Search results

This is due to the increased distance between coarse particles at grain boundary.
SCC resistance i.e., the immersion cycle number until fracture increased in all three alloys when they were over-aged.
Grain boundaries were further investigated with TEM to elucidate the SCC mechanism.
Both of these lie along the grain boundaries.
This galvanic cell is believed to facilitate the crack propagation along the grain boundaries as shown in Fig. 3.

A limited number of studies have aimed at enhancing the efficiency of the joining process by reducing the IMC layer thickness.
Consequently, the heat in this zone is only partially employed in grain refinement and growth, resulting in the formation of elongated grain structures.
In the AA 5083 base metal, microhardness ranges from 95-100 Vickers Hardness Number (VHN) under annealed conditions, decreasing to 78-84 VHN toward the weld centerline due to the formation of ultra-fine grains from recrystallization.
Steel fragments in the Nugget Zone (NZ) also contribute to microhardness variations, ranging from 80-310 Vickers Hardness Number (VHN).
The thermal gradients during Friction Stir Welding resulted in mechanical refinement, yielding ultra-fine grains in the stir zone, while adjacent Heat Affected Zones exhibited long and elongated grains.

In this condition, a volume V contains a random number of centres N following a Poisson distribution with average value ӨV.
Then a random set is obtained by the union of random grains (spheres or sphero-cylinders in Fig. 1, but more generally any compact set).
It appears that a Boolean model with anisotropic primary grains (for instance sphero-cylinders) shows a much lower percolation threshold (0.01145 for an aspect ratio l/r = 100 [9]) than for isotropic grains (0.2895 for spheres [7,10]).
For any realization of this RF, a Poisson point process with intensity Ө(x) is generated (for any realization, the number of points in a domain D follows a Poisson distribution with average Ө(D) = ∫D Ө (dx)).
It shows that a typical homogeneous distribution of grains in space (like for the standard Boolean model) does nor produce a medium with optimal properties.

The results also show carbon partitioning does not only take place in a single austenite grain, but carbon segregates into several adjacent austenite grains rather easily, as shown in Figure 4(B4).
The VHN hardness in Figure 5 also indicated that the second phases (the martensite distributed in the matrix of granular bainite) with much higher hardness numbers.
It is high enough to diffuse in the grains in seconds to minutes.
To simplify the situation, only one austenite grain is considered.
The evidence of B3 in Figure 4 has shown that holding at 450 ºC for 10 minutes, more large size of MA was formed with a high hardness number.

By milling only Mg2Ni, nanostructured Mg2Ni composed of the intra- and inter-grain regions was obtained (x = 33).
The coordination numbers and interatomic distances of the Mg-D and Ni-D correlations in the amorphous MgNi-D show that deuterium occupies the interstitial tetrahedral site composed of nearly [2Mg2Ni].
The coodination numbers n and interatomic distances r of the Mg-D and Ni-D correlation in MgNiD1.6.
All the diffraction peaks are rather broad, due to nanometer-scale grains with a high lattice-defect concentration.
Heat treatments for both the grain growth and strain-release of crystallites are necessary for further improvements of the hydriding properties.

In addition, grain matrix refinement and enhanced particle distribution were obtained after each FSP pass.
Also the dispersion of Al2O3 particles in the stirred area became more homogeneous and the average hardness improved by increasing the number of passes.
After several trials, these parameters were selected for the study; tool rotation speed of (750, 1250, and 1750) rpm, number of passes were (1, 2, and 3) passes with constant travel speed of 50 mm/min and verbosity duration of 20s, and the number of samples were selected based on Taguchi array for controlled factors, which gives nine deferent samples.
The corresponding (OA) depending on the number of variables used in the experiment and their levels.
The augment in hardness was attributed to fine dispersal of Al2O3 particles and fine grain size of the aluminum matrix [15].

Presently we have prepared different grain sized Bi2O3 powder by ball milling process.
During the reduction of grain size by ball milling process large number of defects has been introduced in the as prepared samples.
Therefore compared to the un-milled sample (grain size ~ 194 nm) positrons annihilate more at the grain surfaces in the milled samples (grain size < 100 nm).
The bulk NiFe2O4 in its coarse grained form is a fully inverted spinel structure with equal number of A and B sites filled by Fe3+ ions [53].
Thus, as seen from Fig. 25, the samples of grain sizes 3.5 nm and 4.8 nm are normal spinels and those with grain sizes 5.6 nm and 6.8 nm are combination of normal and inverse spinel molecules.

Chip dimension, pin number and distance between pins are specified in details in the assembly dimension of components.
(2) Positioning Speed The number of chips on 2 inch LED crystals is 15218 and it takes 26,492 ms for positioning.
Therefore, the positioning speed is calculated as 15218 / 26.492 = 574.44 grains/second.
Experimental result showed that an imaging positioning accuracy error of less than 1 μm and a positioning speed of 574 grains/second were achieved.
Research on Automatic Point-measurement System for LED Grain．XIAN University, 2004,34( 2),p6-9

The unreasonableness of the replacement of aluminium nanopowder to coarse-grained powder in this reaction due to the low efficiency is shown in the article.
At the same time, for wide use of hydrogen energetic it is necessary to solve a number of problems
The rate of hydrogen emission was only 0.14 ml/(s·g) in reaction with coarse-grained aluminium powder.
Summary The research has shown that aluminium nanopowders have higher reactivity than coarse-grained aluminium powders.
The rate of hydrogen emission was only 0.14 ml/(s·g) in reaction with coarse-grained aluminium powder, and amounted 9.5 ml/(s·g) in reaction of aluminum nanopowder with water.

It has been shown that the quench rate has an important role on formation of grain boundary precipitates [3,4].
They found the grain boundary precipitation to influence the subsequent crack propagation.
The number of natural aging (NA) days following the SH is indicated on top of the graphs.
The number of natural aging (NA) days following the SH is indicated on top of the graphs.
The number of natural aging (NA) days following the SH is indicated on top of the graphs.