aqueous sol-gel auto-combustion are used in laboratory because the need to use expensive raw materials and low productivity.
Material Purity[%] SBET [m2/g] Grain size range [μm] Average grain size Grain shape Density [g/cm3] Substance content [%] (SO4)2-[%] Length [μm] Thickness [μm] 1. α- Fe2O3 99,62 0,21 2,65 1,62-1,87 1,73 0,35 elongated 1,61 2. α- Fe2O3 99,37 0,36 7,53 0,84-1,39 1,12 0,19 elongated 1,29 3. α- Fe2O3 99,37 0,35 20,14 0,31-0,60 0,49 0,12 straight 1,04 4.
In Fig. 1 are shown comparatively the DTA curves traced for resistor and microwave heating for sample number 1.
The iron oxides morphology have an important influence of solid phase reaction process of barium ferrite W type, meaning that large and very small size grains, according to test results [4], reduce the components reactivity because: - the large size grain powders labelled by SBET= (2-5) m2/g have a reduced reactivity because of low number of contact points which represent reaction starting points are lower as size grain are larger; - the very fine powders with SBET= (10-20) m2/g induce a low reactivity because in heating process take place a fine particles concentration due to sintering process, and the number of point-like contacts are lower; - the optimal size grains regarding the solid phase iron oxides reactivity lie in range SBET= (6-8) m2/g.

The average grain sizes in all samples are less than 100nm.The average grain size changes with the sintering conditions.
So, it seems that the uniformity of grain sizes and orderliness of grain array are beneficial to the transparency and integrity of the ceramics.
The grain sizes of the ceramics are 50~80nm.
In addition, it is found that the uniform grain sizes, round-like grain shapes, ordered grain array and fewer pores are beneficial to the transparency of nano-ceramics.
Acknowledgements This work was supported by NSFC of China under grant number 50272040, Fok Ying Tong Education Foundation under grant number 91046, and Youth Foundation of Science and Technology of Sichuan Province under grant number 03ZQ026-039.

On all EBSD maps shown in the following figures Cube grains are marked blue, S grains – green, Cu grains – red and Brass grains – yellow.
To compare the nucleus density from different nucleation sites, the number of nuclei developed from large Cube bands was also counted.
The results revealed 42 recrystallized Cube grains from 24 large Cube bands on the same sample area, i.e. on average 2 Cube grains per large Cube band.
In general, it is well known that the Cube orientation has a highly mobile high angle grain boundary with S-grains due to a special 40°<111> orientation relationship.
Hence, Cube nuclei with highly mobile grain boundaries to S-grains were preferred and showed the highest growth rate compared to nuclei having grains of other orientation as next neighbors.

In addition, if the number of unique EFGs increases their respective fractions have to be smaller.
For coarse-grained materials with a grain size > 1 , the volume fraction of atoms in the grain boundaries is negligibly small, but for 100 nm grains one calculates already a volume fraction of 3%, which increases for 10 nm grains to 30% and might reach 50% for 5 nm grains [2].
Spikes are formed for a very short time in systems having a mean atomic number larger 20 [49].
The number of possible sites for probes increases.
Small numbers of probes can be deposited as a two-dimensional sub-monolayer.