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Online since: July 2009
Authors: V.A. Krashaninin, Svetlana Oglezneva, Andrey N. Dmitriev, V.I. Bulanov
The obtained results will allow the reduction in the number of real experiments in the creation of new materials with required properties.
Development and usage of computer modeling allows the simplification and considerable speeding up of the technological processes, the reduction in the number of the real experiments and the saving of energy and material resources.
This is a result of the fact that the porosity, the developed interparticle surface, deficiency and structural activity of the powder nickel component increase considerably the role of diffusion processes which depend on mechanisms having small activation energy (surface, grain-boundary diffusion, diffusion along lattice defects).
At the sintering temperature 1250 °С values of concentration of molybdenum in the α-phase on the interphase boundary of the stabilised ferrite - intermetallic for the couple Fе-МоО3 exceeds the equilibrium concentration (35 % Мо instead of 21 %) and shows a considerable quantity of intermetallic inclusions and intermetallic grids on borders of grains in this zone.
This considerably reduces the number of real experiments and accelerates the working out of technological processes.
Online since: June 2022
Authors: Xueyuan Nie, Henry Hu, Su Feng Liu, N.C. Kar, Anita Hu
The presence of the Al3Fe needles results in a large number of defects in the form of transverse cracks.
Grain structure influenced by fast cooling.
The main parameter often employed to quantify the grain structure is the linear grain size, Dgr, which can be determined by the following equation: Dgr = L/n (10) where L is the secant length in mm or μm and n is the number of grains intersected by the secant.
The parameter d is measured similarly to the grain size Dgr .
The numbers on the micrographs represent the iron contents expressed in weight percent [39].
Online since: December 2012
Authors: Z.G. Hu, W.J. Dan, W.G. Zhang
Robertson et al. [4] predicted that cold rolling increased the number of strain reversals to failure at high cyclic strain amplitudes with no effect at low strain amplitudes.
Martensite formation varied with the composition, loading conditions, temperature and number of cycles.
Stolarz et al. [8] found that the grain size had a decisive influence on the amount of martensite formed and on the fatigue life which was almost twice longer in the fine microstructure with 20% alpha' than in the coarse one (2% alpha') with same plastic strain amplitude.
The volume fraction of austenite and the rate of phase transformation decrease while the number of cycles increases and the austenite fraction is almost constant after the number of cycles is more than 2000 times.
[8] Stolarz J., Baffie N., et al., Fatigue short crack behaviour in metastable austenitic stainless steels with different grain sizes.
Online since: June 2023
Authors: Andi Erwin E. Putra, Masbin Dahlan, Novriany Amaliyah, Azwar Hayat
The electrical conductivity, light transmittance, and roughness of the glass at one spray layer were 20 Ω/cm2, 87.1 %, and 0.010 µm respectively, and decrease along with the increase of the number of spray layers.
In this work, we tried to simplify the fabrication process of conductive glass via the spray deposition method by controlling the number of layers and analyzing the surface roughness and light transmittance.
The electrical conductivity value of conductive glass with the spray deposition method decrease along with the increase in the number of spray layer.
A reduced rate of light transmission as the number of layers increases indicates the presence of uneven grains or accumulation of solution grains on the surface of the substrate.
Online since: October 2016
Authors: Kazunari Yoshida, Vladimir Stefanov Hristov
A number of FEM analysis have confirmed that a balance between frictional and redundant work can be achieved through proper selection of the angle.
Drawing Stress σz ]MPa] Number of Passes Rt Fig. 6 Drawing Stress of Alternate Wire Drawing Drawing distance [mm] Fig. 5 Drawing limit of drawn wires for conventional drawing with: a) Tungsten Carbide Die b) Diamond Die; alternate drawing with: c) Tungsten Carbide Die d) Diamond Die Wire Drawing of Magnesium Alloys.
Ten points were tested from the surface of the wire being number 1 and point 10 being the centre of the wire.
In Fig. 9, the overall orientation of the metallic grains for the mother wire, conventionally drawn wire and alternately drawn wire can be examined.
Leading to believe that conventional drawing retains higher hardness near the surface, because withsmaller metallic grains, the hardness increases and ductility is reduced.
Online since: September 2013
Authors: Keya Dharamvir, Sumali Bansal
Despite the nobility of bulk gold [5], when the diameter of a gold particle goes below 5 nm, it becomes very active warranting an increasingly large number of applications.
This is done successively for all the 3N0α coordinates (N0 α = total number of atoms in the given sheet); and such a cycle is repeated several times till the energy of the sheet stabilized.
However, in the initial stages of deformation, at 10 – 40% elongation (Figs. 3a to 3d) formation of grain boundaries is seen.
Interestingly, with the very first picture (Fig. 3a) we see a lateral expansion of the sheet in order to accommodate the defects and the reoriented grains.
As the sheet is slowly stretched first isolated defects appear, then grain boundaries, followed by big holes before the sheet gets torn.
