Search results

It was recorded, that an increasing number of oxygen atoms bonded to the tin atom causes a shift of this characteristic mode to higher frequencies [9].
The other additional peak at 536 cm-1 has reported in [11] as additional mode may be in line with the defect-induced modes due to the surface disorder and a large number of O vacancies and Sn interstitial.
It was found that the bigger nanograins are built up the fiber walls and fine grains were formed in the spongy residue in the internal space of some fibers.
TEM images of a) hollow SnO2 fibers; b) detail of individual bimodal size grains and SAED of SnO2 fiber.
Results of the XRD, SEM, and TEM analyses, showed the bimodal character of the average grain size of SnO2.

The samples were etched using methanolic aquaregia to reveal the microstructure and grain boundaries.
The composition with the high nickel content had a columnar structure with the length of each grain in excess of 1mm.
Fig 2: Microstructure of Al0.3FeCoCrNi1.7 with columnar grains of length > 1mm.
Fig 3, 4: Microstructure of Al1.7FeCoCrNi0.3 showing dendrites embedded in a grain matrix.
This work was partially funded through NASA, under grant numbers NRA NNX11AI73A and NNX13AM99A NSR 475489.

The corresponding JCPDS card numbers for these composites can be seen in Table-3.
The study of dielectric spectroscopy sheds light on the material's composition, grain boundary, grain, transport characteristics, and charge storage capacities.
Instead of the grains themselves, the influence of the dominant grain boundaries can be used to explain the dielectric dispersion.
At higher frequencies, the grains can only have a small dielectric constant, so the grain border is an essential part of how dielectrics behave in solid materials.
These flaws may serve as charge carrier trapping centers, increasing the rate of energy loss and, consequently, the number of dielectric losses.

The physical and chemical properties of a mechanical milled product depends on the rotational speed, size and number of the balls, ratio of the ball to powder mass, the time of milling and the milling atmosphere.
Annealing at high temperatures causes grain growth and the soft magnetic properties decrease.
On soft magnetic materials, a small grain size as possible is desirable (because in this field increases the resistivity), and a mono domain structure in each grain, it is accompanied by a reduction in the coercive force under certain conditions.
The grain size of the powders, treated with high-energy ball milling, and the internal strains were calculated by the Hall–Williamson equation [15].
Variation of the grain size and the lattice strain of Fe60Si40 with milling time.

This is a combined effect of Pd diffusion through Cu grain boundaries and then sideways diffusion through Cu grains.
Therefore, there is almost negligible volume diffusion of Cu from Pd grain boundaries to the Pd grains.
Rapid diffusion to the Pd surface is preferred by Cu atoms instead of entering inside the Pd grains.
Various mechanisms which can alter the stress state during annealing can be conceived: (i) interdiffusion (differences in the atomic volumes and differences in the atomic fluxes of the diffusing species), (ii) phase formation, (iii) grain growth, (iv) excess vacancy annihilation and shrinkage of grain-boundary voids and (v) plastic deformation.
From this discussion it is obvious, that the net (observed) stress change can result from a combination of a number of, possibly competing, sources of stress generation.

Yadav et al [8] investigated the role of current, pulse on-time, pulse off-time, wheel rotation per minute and abrasive grit number on average surface roughness of Al/SiC/Gr Composite with EDDG.
The protrusion of diamond grains will increase on account of dressing caused by sparks.
An iron bonded diamond grinding wheel with grain size #120 was adopted as the tool electrode during the EDDG process.
When these craters cannot be all removed by diamond grains shown as Fig.2 b), a relatively rough surface will be obtained.
The material removal of the workpiece is mainly ground by diamond grains in the brittle removal regime to a rough surface.

Kim studied micro bulk forming by grain and boundary grain elements using finite element model [10].
The effects related to grain size, deformation velocity for the process of micro-upsetting are investigated by Yu Huping [15].
(3) With the established constitutive relation, a simple warm micro-extrusion forming process is simulated using the finite element model with grain and boundary grain elements.
Also, the work is supported by Natural Science Foundation of Jiangsu Province under Award Number BK2006551 and Postdoctor Foundation of China (20060390961).
Finite element analysis of micro-rolling using grain and grain boundary elements.

The grain size LG in the range from 10 to 25 μm does not affect the radiation creep of UO2.
It was assumed that this effect should be observed at grain size by an order of magnitude lower [2].
The initial volume fraction of diffusion boundaries φ0can vary from 10-4 for pure UN (O ~ 500 ppm, grain size 40 μm, metal impurities ~100 ppm ) to 5×10-4 for dirty one (O ~ 2000 ppm, grain size 5μm, metal impurities ~500 ppm) [1].
Na is the number of atoms in volume unit (about 6.8×1022 cm-3 for UN).
Coefficient βi is the number of atoms of U or N, bounded by i-th fission fragment in compound.

Laboratoire de Nanotechnologie et d'Instrumentation Optique (LNIO), UTT, 12 rue Marie Curie, BP 2060, 10010 Troyes Cedex, France a : raphael.moulart@chalons.ensam.fr, b : rene.rotinat@chalons.ensam.fr, c : fabrice.pierron@chalons.ensam.fr, d : gilles.lerondel@utt.fr Key words: Full Field Measurement, Grid method, Lithography, Microscale, White Light Interferometer Abstract: This work deals with the development of a full-field extensometric method at a micrometric scale in order to precisely identify the local features of a metallic alloy at the scale of the grains.
The one chosen here is the win dowed-Direct Fourier Transform algorithm (WDFT) which allows to eliminate harmonics up to the (N-2) order (N is the number of pixels sampling a period of the signal) and to reduce the influence of the uncertainty on the calibration.
The microstructure of the sample observed under an optical microscope has revealed that the average size of the grains is around 30-40 µm.
Moreover, the size of the colour features seems to be in accordance with the grain size (around a few tens of micrometers).
Further investigations have to be made to verify the correlation between the observation of the strain maps and the microstructure and especially, one has to check if these splashes correspond to the grains and express their heterogeneous deformation (due to their different crystalline orientations).

When it is irrational or the irregularity of grain boundary happens or impurities contain, the structure is discommensurate (DC).
And the Fatigue life is an important characteristic of an engineering component, which measured by a number of cycles it can withstand before fatigue failure takes place.
The effects of Co content and WC grain size on the fatigue strength of cemented carbide have been investigated, as plotted in Fig.5 against the compressive fatigue [11].
Fig.8 (a) shows the ratio of number of W and C is 3:2, C atoms are in both sides of W atoms, and Fig.8 (b) shows the ratio of number of W and C is 2:3.
When there are many clusters in the commensurate phase of one wear particle, the frequency in unit time of cycle stress defined as , where is the number of clusters.