Search results

(a) (b) Fig.3 Orientation dependence of active slip systems, (a) number of active slip systems as a function of orientation at 0.003 tensile strain, (b) active slip systems predicted by Schmid law Fig.5 Average number of active slip systems vs. tensile strain Fig.4 Evolution of number of active slip systems with tensile strain 3.3 Slip system activity.
In this study, the number of active slip systems in a grain is determined to be the smallest number of the slip systems necessary to account for 90% of the total absolute accumulated shear of the 12 slip systems [10].
Fig. 3(a) shows the orientation dependence of the number of active slip systems at the early stage of deformation (0.003 tensile strain), from which it can be found that the (100), (111) and (110) oriented grains have respectively eight, six and four active slip systems.
The evolution of the number of active slip systems with tensile strain is given in Fig.4.
The simulation results show that: (i) there are few grains having one, five and seven active slip systems throughout the deformation, and all the grains activate more than one slip system after a very small strain; (ii) the number of grains with four, six and eight active slip systems increase as the tensile deformation going on, but at relatively large strain, the grains with four slip systems decrease, these behaviors are obviously related to the rotations of grains to the directions of (111), (100), and the (100)-(111) line; and (iii) grains with two and three active systems decrease with tension because more slip systems are needed to accommodate large deformations.

The role of mobile and immobile dislocations, grain boundaries, and pores is regarded.
Grain boundaries.
Then the vacancy flux near the grain boundary is 4aD/d2, and the number of vacancies, coming to a grain boundary per unit time, and calculated per unit volume, is 24aD/d 3 , which, on the other hand, may be written as (〈N 〉 − Ne)/τ = a/dτ.
From this follows that 1/Dτ = 24/d 2 for grain boundaries, which means that the mean free path of the excess vacancy inside a grain with respect to the grain boundaries is about 0.2d.
On the other hand this number is equal to the number of annihilating on dislocations vacancies per unit time, (〈N 〉 − Ne )/τ = −(a/2τ)ln(8.54lj2ndt).

Introduction The nanostructured (NS) (< 100 nm) or ultrafine grained (UFG) (<1 µm) materials can result in dramatically improved -or different- properties from conventional grain-size (>1 µm) polycrystalline or single crystal materials of the same chemical composition.
Manufacturing BNMs with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering.
If some unique properties are limited to the finest grain sizes, methods must be found to stabilize the grain size while attaining theoretical density and complete particulate bonding.
The number of initial mesh (4 node isoparametric plane strain element) was 1000.
This number of elements was found to be sufficient to show local deformation of the strain rate insensitive workpieces by calculating with varying the number of elements.

Evaluation of texture and structure were carried out using the orientation distribution function (ODF) restored from the X-ray direct pole figures and the large number of individual orientations measured by the EBSD method.
The volume fractions of low angle grain boundaries (LAGBs) and high angle grain boundaries (HAGBs) were 30 and 70%, respectively.
The main reason for low ductility is associated with an insufficient number of deformation systems, activated at these temperatures due to the hexagonal crystal lattice type of the alloys with a high ratio c / a.
The distribution function of orientations (ODF) and the volume fractions of the main orientations were calculated using Gaussian approximation of a large number of normal distributions [7].
It should raise the average grain size to 10 μm by the subsequent annealing.

The sample comprised at least 200 grains.
The contribution of grain boundary sliding (GBS) to the total deformation was calculated from the formula [10]: , (1) where h is the average step height, n is the number of boundaries per unit length on which steps were observed, and k = 1.5 is constant.
A lamellar structure is observed in the bulk of some grains.
The electron diffraction patterns of the structure obtained for an area of 1.4 μm2 show an appreciable number of reflections uniformly distributed over a circle (Fig. 1, a).
This is indicative of the presence of a large number of structural elements in unit volume and of their substantial misorientation.

At the same time, as data of a number of investigations [10] show, a spectrum of boundaries having different misorientations can be formed with plastic deformation.
As seen from the dependence of grain size on deformation temperature, the lower the deformation temperature, the smaller the size of the α- and β- grains (Fig. 1b, 2a).
The microstructure with a grain size of 0.1 µm formed at 450°С.
The study of samples with SMC structure deformed at the lower temperature 550°С has revealed a significant fringe-diffraction contrast, indicating elastic lattice distortion and increased dislocation density in a large number of grains (Fig. 2a).
That is why there are no changes in the grain size-deformation temperature dependence. 2.

A mathematical modelling of the testing situation is very valuable for a number of reasons.
The elastic properties of grains are anisotropic.
The number of points considered for DFT and IDFT are 1024.
Both and depend on the average grain size, single crystal elastic constants and orientation distribution of individual grains.
is the real wave number used in the analysis of the average isotropic homogeneous medium, and .

In this table, α1 means typical size of tungsten carbide grains used as a raw material and α2 means typical size of tungsten carbide grains grown in sintering.
The number of fatigue cycles i.e. the number of rotations was determined by multiplying the rotational speed and the time endured.
From this result, for ultrafine grain cemented carbides, it is difficult to say that the fatigue strength depends on the cobalt content and grain size.
(3) The ultrafine grain cemented carbides did not show a trend that the rotating bending fatigue curve depends on cobalt content and tungsten carbide grain size, which had been reported for conventional cemented carbides
Figure 5 SEM observation of fracture surface of drill blank; material A, deflection 91µm, number of revolution 12,000

The contact area and the applied normal load are used for calculating the hardness number.
The model consists of an indenter, the surface grain in contact with the indenter, and the rest of sample in contact with the given surface grain.
Due to this load the indenter and grain approach a short distance δ1, and the rest of sample and grain approach a short distance δ2.
If the indented surface grain is strongly bonded to the rest of sample, the indentation modulus becomes equal to the Young’s modulus of the grain’s material.
Eg represents the Young’s modulus of the grain’s material.

Brewer's grain protein, homemade [13].
Hydrolyzes of brewer's grain protein hydrolyzed with Alcalase have no inhibitory activity.
With the reduction in the amount of the sample, the number of colonies increased gradually.
MIC of Brewer's grains peptide samples BSG-F3-3-6 for Staphylococcus aureus is 2%.
Ltd. for supplying the Brewer's grains.