Search results

Herewith, the casting possesses a fine-grained structure an does not have burning-on.
The authors of the papers have conducted a number of studies of the pouring temperature influence on the structure and properties of tin base bronzes.
With the increase in the casting thickness and a rise in the pouring temperature the number of equiaxed crystals rises.
In thin (5 mm) sections, as a rule, a fine-grained structure was observed irrespective of T value.
Such samples had coarse grains and significant porosity.

The development of extremely sharp cube texture in the 8 cycle processed material could be attributed to the oriented nucleation of cube grains at early stages of recrystallization and subsequent growth of these grains.
Fig.1(a) is the grain boundary (GB) map in which the high angle grain boundaries (HAGBs with misorientation angle θ>15°) and low angle grain boundaries (LAGBs with 2°≤θ≤15°) have been highlighted in black and light grey lines, respectively.
Presence of significant number of off-cube oriented grains could be easily observed in the microstructure in this condition.
Oriented nucleation of cube grains plays a significant role in the formation of the sharp cube texture.
Legoues, Orientation Dependence of Grain-Boundary Critical Currents in YBa2Cu3O7-δ Bicrystals.

But the alloys commonly used for thixoforming are limited to a few casting alloys and only a limited number of trial have been carried out on wrought alloys.
One coarsening mechanism is the coalescence of the grains, joining together and leaving an entrapped liquid pool in between the two grains.
Another grain coarsening mechanism is likely to be the ripening [4], in which the large grains grow and the small ones remelt.
The grains grow and turn into globular ones through the movement of the grain boundaries.
When the specimens were reheated at 609℃ and 622℃ for 0-30min, the average grain size of grains was 106-124㎛ and 82-91㎛, respectively.

To determine the nature of the distribution of the length of the grains and area of the grains for NdNiO2 (S1) and Sr doped NdNiO2 (S2 and S3) system respectively, a collective number of grains are randomly chosen from the respective micrographs estimating the grain length and grain area for each cases by using the ImageJ software.
Similarly, Fig. 7 shows the percentage grain count versus the grain area for (a) S1, (b) S2 and (c) S3 respectively.
The presence of a large number of very small grains alongside a few larger ones can lead to anisotropic material properties.
To observe the grain length and grain area, the scanning electron micrographs are taken of respective samples.
Grain length and grain area distributions for respective samples are analyzed.

The ECAP is very often used for the improvement of strength properties of aluminium alloys by converting the conventional coarse grained metals into ultra-fine grained materials.
A grain size of 40-60 mµ was revealed before processing.
The experimentally measured stress and microhardness values are presented in Fig. 2 as a function of the ECAP pass numbers.
It is seen that briefly a high value of maximal value of stress (and hardness) in each pass will be achieved by the ECAP processing. 0,00 200,00 400,00 600,00 800,00 0 2 4 6 8 10 pass number σmax 0 30 60 90 120 150 microhardness stress microhardness Fig. 2. a) Values of maximal stress and microhardness as a function of ECAP pass number, and b) the TEM microstructure after ECAP processing through 10 passes.
Finally after fourth stage the average size of the grains is between 1 and 3 mµ .

A number of models for precipitation kinetics have become available in the last years; these have been combined with thermochemical and thermokinetic databases.
Due to the fact that precipitation occurs at the grain boundaries, the growth won't be only volume diffusion controlled.
The parameter λ2 (0.6<λ2<1) reflects the contribution of the grain boundary diffusion of Chromium on the growth kinetics of the Chi precipitates (λ2≈0.6 means only grain boundary diffusion controlled).
There are, however, a number of factors that require further analysis.
Acknowledgements The authors are grateful to the Netherlands Institute for Metals Research (NIMR) for the provision of funding through the programme "Designing ultra high strength corrosion resistance steels for aerospace applications" (project number ) and "Tailoring of processable metastable steels" (project number 02EMM30-3).

Fig. 4 shows the change in the number of precipitates, the size of the precipitates and martensite lath width with increasing aging time.
Variation in the size of the precipitates, the number of precipitates and the martensite lath width with aging time.
Phys., 87 (2000) p. 805 The grain boundaries act as obstacles to the movement of the domain wall.
The domain wall energy is influenced by the atomic structure of the grain boundaries [9].
Therefore, in the case where the grain size is large, the grain boundary area and domain wall energy will be lower.

Negative segregation at the bottom of ingot forms due to the interaction of solidification interface and equiaxed grains deposition during solidification.
Up to now, only a limited number of industrial investigations were reported in literatures.
In the porous region, the liquid velocity can’t be seen in Figs. 6(b) and (c) even if the liquid penetrate through the packed layer of the grains.
In the slurry region, the solid of equiaxed grains are free to move in the surrounding liquid and its velocity appears obvious in the ingot.
[3] M H Wu, A Ludwig, Modeling equiaxed solidification with melt convection and grain sedimentation—I: Model Description.

In general, the metals and alloys having FCC lattice structure possess sufficient number of independent slip systems that can be activated at room temperature and therefore can be extruded at room temperature.
The equi-axed grains are of the size ~ 100 um.
These elongated grains resemble the original grains in as-cast conditions in terms of their volumes.
Some of these regions however do recrystallize but grain growth is restricted and thus these regions form a distinct colony of fine grain size (< 5 µm).
A higher degree of deformation (higher extrusion ratio) significantly lowers the volume fraction of unrecrystallized grains and improves the grain coarsening in the recrystallized grains.

Appropriate plane slots number of the container yard is of great importance to the sustainable development of low-carbon container ports.
The calculation of plane slots number of container yard has always been one of the key problems for container port.
Reasonable slots number and yard layout can save land resource as well as improve the port productivity.
Therefore, the optimal storage yard space is 230 TEU per 10000 TEU throughput and the corresponding plane slots number is 51.
Wang, Container terminal operations to receive payment amount and the yard area of research, Grain Processing. 12 (2010), 74-76