Search results

Nevertheless, the fabrication of such ultrafine cemented carbides presents a number of issues related to manipulation and pressing of finer powder mixtures and control of faster WC grain growth kinetics [4].
SEM images were used to measure WC grain size distributions.
In the absence of VC and Cr3C2 (mixture hm3), the Vickers hardness decreases continuously as the HIP temperature increases, in accordance with the expected grain growth of WC grains.
It is worth noting that, in any case, WC grain inhibition is not complete since WC-Co alloys containing up to 1 wt. % of VC show grain growth after prolonged treatments at high temperatures [20].
The fact that the lower hardness at 1200 ºC is more clearly appreciated in the material with the finest WC grain size after vacuum sintering (i.e., hm1) is also compatible with the activation of mechanisms based on coalescence since this material presents higher WC-Co surface area and a lower Co mean free path, which implies a higher number of potential WC-WC contacts.

There are 3 basal, 3 prismatic, 6 pyramidal , and 12 pyramidal slip systems in Ti, and these 4 types of slip systems are numbered from 1-3, 4-6, 7-12, 13-24, respectively in Table 1.
The numbers are marked in the SEM images for slip trace analysis.
The black lines are the slip traces in representative grains, and black numbers (ranging from 1 to 24) correspond to the slip system listed in Table 2.
The number within white brackets is the grain number in Table 2.
A crack formed in the slip traces in crystalline grain #106 and it extended into the adjacent grain.

Statistical Analysis of Histograms of Grain Size Distribution in Nanostructured Materials Processed by Severe Plastic Deformation A.
Studies have shown that bulk metal materials with structure, in which crystallites with sizes less than 100 nm, limited by high-angle boundaries, predominate, can be formed only by a limited number of methods.
In all these works, the results are represented as histograms of size distribution of grains.
The analysis of the histograms of grain size distribution was carried out in two stages.
Ditenberg, On the limiting minimum size of grains formed in metallic materials produced by high pressure torsion, Phys.

The sample was milled to 60 μm on 2000# sandpaper and then punched into a number of wafers with a diameter of 3mm.
Many small recrystallized grains appear around the grain boundaries of the large grains, with an average grain size of 20μm.
As the number of passes increases, the intensity of diffraction increases continuously.
There are many small recrystallized grains with rigid nucleation around the grain boundaries of large grains, and the grain boundaries between them are small angle grain boundaries.
There were many small recrystallized grains at the grain boundaries of large grains, and the grain boundaries between them were small angle grain boundaries.

However, the number of simulated subgrains may still be too small to give reliable results.
In order to detect these grains a large number of grains has to be measured.
One important result is shown in figure 6a which displays the number of grains of a particular number of corners over there orientation distance to the Goss orientation.
According to the von-Neumann Mullins theory ([35]) grains which have a geometrical growth potential should have a significantly higher number of corners than others.
In brief it assumes that Σ9 grain boundaries have lower energy than others and that Goss grains meet a particularly high number of Σ9 grain boundaries in the primary recrystallised matrix.

During the subsequent ECAP process, β- Mg17Al12 phase and Mg2Si was broken gradually with the increasing of ECAP pass numbers.
For the 4-pass processed sample, more grains were significantly refined, but distributed inhomogeneously, coarse grains are surrounded by fine ones, which is called as bimodal microstructure [15].
For 2-pass ECAPed sample, small part of grain was refined while β-phase is discontinuously distributed interaction of grain size and second phase make it have the similar corrosion behavior with the as-cast alloy.
With increasing of ECAP pass numbers, the corrosion type changed from pitting corrosion to general corrosion.
Saito, Improving both strength and ductility of Mg alloy through a large number of ECAP passes, Mater Sci.

The samples subjected to different holding times were differentiated by the numbers of hours following the denotation, e.g., S1-1 and S2-1 for the samples holding for one hour.
Care must be taken in selecting the H-P parameters, σ0 and ky, because they will be influenced by quite a number of factors concerning the materials characteristics, and the values in the literatures differ significantly.
Concerning the continuity conditions imposing multiple glide on polycrystal, M was taken as the Taylor orientation factor, being related to the number of operative slip systems in the polycrystalline aggregate [24, 25].
If we define a volume in the structure with hard particles on grain boundaries of ductile polycrystalline matrix to deform as an integral, apparently, the number of operative slip system in the hard particles is zero, and then the total number of slip systems in the whole volume is reduced.
We define this volume element as the one consisting of the composite of ferrite matrix and cementite particles distributed homogeneously on the grain boundaries, and the number of both grains and particles are sufficient in the element.

Small new grains formed at triple points and more rarely within grains.
This was particularly important as etched NaCl creates unwanted topography that reduces the number of successfully indexed pixels.
Orientation filtering to remove "noise" in maps proved very useful and reduced the number of artefact subgrains, which were often single or double pixels along boundaries.
At this very low misorientation the EBSD maps showed the subgrain boundaries and the correlation with LM was good but the number of artefact boundaries also increased.
Some long subgrain boundaries cut completely across a grain, dissecting it into two smaller grains.

SP processed ZnOs, in comparison to commercial one, had smaller both grains and agglomerates of grains.
Under reducing conditions the sensor resistance decreases proportionally to the number of oxygen ions desorbed by alkyl radicals.
This resulted in a large specific area of the grains and a larger number of oxygen ions adsorbed at grain boundaries.
The greater number of adsorbed ions showed a greater potential for being desorbed by the reductive gases, that is better sensitivity.
When it comes to the sensor's high resistance in the air, it can be ascribed to the greater number grains and potential barriers, as the SP processed ZnO was composed of smaller grains than that commercially available ZnO.

With the cooling rate decreasing, when t8/5 = 60s, the original high angle austenite grain boundaries gradually disappeared, eutectoid ferrite grains occured at the original austenite grain boundaries, lath bainite, granular bainite and granular ferrite are generated in the original austenite grain.
As can be seen that when t8/5 = 30s, due to rapid cooling rate, the number of M-A constituent is little, and strip M-A constituent distributed in ferrite matrix directively (Figure.2a).
With the cooling rate decreasing, when t8/5 =60s (Figure.2b) , M-A constituent changes significantly, gradually change from strip to block, the number and density increased.
STE355 Steel Microstructure after Welding in the Grain Shell and its Effect on Toughness.
Zr microalloyed HSLA steel coarse grain heat affected zone microstructure and properties.