Search results

If the size-effect could be described mathematically and classified, the number of simulated cases could be reduced essentially.
From other side the workpiece with just several grains in cross section shows the similar flow stress values like a monokristall [3].
So all relevant and key results have to be compared with the part’s volume and grain number.
It is clear, that in simple case the whole material properties results from the number of grain multiplied with the certain property of one grain, e.g. ultimate stress.
Of cause the kinetic inside the material due to grains, subgrains and precipitations evolution should be also investigated.

The results show that the deposits are a Co and Cr solid solution in Ni with a grain size of 6.9~10.6nm, were nearly free of corrosion after neutral salt-spray tested 100 hours.
A number of papers have been published on the electrodeposition of Cr alloys(such as Ni-Cr, Co-Cr and Ni-Fe-Cr) from Cr(Ⅲ) electrolytes[4-9], these coatings, which possesses high strength, good wear resistance, corrosion resistance, and thermal stability, have attracted much attention.
The crystalline structure and grain size of the coatings was determined by X-ray diffractometry (XRD, D/Max2500).
Conclusions The Ni-Co-Cr alloy coatings were successfully fabricated on a low carbon steel substrates from a chromium sulfate bath, which are a Co and Cr solid solution in Ni matrix with a grain size of 6.9~10.6nm.

Moreover, phenomena such as plastic deformation, residual stress and changes in grain structure occur around the cracks’ tips, which affect the process of crack propagation significantly.
X-ray diffraction, a method can reveal the changes in grain structure resulting from stress and plastic deformation is the most popular one.
This study is an attempt to establish a theory correlating the stress ratio with plastic deformation, residual stress and changes in grain structure at the crack’s tip.
In the two first tests, maximums loads of 16.24kN (test number: A-1) and 13.54kN (test number: A-2) were applied under a stress ratio of 0.1.
Furthermore, loads of 24.37kN (test number: B-1) and 20.30kN (test number: B-2) were applied under a stress ratio of 0.4.

The vapor created a large number of nucleation sites which led to the fine-grained microstructure.
Large SiC crystals were growing towards and on the expense of the small grained fibers.
It consists of SiC grains with lengths of up to 300 nm and a high density of stacking faults.
The matrix consists of small SiC crystals (<300nm) within large Si grains.
It was found to consist of small SiC grains of various modifications within large silicon crystals.

As a consequence, a number of researchers proposed using the same FSSW tool/ machine in the process of exit hole refill.
The grains in HAZ are coarser than in stir zone (SZ), while precipitates in HAZ are slightly finer than those in SZ.
This stir zone (refill stir zone) is composed of very fine nearly equiaxed grains.
From this micrograph the grain in this zone is estimated to be about 4 microns.
b) The microstructure obtained after the refill stage shows a new stir zone around the smaller pin; this stir zone consists thin film of very fine equiaxed grains and TMAZ with elongated grains in the vertical direction of the metal flow.

Fig. 11 shows the Vickers hardness number variation as a function of annealing time at various temperatures.
Below 773 K, the Vickers hardness number does not change much with increase of annealing time [19].
It is well known that the polycrystalline binary Ni3Al alloys are generally brittle because of the grain boundary weakness [1-3].
The foils just after primary recrystallization composed of very fine grains (~3µm in average) are found to be similarly brittle.
Details mechanism of the recrystallization and grain growth in our Ni3Al foils is described in our previous paper [21].

The main recombination of charge carriers and perovskite degradation occur at grain boundaries (GBs) and interfaces, due to the poor density of deep traps inside perovskite grains [51,52].
The main interaction between perovskite precursors and additives‎ correlates to a greater extent with the donor number (DN).
As a result, this interaction promotes a higher crystallization rate (i. e. the formation of a larger number of nuclei, and thus, smaller crystal grains) [34], leading to some decrease in the device efficiency.
Cross-linked Grains.
Reducing the defect density can be achieved by: (1) increasing the size and quality of crystal grains, (2) forming cross-links between perovskite grains, and (3) passivating the defects at GBs.

The process of diffusion metallization of Ti50Ni48.5Co1.5 onto steel 3 was carried out in a modernized processing facility (patent number 2430191), which allows a coating to be formed in a single process cycle and produces surface plastic deformation of the workpiece.
Results and discussion The main parameters of the process that affect the structure and quality of coverage include the number of cycles of "dipping" the product into the melt, the temperature of the low-melting point of the melt and its chemical composition, the diffusion of saturation, and the composition of the transport medium for the melt.
Some of these parameters (composition of the melt and transport of inert atmosphere, the number of dipping cycles) are chosen based on previous research [6].
Studies of the microstructure of the Ti50Ni48.5Co1.5 surface layer by scanning and transmission electron microscopy at high resolution show that the Ti50Ni48.5Co1.5 coating has a nanosize structure with a grain size of 56–198 nm (Fig. 3).
As a result, plastic deformation occurs, grinding grain size and a more uniform depth distribution layer, a homogeneous nanostructure directionally oriented grain size 50–95 nm.

In the present study, a number of cast Ti-Al-Si alloys were investigated in relation to transient oxide formation in air at 1300ºC.
After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques.
The microstructure of the alloy in cast condition consists of a mixture of grains containing matrix of TiAl with Si rich plates.
Due to this reason a large number of silicide plates were observed in alloys having high concentration of silicon.
Further, this layer had a large number of porosities.

Morphological studies indicate an average grain size of 10 to 15 nm.
To carry out the procedure, the following conditions were respected (table 1): Milling parameters Fe60Co40 nano-alloy Fe 72Al28 nano-alloy Number of balls 18 16 Milling velocity 360 [rpm] 380 [rpm] RBP 50 :1 50 :1 Milling times 2, 4, 8, 12, 36, 54 [h] 4, 8, 12, 16, 24, 32 [h] Nature of milling system Stainless steel Stainless steel Table 1: conditions of development of nano-alloys.
Up to 32h of milling, the average grain size was estimated at 10 nm.
We focused our interest on the evolution of the reflection intensity of the samples for all milling times at 9500MHz frequency (Fig. 3). 0 20 40 60 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Milling time [h] Reflection loss [dB] f=9500 MHz 0 10 20 30 40 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Milling time [h] Reflection loss [dB] f=9500 MHz Fig. 3a Milling time dependence of measured Fig. 3b Milling time dependence of measured reflection loss for Fe60Co40 nano-alloy reflection loss for Fe72Al28 nano-alloy The reflection coefficient's intensity decreased with increasing milling time, this quantity is directly related to the dielectric and magnetic losses [11], the grain size refinement improves the electric and magnetic properties of the materials and has a significant effect on the absorbing characteristic under microwave exposure [12].