Search results

Nanoceramics materials obtained by nanotechnology are that their crystal grain, grain boundary and their bonding are at the nano level (1~100 nm) among the microstructure of ceramics materials.
Because of the refinement of nanoceramics grain, the number of their grain boundary increases greatly to increase the intensity, malleability and superplasticity of materials greatly and overcome many shortages of engineering ceramics and have the great effect on the mechanical property, electrical performance, thermal performance, magnetic performance and optical performance of materials [2].

In recent years, many research group have developed a number of various combinations of ME composites based on piezoelectric and piezomagnetic materials to get better ME response at room temperature.
The BNT sample shows larger grains with average grain size of 100 nm as compared to composite sample.
The addition of CFO promotes reduction in the grain size with little porosity as reported earlier [3], [7].
The reduction in grain size could be the result of pinning action by CFO in the composite [8].

.% Dy2O3 more homogeneous grains were obtained.
In Fig. 5., it shows that with addition of Dy2O3 the coefficient of friction was lower Large ions of Dy suppresses grain growth.
So, smaller the grain size, pullout of grain is not easy and coefficient of friction lowers.
Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology(MEST) of Korea(Grant number: 2010-00339) References [1] Chi-Woo Lee, Min-ho Youn, Ho-Yen Song and Byong-Taek Lee J.Kor..Inst.Met & Mater.

Figure 5: Residual stresses of the different component variants The fatigue strength of the component also depends on the grain structure of the material which is shown in Fig. 6 for the different variants.
The fine grain structure of the variants V4 and V6 results from the annealing.
The grain sizes of V3 and V5 are similar to each other and in comparison to the others these variants have the coarsest structure.
On the horizontal axis the number of load cycles is shown.
That might be taken as an explanation that they show similar behavior at small numbers of load cycles i.e. in the regime of finite fatigue life Summary The component variants produced by cold forging show enhanced properties in comparison of machined component variants in terms of endurance limit.

Addition of Ag, for example, elevates dissolution temperature of GP zones and addition of Fe slows down aging rate due to refinement of grains [8].
All specimens were equal in average grain size, about 150mm, due to the homogenization at 823K.
The maximum stress amplitude and the number of serration are presented as a function tA in Fig.4 (a) and (b), respectively.
It is clearly seen from Fig. 5 (b) (a) Fig.4 Variation of (a) the maximum stress amplitude and (b) the number of the serration with the aging time at 293K for the Al-6%Zn specimens after quenching from 473K.
It might be thought that grain refinement and/or intermetallic compound formation themselves promote the appearance of serration, but the grain size and the state of intermetallic compound did not alter during the aging.

To reduce the size effect, periodic boundary condition is used to reduce the effect that the number of atoms is less than in a real environment.
Polycrystalline material means in each local region the atoms are arranged in periodic, but on the whole, the orientation and arrangement of atoms in different regions are different, thus forming a structure consisted of many grains in different orientations.
Nano-crystals have large proportion of grain boundaries, so it has excellent properties like high strength, super plasticity and high hardness.
Different from the mechanism of single crystal, there are almost no dislocations existed in the polycrystals with large amount of grain boundary atoms.
This method makes grains too symmetrical and idealistic, so there are some differences between the model and the actual materials.

It can be noticed that grain growth is structurally anisotropic.
The grains in the samples are plate-like, which is characteristic BLSF ceramics [9,10].
It also can be found that the ceramics consist of well-developed grains less pore and clear crystalline boundaries.
The CSBTi-0.1, CSBTi-0.15 exhibit larger grain (average particle size about 8-10µm) as compared with other doped samples.
But when a large number of Ca doping, Ca dopant may substitute A-site Bi ions, low-valent Ca 2+ ions were introduced as acceptor doped to substitute for Bi3+ ions.

Microstructure of the base metal (Fig. 2, a) deformed at the temperatures of β area without HT consists of large β grains with unrecrystallized lamellar α phase in the volume of the grain, grouped into colonies. α phase plate thickness is 0.7 - 2 microns.
In between α colonies and α plates there is β phase grain.
HAZ after welding consists mainly of large grains of pure β phase, detected during rapid cooling, with intermittent release of the second phase observed only at the grain boundaries (Fig. 2, b).
At first fine recrystallized grains formed along boundaries of large β grains.
It is obvious that in the structure of these joints at 750 ºC the number of detected metastable phases, the decay of which at different modes of heat treatment would affect the mechanical properties of the joints, is not sufficient.

Introduction Rock can be represented as an assembly of cemented mineral grains which can be described by its internal microstructures.
The intact crystalline rock consists of a variety of mineral grains of different sizes, and of close contacts between mineral grains and microscopic defects in the form of cracks and holes [1].
Lan et al. [1] developed a grain-based universal distinct element model and studied crack propagation in brittle rock samples with different heterogeneities.
No new cracks generate since number of broken bonds remains zero at this stage.
Moreover, Fig. 5 shows that crack number and type is almost unrelated with heterogeneities.

By the selection, some individuals that show high fitness in the population are chosen and the others for maintaining the same number of individuals at each generation have to be reproduced.
The grinding parameters considered in this study were specimen having a different Mg content, grain size of wheel, table traverse speed and depth of cut in a pass.
Since the higher variation of the S/N ratio at each parameter had the more effect on grinding outcomes, it was seen that the Mg content at specimen and the grain size of wheel dominantly influenced the surface roughness.
Grain size(#) 46 120 200 C.
Ft η S/N ratio (dB) Fig. 1 Experimental results and calculated S/N ratio A1 A2 A3 1.0 1.5 2.0 2.5 3.0 3.5 4.0 S/N ratio for Ra (dB) Specimen B1 B2 B3 Grain size C1 C2 C3 Table speed D1 D2 D3 Depth of cut A1 A2 A3 -43 -42 -41 -40 -39 -38 -37 S/N ratio for Fn (dB) Specimen B1 B2 B3 Grain size C1 C2 C3 Table speed D1 D2 D3 Depth of cut A1 A2 A3 -36 -35 -34 -33 -32 -31 -30 S/N ratio for Ft (dB) Specimen B1 B2 B3 Grain size C1 C2 C3 Table speed D1 D2 D3 Depth of cut Fig. 2 Effect of grinding parameters on grinding outcomes � � � � � � � � � � Fig. 3 Second-order response surface and contour plot for surface roughness 0.4 0.6 0.8 1.0 0.4 0.6 0.8 1.0 Predicted Surface roughness, Ra(µm) Measured surface roughness, Ra(µm) 40 80 120 160 200 40 80 120 160 200 Predicted normal force, Fn(N) Measured normal force, Fn(N) 20 40 60 80 20 40 60 80 Predicted tangential force,