Search results

The σr max value decreases noticeably with the increasing number of thermomechanical cycles, then this reduction slows down, and stabilizes after reaching N=30 cycles..
Thus, the grain size decreases from 5-10 microns down to 35 nm (Table 1).
The effect of the number of ECAP passes (N) at 450oC for Ti-50.2%Ni alloy and PDA temperature for Ti-50.6%Ni alloy on characteristic temperatures is shown in Fig. 2a,b.
Characteristic temperature dependences as a function of number of ECAP passes (at 450°С) for alloy 2 (a) and as a function of the annealing temperature for alloy 3 (b).
Ultrafine Grained Materials IV.

This procedure can be generalized by removal of an arbitrary number �e of subcubes.
This is obtained by iterating the generating process an infinite number of times.
We then randomly remove a fixed number of subcubes �e = (33 − �f ).
In general, the number of subcubes will be equal to 2l( ) d, where l is the number of iterations and d = 3.
Snow grain-size measurements in Antarctica.

Moreover, with a large number of CO2 oil displacement technology used in the development of deep well and super deep well, massive costs are directed annually to alleviating and managing corrosion [3-5].
The grain size of quenched and tempered steel is generally subject to its original austenitic grain size.
Fig.7 is the graph of original austenite grain of the steel.
The smaller grain causes more area of grain boundaries and more dislocation density, so ductility and toughness of the steel can be improved.
A great number of dislocation produced because of volume difference occurred in quenching extremely cold condition.

number of donated electrons is proportional to the valence of the ion.
This means that the ions studied behave as donors and that number of donated electrons is proportional to the valence of the ion.
enhances the conduction of the grain bulk breakdown voltage seen in Fig. 2 grain boundaries leads to the assumption that the barrier the defect gradient in the grain.
O both Ti and Ba ions reside mainly in the grain interior decreases towards the grain boundaries.
The singular behavior of Ti ion within the grain interior.

Thus, it is expected that a magnetic field will control the orientation of nc-grains.
On the other hand, there were two peaks in the grain size distribution of the specimen crystallized with a 6T magnetic field, and the peak in the grain size distribution at larger grain sizes was composed of {110} grains.
The TEM micrographs reveal that the number density of nucleated grains in the sample seems to be higher with the magnetic field than without the magnetic field.
rate, the number density of nuclei per unit volume was measured on the TEM micrographs as a function of annealing time, as shown in Fig.3.
There was a good linear correlation between the natural logarithm of the number density and annealing time, and therefore the nucleation rate of grains nN& could be expressed as: ( )btaN expn=&

Groove pressing (GP) is a severe plastic deformation technique for producing ultra fine grain sized microstructures in metals and alloys.
Before pressing, the copper sheets were annealed at 700 o C for 2 h, which gave an average grain size of 78 µm.
Fig. 4 shows the ultimate tensile strength as a function of number of passes for the grove pressed and groove pressed plus cold rolled specimens.
The microstructure of the starting material exhibited equiaxed grains of about 78 µm (Fig. 5a).
Optical microscopy measurements showed grain sizes of 41 µm were obtained after three passes.

Fine-Grained Concretes on Non-Clinker Binders with Highly Disperse Mineral Components D.K.
At the next stage, the number of Bronsted active crystallization centers on the surface of a mineral powder was investigated by the method of determining the exchange capacity with respect to calcium ions [9].
The results of tests to determine the number of active crystallization centers showed that the surface concentration of ion-exchange centers of mineral powders varies unevenly and does not depend on the degree of grinding (Table 1).
This can be explained by the presence on the surface of these mineral fine dispersions of a large number of exchange centers, a significant part of which are acids and alcalines according to Bronsted [6].
To study the properties of fine-grained concretes, 10 cm cubes were prepared using a mixture: a highly dispersed component (Table 2), fractionated sand, obtained by mixing in a ratio of 55:45% of the screening of the Argun deposit and the fine sand of the Chervlenskoye deposit.

From this point, the mechanical performance of TWIP steels can be improved through tailoring their twinning behavior by means of adjusting the grain size and morphology because the two factors will contribute to varied number and configuration of twins and dislocation pile-ups [5].
In the present study, a directional solidification technology was utilized to obtain TWIP steel samples with specially oriented grains and beneficial grain boundary morphologies.
The former possesses an equiaxed grain microstructure with uneven sizes ranged from around 200mm to 400mm while the latter shows a typical columnar grain microstructure distributed in parallel.
Depending on the solidification rate, the diameter of columnar grains was changed from about 200mm to 400mm, in which the medium solidification rate, i.e. 120μm/s, resulted in the finest columnar grains while relatively low or high solidification rate made the grains coarse.
It should be noted that there are several annealing twins in the equiaxed grains but there are not in the columnar grains.

The formation of Mg2Sn precipitates during the dynamic recrystallization process may retard the dynamic recrystallization and slow down the grain growth by precipitation pinning effect at the DRX grain boundaries, resulting in a finer grain size.
Also at 300 ºC, the grain size is much lower in AT33 than AT32.
At 350 ºC, the DRX grain sizes are similar.
During deformation, new grains form along the initial boundaries, but stop at a certain size, allowing new layers of DRX grains to form of the same size.
Conclusions The main results from this study can be summarized as follows: · Peak stress and peak strain increase with increasing number of precipitates

The drilling forces and protrusion heights of diamond grains were measured.
The drilling forces also increased with the numbers of drilled holes due to the wear of diamond grits.
Finding a way to simplify machining process is one key to achieve cost-efficient grain machining.
Hole numbers (N) 2 4 6 8 10 Fz (N) 0 200 400 600 800 1000 1200 1400 1600 1800 Forces for the first phase Forces for the second phase Fig.4 Cutting forces versus the number of holes The cutting forces variation with the holes numbers were shown in Fig. 4.
For the same diamond drill, the cutting force increased with the number of holes.