Online since: December 2013
Authors: Bo Tian, Rong Guo Hou, Hai Wen Liu, Sili Li
Table 1.Results of uniform design of coarse aggregate Serial number Coarse aggregate size[mm] and proportion[%] Natural accumulation No match vibration Match vibration 26.5-19 19-16 16-13.2 13.2-9.5 9.5-4.75 X1 X2 X3 X4 X5 VCA[%] VCA[%] VCA[%] 2 44.70 8.80 7.10 1.20 38.20 37.806 35.566 28.525 4 31.60 31.50 13.40 2.20 21.30 39.098 37.208 31.390 6 23.40 6.10 48.90 3.40 18.20 38.151 36.468 29.377 8 17.30 24.80 4.70 11.60 41.60 37.907 36.013 27.901 14 4.20 52.30 0.70 17.40 25.40 38.010 36.981 30.571 16 0.80 10.30 17.00 33.70 38.20 37.872 36.841 30.337 To verify the correlation on VCA with the compactness of concrete under vibration liquefaction and vibration liquefaction time, the grey system theory is introduced.
According to the size of the VCA, Modified Vebe Vibration Liquefaction Test, the different coarse aggregate gradation composition in uniform design is selected as follows (Table 1): the first group is number 2, 8 and 16 respectively, the second group is number 4, 6 and 14 respectively.
Table 2.Different range of coarse aggregate grain-size content Coarse aggregate's grain-size[mm] 31.5-26.5 26.5-19 19-16 16-13.2 13.2-9.5 9.5-4.75 4.75-2.36 Particle diameter Ranges[%] 0 12~8 28.5~18.5 13.5~3.5 26~30 25~35 0 Fine Aggregate Composition In accordance with the principle of interlocking-dense, fine aggregate is mainly used to fill the space of coarse aggregate skeleton, and should not have larger interference effect for it.
Table 3.The matching of different fineness modulus of sand Fineness modulus Content percentage[%] of different sand grain-size[mm] 4.75>r>2.36 2.36>r>1.18 1.18>r>0.6 0.6>r>0.3 0.3>r>0.15 0.15<r 3.1 24 20 13 33 4 6 2.9 20 18 14 33 9 6 2.7 18 15 14 32 15 6 2.6 15 14 15 34 16 6 2.5 12 12 20 33 17 6 2.3 9 9 18 38 20 6 2.0 6 6 15 33 34 6 As shown in Fig 8, by comparing the values of the concrete surface displacement after vibration roller and the speed of concrete surface displacement increased until it reaches steady state, as well as to evaluate the void structure of the concrete lateral surface after vibration liquefaction, can be concluded that sand is belongs to medium sand and is obviously better than that of the coarse sand and fine sand based on the characteristics of vibration liquefaction of RCC.
Niu, Influences of Coarse Aggregate Grain Sizes on Construction Performance & Pavement Quality of Pavement Roller compacted Cement Concrete, Journal of Highway and Transportation Research and Development, 1 (1999)
Online since: February 2018
Authors: Jian Yuan Wang, Hui Xing, Xiang Lei Dong, Ke Xin Jin
After analyzing the evolution of the tip radius ρ of the tilted dendrite with the variation of the pulling velocity and Péclet number, we found that ρ decreases as the pulling velocity is increased for a given Péclet number while it decreases with the Péclet number increasing for a given pulling velocity, as shown in Figure 10.
Mechanism of competitive grain growth in directional solidification of a nickel-base superalloy.
Phase-field study of competitive dendritic growth of converging grains duringdirectional solidification.
Growth competition of columnar dendritic grains: A phase-field study.
A coupled Cellular Automaton–Lattice Boltzmann model for grain structure simulation during additive manufacturing.
Online since: May 2012
Authors: Zhong Ping Yao, Zhao Hua Jiang, Chun Xiang Li
It is apparent that the Ti 2p photoelectron positions of all the CdS/TiO2 films almost keep the same as the number of inner CdS layer increased.
This diameter variation can be understood by considering the number of crystal nucleus during the thermal treatment process.
Compare the films without TiO2 layers, adding two TiO2 layers in CdS films are in favor of increasing the number of crystal nucleus (CdS and TiO2).
Although coherent grain size is smaller than 100 nm, bigger clusters formed by the coalescence of grains on the surface of the 10CdS/TiO2 film are observed.
The explanation of grain size variety by introducing TiO2 or CdS layer is described above.
Online since: November 2005
Authors: Yves Bréchet, Gary R. Purdy, Christopher R. Hutchinson, S.V. Subramanian, Hatem Zurob, G. Zhu
(1) where X is the recrystallized fraction, N is the number of recrystallization nuclei, M and F are, respectively, the grain boundary mobility and the driving force for recrystallization.
Solute additions hamper recrystallization by reducing the mobility of the recrystallizing grain-boundaries.
(2b) Because the interparticle spacing is determined by the number of particles, the probability term is strongly dependent on the precipitate number density and not on the volume fraction.
(b) Precipitate particles also exert a pinning (Zener) force on moving grain-boundaries [8].
(b) Precipitate particles exert Zener pinning force on moving grain boundaries.
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