Search results

The large ferrite grains (first layer) of fairly well-conducting materials are separated by grain boundaries (second layer) of relatively poor conducting substance.
Thus the number of Fe2+ ions responsible for dielectric polarization becomes maximum.
Therefore ferrites with large number of Fe2+ ions are likely to exhibit a higher dielectric constant [13].
The smaller dielectric constant under investigation is also attributed to smaller grain size of these ferrites.
Lower AC conductivity of samples under investigation is attributed to smaller grain size of the ferrites.

When γ is increased further the films show mixed amorphous and microcrystalline phases with increases in amorphous component in the "lm structure with the shifting of TO phonon peak to lower wave number 520 cm-1.
When boron atom gets incorporated in Si atomic configuration, it gives rise to an elective doping state with a stress developed on the surrounding atomic network producing disorder in film structure and as a result TO phonon peak shifts to lower wave number.
Atomic hydrogen can easily fill the unsaturated B–Si bonds which are formed by the boron dopant atoms reacting with the Si grains.
The majority of the inactive neutral B–H–Si complex exists in the interface between grains (i.e., in amorphous region) while the unsaturated B–Si bonds can exist mainly in the grains or in the grain boundaries [15].
This is not beneficial for the forming and growth of nanocrystalline silicon grains.

The influences of the various welding parameters in the PTA process have already been explored in a number of studies [3-5].
The Ni-matrix exhibits high resistance against sliding, grooving, grain sliding and grain rolling wear as well as strong corrosion resistance and high impact and pressure resistance.
The standardized quartz sand used in this test has a grain size of 213-300 µm.
The segregated carbide accumulates at the grain boundaries as can be seen in the optical microscope images (OM).
After heat treatment (Fig. 5) the matrix exhibits a large number of finely dispersed precipitations with sizes of up to 250 nm.

Introduction Equal-channel angular extrusion (ECAE) is at present one of the most promising technique to produce bulk nanostructured or ultrafine-grained materials (grain size in the range of 100-1000 nm) for structural applications.
In this study, metals with different purity levels and grain size have been chosen, e.g.
The silver samples had a grain size of 40 µm.
The number of ECAE passes was limited to 3.
Their associated shifts from respective ideal positions vary with the number of passes.

The viscosity of the semi-solid metal alloy is dependent on a number of metallurgical parameters including the solid fraction, solid particle size and morphology, particle distribution, chemical composition and pouring temperature [11].
It can be seen that most a-Al grains were developed in globular or rosette form with an average grain size of approximately100 mm.
The microstructure of the alloy consists of a large portion of primary Mg2Si and Si particles co-existing with globular a-Al grains, as shown in Figure 2b.
However, the cluster formation in the Al-15Si-10.5Mg-4Cu alloy was more severe; a number of primary Mg2Si and Si particles enclosed by a-Al grains wrapped up together to form large clusters (Fig. 3b).
Charrette, Microstructure and rheological behavior of grain refined and modified semi-solid A356 Al-Si slurries, Acta Mater., 54 (2006) 3503-3511

Isothermal LCF Behaviors of a NiCrAlYSi Coated Columnar-Grained Directionally Solidified Nickel Base Superalloy Hui Chen YU a, Bin ZHONG and Xue Ren WU Beijing Institute of Aeronautical Materials, Beijing 100095, China a huichen.yu@biam.ac.cn Keywords: Coating/substrate system; Directionally solidified nickel base superalloy; Fatigue life; Low cycle fatigue.
Introduction DS superalloy is superior to conventionally cast superalloy, because the elimination of the grain boundaries normal to stress axis enhances elevated temperature ductility and DS process provides a preferred low modulus [001] texture orientation parallel to the solidification direction.
The alloy microstructure consists of regularly packed cuboidal γ' particles in a face-centred cubic (fcc) γ matrix within a columnar grain.
The crystallographic [001] directions of the columnar grains were aligned parallel to the specimen axis.
The number of cracks was increased with increasing test temperature and strain range in most cases.

In the long-term farm crops experience, the main body agricultural production pattern had already formed which is the grain, the fruit industry and the animal husbandry.
The sample were air seasoned after having rejected impurities , plant thin root, the grain size analytical investigation were carried on method [15] which was combined the screen analysis law and the sucker law, groups experiment was 57 altogether.
Assuming self-similar structure of soil are consisted from the porous soil particles of different sizes, then the soil particle quality distribution and all levels of average grain diameter's fractal relationship is in the equation (1)[17,18]:
（1） In the equation (1), is the determination criterion, is the fractal dimension; is the soil particle mass which is smaller than for the particle size accumulates, is the maximum grade average grain diameter, average grain diameter is , is expression all levels of soil particle mass sum total.
（ 3） Where: is the mass fractal dimension, is the clay content, is the sand grain content, is the thick silt content.

There are huge numbers of the metallic implants available in the market and 316L stainless steel is one of the well-known metallic implant being used.
These deformation twins seem to initiate from the existing grain boundaries.
At larger cold reduction (30 %RT), almost polygonal grains change to elongated grains with higher intensities of deformation twins (Fig. 1 (c)).
The changes of grain structures were extremely observed after 50% cold reduction.
It clearly seen in Fig. 1 (d) that an elongated grains has replace the existing coarse grains.

However, a number of studies [7-11] have revealed that it can be difficult to achieve satisfactory properties when welding high strength titanium alloys.
(a-b) The amount of α equiaxed grains increased with the distance from the fusion line.
(c-d) Some elongated α grains were found near the fusion line, surrounding withβ-transformed fine acicular α.
The amount of α equiaxed grains increased with the distance from the weld center.
Note the quenched coarser grains in the HAZ compared to the base metal.

It is sort of the regular granular grains.
Shape factor K represents the circularity and if the value equals to number one, it means that it is circle but if the value equals to number zero, it means that it is straight line.
During the solving of given task, we decided to create the automatic model generator which operates on the base of generating of random numbers [7].
The mentioned characteristic data were obtained on the base of visual image analysis of the experimental material: · number of graphitic grains for 1 mm2: 100 ÷ 300 units, · average diameter of graphitic grain: 0.01 ÷ 0.08 mm, · area proportion of graphite in the structure: 4 ÷ 12 %.
The portion of graphitic skeleton depends on crystallization rate (growth is subjected to diffusion of carbon) and amount (proportion and number) of eutectic units especially depends on number of nuclei in molten mass (treating agents).