Search results

Recrystallised grains can nucleate on pre-existing grain boundaries, deformation bands, such as transition bands or cube bands and the regions with high deformation gradients between second phase particles and the matrix.
We also assume that the higher the number of slip systems activated during deformation, the faster the recovery rate, as described in [12-14].
Results show that some grains, such as the grain marked with the arrow, have been split into several smaller grains during plastic deformation.
Such subdivision or fragmentation results from different parts of the grain experiencing different rotations.
Results show that recrystallised grains are equi-axed with most grains having high angle boundaries.

Si3N4 ceramics usually need to add oxides as sintering additives to promote the formation of liquid-phase for sintering and grain growth.
These results show that as though the rare-earth oxides can purify Si3N4 grains, therefore increasing the thermal conductivity of the ceramics, the excessive oxides that formed at the grain boundary generally deteriorate the thermal conductivity of Si3N4 ceramics.
Rare-earth compounds exist mainly at the grain boundary of the columnar Si3N4 crystals.
Table 1 Sintering formula and Sample number Sample LaF3 (wt%) MgO (wt%) Sample CeF3 (wt%) MgO (wt%) SLa2M3 2 3 SCe2M3 2 3 SLa5M3 5 3 SCe5M3 5 3 SLa8M3 8 3 SCe8M3 8 3 exists as amorphous phase at grain boundary, but there are some crystalline phases detected in the samples.
The rare-earth fluorides can react with SiO2 in the Si3N4 powder; therefore purify the lattice of Si3N4 grains.

A number of organic additives are substances that increase the hydrophobicity of binder grains, which reduces their wettability with water and, therefore, reduces water consumption.
The above literature suggests a number of methods for assessing the resistance of products to moisture: by softening coefficient, water resistance coefficient, water solubility, water absorption, degree of water permeability, and changes in appearance.
On the thermograms of gypsum concrete, as the number of corn cob rods in the concrete increases, the endothermic effect at 120°C decreases.
In pure gypsum stone, about 50% is fine-grained gypsum in the form of prismatic isometric crystals, 15% is medium- and coarse-grained gypsum in the form of individual crystals, which are often fibrous, or rosettes and disorderly clusters of fine-grained gypsum of similar sizes.
Under the microscope, the immersion preparation contains fine-grained gypsum (grain size up to 0.02 mm, short-prismatic shape).

A sufficient number of fibre fibers located in the direction of the acting force can take the tensile force after the rupture of the matrix.
A sufficient number of fibre fibers located in the direction of the acting force can take the tensile force after the rupture of the matrix.
Heavy loaded floors based on fine-grained fiber concrete, Magazine of Civil Engineering. 3 (2013) 7–14
Fine-Grain concrete reinforced by polypropylene fiber, Research Journal of Applied Sciences. 10 (2015) 624–628
The Development of textile fine-grained fiber concrete using technogenic raw materials, Research Journal of Applied Sciences. 10 (2015) 701 – 706

Hardness was determined at two different sites on one side specimens and the mean value was calculated as Vicker's Hardness Numbers (VHN).
The three values were averaged to produce one mean hardness value for each specimen.The measurements were converted into Vicker's Hardness Numbers.
But,VA is described as a large grain ceramic and is also comparatively high in leucite content.
Physical grain or crystal size plays an important part in the surface topography of ceramics.
VA is described as a large grain ceramic and is also comparatively high in leucite content, whereas FI all ceramic systems are described as fine grain.

It can be obviously seen from Fig.3(a) that the coating consists of a large number of gray and black phase and dentrite phase.
It can be seen from Fig.3 (b), (d) and (e) that the most of the TiC grain shows granular in fusion zone and in central region while most grain shows dendritic on the surface area.
And the coating contains a large number of austenite.
So most of TiC grains show equiaxed crystal or close to equiaxed crystal.
They diffused inside the crystal grain of the base metal or on the grain boundary.

Rappaz et al. [1-3] proposed a model to predict the growth of equiaxed grains under isothermal conditions.
The model is based on the assumption that the volume associated with an equiaxed grain can be decomposed into three regions: solid, interdendritic liquid and external liquid.
By combining a solute balance over the three regions, a dendrite tip kinetics model and a local heat balance, the evolution of the grain envelope and its internal fraction of solid can be calculated as a function of the local variation of enthalpy.
In the coarsening stage large precipitates grow at the expense of smaller ones, leading to a reduced number density (Fig. 3a).
The number density and size of the precipitates vary with time; the volume fraction will eventually reach a saturated value which corresponds to the thermodynamic equilibrium at that temperature (Fig. 3c).

In the manufacture of wires designed for the welding of low-alloy fine-grain steels, multiple internal discontinuities appear during some periods that are the cause of major failures (cracking) of the wires.
The analysis revealed that wire cracking in course of wire drawing was due to the superposition of the effects of an inappropriate structure of the initial intermediate product (the presence of polyhedral grains of hard bainitic phase) and unsuitable conditions of the forming process.
Introduction In the course of the manufacture of wires made of G4Sil steel (0.1 % C, 0.9 % Si, 1.6 % Mn) that are designed for welding low-alloy fine-grain steels there appear at certain points of time multiple internal discontinuities which lead to intensive defects (cracks) in the wires.
Fig. 5 Metallographic specimen of longitudinal axial section of the wire, revealing extensive defects of the chevron type and a number of minor defects in the central part of the wire; (LM).
These discontinuities appear in the wire material due to the presence of hard-phase grains of the bainitic type, which are not deformed by wire drawing.

Its microstructure consists on coarse dendritic grains.
The number of the fatigue fatigue marks ranges between 100 to 200 per 1 mm and depends on their distance from the location of the crack initiation (Fig. 2a,b).
Both cracks propagate along the grain boundaries through the interdendritic region.
The drop of the nickel content associated with an enrichment with oxygen and chromium content was observed across the grain boundary decohesion.
It was found that the cracks start at the back face of the turbine wheel surface and propagate along the grain boundaries.

The results show that element Bi in alloys is mainly segregated along the grain boundaries.
Segregative phases increase which appear as the shape of rod and sphere after addition of Bi and mainly separated out along the grain boundaries as shown in Figure 1(b) - 1(d).
Bi is mainly concentrated in segregative phases, it can form eutectic mixture with Ga which can activate Al matrix, the concentration of Bi on grain boundaries may cause intergranular corrosion more serious.
The addition of Bi into Al-1Mg-0.1Sn-0.1Ga shifts the open circuit potentials towards more negative, the reason is the addition of Bi increases the number of segregative phases in alloys which play the role of the activation points.
While the self-corrosion rate of the alloys is also increased due to Bi is mainly precipitated along the grain boundaries resulted in galvanic corrosion.