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The magnetic properties of two-phase nanocomposite materials depend on the distribution of the magnetically soft and hard phases, the average grain sizes of individual phases, etc. the small grain size improves both remanence and coercivity [7].
In case of pure strontium hexaferrite [11] sample SH 01, σac increases very slowly up to 10 kHz and after 10 kHz, it increases rapidly with increase in frequency, thus confirming the polaron hopping [12] due to presence of large number of Fe3+ ions at the octahedral as well as at tetrahedral sites.
Grain growth mechanism is also one of the important features in prepared composite samples.

Dimensions of micro-wells and pits vary widely, which is caused by significant fluctuations in grain sizes and dispersed inclusions in the steel under study.
The number of microcracks in Fe360 steel samples broken at 213 K (Fig. 1b, f) is greater than in the fracture of samples tested at room temperature.
[6] Li L., Virta J., Ultrahigh strength steel wires processed by severe plastic deformation for ultrafine grained microstructure, Materials Science and Technology. 27 (5) (2011) 845-862
Annealing behavior of ultrafine grained structure in low-carbon steel produced by equal channel angular pressing, Materials Science and Engineering A - Structural Materials Properties Microstructure and Processing. 581 (1) (2013) 104-107

Once the potential of ECAP-deformation for producing ultra fine grain size was recognized, the influence of the above parameters was studied in detail.
For instance, Nakashima et al analyzed the effect of Φ on the grain size reduction efficiency and found that an angle of 90o associated with sample rotation between passes (Route Bc) gave the best results [4].
However, strain distribution within the billet must be considered and reviewing a number of experimental and FEM investigation dedicated to this issue, Valiev and Langdon showed that a "dead zone" is formed at the outer corner when the billet goes through a die [6].
Generalizing, occurrences of this nature are harmful to the microstructural uniformity of ECAPed materials since it is well known that the accumulated strain controls the grain and/or subgrain development, and consequently the strength level [8].

General material properties of Duraform polyamides[3] Average grain size 56 μm 2,20 mil Bulk density 0,45 g/cm3 Density of laser-sintered part 0,93 g/cm3 Mechanical properties Tensile modulus 1700 MPa Tensile strength 48 MPa Elongation at break 24% Flexural modulus 1500 MPa Flexural strength 58 MPa Charpy – Impact strength 53 kJ/m2 Impact strength 32.8 kJ/m2 Ball indentation hardness 78 N/mm2 Thermal properties Melting point 172-180 0C Vicat softening temperature B/50 163 0C Vicat softening temperature A/50 181 0C Duraform polyamide powders are durable and have excellent friction/abrasion resistance and oil/solvent resistance.
Remarks that the powder presents spherical grains and grain size is approximate around 20 μm.
Acknowledgment This work is supported by the Sectorial Operational Programme Human Resources Development (SOP HRD), financed from the European Social Fund and the Romanian Government, under the contract number POSDRU/159/1.5/S/138963 – PERFORM.

. %, on one hand, the CNT conglobation on the grain boundaries made it hard for interfacial integration between CNT and copper (see Fig. 4); on the other hand, copper powder failed to sufficiently disperse CNT due to strong adsorption on the CNT surface, leading to the entanglement of the CNT and thus a sharp decline in density.
Sample A, by contrast, had more defects on its surface with its surface in contact severely burnt and a large number of apertures and flaws.
But CNT, when in large amount, results in its conglobation on the grain boundary, unfavorable for the integration between the CNT and copper[15,16], while more apertures on the surface of the contact would lead to the loose surface structure of the composites, which ultimately increased the abrasion of electric arc on the material.
As the amount of CNT increases, its conglobation on the grain boundary prevents the composites from being fused during the pressing and sintering, thus reducing its density, rapidly raising its electrical resistivity but declining its sliding wears property and fusion resistance.

Zinnwaldite can easily be concentrated from the greisen ore by a combination of crushing, milling, sieving and magnetic separation, potentially complemented by froth flotation for the fine grained fractions[1-3].
To simulate a heap leaching process a column (1 m length x 0.25 m diameter) was filled with quartz at the bottom (5 cm), and dump material from the Tellerhaeuser site: 4 kg coarse grained low grade ore (6-15 mm) and 42.5 kg fine grained low-grade ore (1 to 6 mm).
Acknowledgement The manuscript has been developed within the R&D project FAME – Flexible and mobile economic processing technologies and is co-funded under Horizon2020 by the European Commission, GA number 641650 within the call SC5-11b-2014: Flexible processing technologies.

An increasing diffusion coefficient with increasing nitrogen content was reported in Pd alloys, in which nitrogen atoms fills trapping sites, which are a consequence of the high density of grain boundaries or dislocations [8].
The Nb2Ti alloys studied here are polycrystalline with small grains and contain a large number of grain boundaries, which can form trapping sites for nitrogen atoms and as a consequence, increase the nitrogen diffusion coefficient.

This may can be explained that the microstructure of the N80 steel investigated in this paper consists of upper banite, and material constants m and C can also be effected by both the size and number of the inclusion and cementite of tempered martensite .
This is because that the fatigue crack growth is a consequence of cyclic slip, it is not surprising that fatigue crack prefers to grow through the grains.
Restraint on slip exerted by the grain boundaries is minimal inside the grains.

The catalytic materials which used manganese nitrate, manganese chloride and manganese acetate as precursors respectively, are numbered 1-3(same as below).
SEM and Grain Size Distribution.
It was showed in Fig.4 and Fig.5 that except for the 2# catalytic material, the grain size distribution of TiO2 and the other two catalytic materials was wide, with about 40nm for small particles in TiO2, about 180nm in 1# catalytic material and 240nm in 3# catalytic material.
a (TiO2) b(1#) c(2#) d(3#) Fig. 4 SEM image for TiO2 and three catalytic materials Fig. 5 Grain size distribution of TiO2 and three catalytic materials Surface Area.

According to the data of mineralogical analysis, the sand 1 after fractional preparation involved 60-65% quartz grains; 30-35% quartz-feldspar grains consisting of heavily modified feldspar, quartz, biotite and hornblende; and about 5% individual grains of plagioclase.
The absorbed dose was set according to a preliminary calibration corresponding to the number of table movements at a given speed.