X.H.Song(Centre for Materials Research and Analysis
,
Wuhan University of Technology
,
Wuhan 430070
,
China Manuscript received 6 November 1995
,
in revised form 24 May 1996)
金属学报(英文版)
The theoretical calculation formulas for the plane strain fracture toughness of mode Ⅰand Ⅱcracks of ceramic materials are deduced in this paper by using the nonlocal elasticity theory and maximum tensile stress criterion The deduced formulas, which are independent of crack geometry,bear a relation to material parameters.It is shown through experiment that the theoretical value of fracture toughness is the lower limit of testing value. The theoretical calculation formulas for fracture toughness relate the macro-mechanical performance of materials with the micro-structural parameters and,therefore, are beneficial to fully understanding the physical mechanism of material rupture.
关键词:
:nonlocal elasticity theory
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null
,
null
材料科学技术（英文）
The fractal growth and form is considered by molecular dynamics and simulated using computer.
关键词:
Masaharu Yamaguchi and Haruyuki Inui(Department of Metal Science and Technology
,
Kyoto University
,
Sakyo-ku
,
Kyoto 606
,
Japan)
材料科学技术（英文）
In two-phase TiAl alloys, the lamellar structures are of special interest and importance since they are so common and persistent. not only under as-cast conditions but also after thermal treatment. However. the lamellar structures are still poor in ductility,although they are beneficial for toughness and high temperature strength. This article will review the recent progress made in understanding the basic mechanical properties of the γ and α2 phases which comprise the two-phase alloys in Iamellar form, and discuss how an improved balance of strength and ductillty in the lamellar form may be achieved
关键词:
LIU Hefa SUN Naizhen DAI Xueli REN He Zhenjiang Shipbuilding Institute
,
Zhenjiang
,
Jiangsu
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ChinaLI Lijun Shanghai
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Electrical Machinery Plant.Shanghai.China professor.Institute of Metallic Materials Research
,
Zhenjiang Shipbuilding Institute
,
Zhenjiang
,
Jiangsu 212003
,
China
金属学报(英文版)
Precipitation form of Zr in CuCoBeZr alloy during solidificotion.cooling and final aging,as well as its effect on the high temperature properties have been studied and discussed.Results show that during solidificotion and cooding.Zr precipitates as fine particle.Cu_3Zr,which pre- vents X-Cu grains from growing and provides more nuclei for CoBe and hence leads to finer primary CoBe.Fine Cu_3Zr partrticles also precipitate during aging. Because Co_3Zr is difficult to coalesce at high temperatures,the recrystallization temper- uture increases and the high temperature mechanical properties improve.
关键词:
CuCoBeZr alloy
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null
张康侯
贵金属
doi:10.3969/j.issn.1004-0676.2008.02.011
评述了1996～2007年国际上对含金三元合金系相图、相变的研究进展.1996年以来,在主要国际专业刊物上发表了30多个三元金合金系相图的部分等温截面或纵截面,采用实验方法研究相图的工作占了绝大部分.在所研究的上述三元金合金系中,Au-Sn基合金系有11个,Au-Ag基合金系有6个,Au-Cu和Au-Sb基合金系各有4个,Au-Mn和Au-Si基合金系各有2个.这些合金系目前涉及到的主要应用领域为:钎焊材料、电触头材料、电子材料、磁性材料、形状记忆合金材料、金属离子源材料和喷丝头材料等.含金三元合金系的研究反映了当前对新型金合金功能材料的需求动向, 对指导促进相关新合金材料的开发有重要意义.
关键词:
金属材料
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金合金
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三元合金系
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相图
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进展
Jun SHEN
,
Jianguo LI
,
Hengzhi FU
,
Junyi SU
材料科学技术（英文）
The relationship between melt shape, electromagnetic pressure and magnetic field is studied for electromagnetic confinement and shaping of plate-form part. The results of experimental observation and theoretical inference can be summarized as follows. As the melt thickness a is large enough, causing the ratio of plate thickness to current theoretic skin depth a/delta larger than 2.2, the electromagnetic pressure acting on melt can be simply expressed as P-m = B-2/2 mu, and the melt shape would be known only by measuring the distribution of magnetic flux density As a is small and makes the ratio a/delta less than 2.2, the melt shape and electromagnetic pressure for confining and shaping are determined not only by magnetic flux density B but also by melt thickness a, electromagnetic parameter mu gamma and current frequency f. In this paper, an equation used to calculate electromagnetic pressure acting on "thin plate-form melt" is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and melt thickness a, electromagnetic parameter mu gamma and current frequency f.
关键词:
Acta Physico-Chimica Sinica
Absorption and desorption of water vapour in alkyd and polyurethane varnish were studied by quartz crystal microbalance(QCM). The absorption and desorption kinetics curves were Fickian in nature when the relative humidity was higher than 30%, while the solubility followed Henry's law. The average diffusion coefficient D increases linearly with relative humidity. A residual amount of water(about 10% of the equilibrium absorption amount under the condition of RH 100%) was found to remain in the coatings after extended exposure to dry air. FTIR analysis showed that the molecular structure of the coatings changed before absorption and after desorption of water vapour. The results showed that the residual water reacted with the coating molecule and H-bond was formed between water molecule and the C = O group. A considerable part of water in the coatings may transport in a chain mode by replacement. The rate of forming H-bond is much faster than that of diffusion. When the relative humidity is higher than 30%, the concentration of the water in the coatings is sufficient to support the reaction; diffusion is the controlling step of the absorption process, so the kinetics is Fickian. When the RH is lower than 30%, the concentration of the water in the coatings is not sufficient to support the reaction; the reaction rate is lowered to the degree that it is comparable to the rate of diffusion, then the kinetics of the whole process begin to deviate from Fick's law.
关键词:
water vapour;organic coatings;diffusion;quartz crystal microbalance;(QCM);fourier transform infrared spectroscopy (FTIR)
Acta Physico-Chimica Sinica
The relationship bettween the existing form and inhibiting behavior of dolecylamine(DDA) on amorphous alloy has been studied by electrochemical measurement, physical test and scanning tunneling microscopy. The experiment shows that there is different relationship between the inhibition concentration and inhibition percentage in different concentration scale. In w(DDA)=10(-6) similar to 10(-4) concentration range, the inhibition percentage increased strongly with the inhibitor concentration but the increase tendency of inhibition percentage became gently in 10(-4) similar to 10(-3) concentration scale. The adsorption isotherm formula fitting result shows that a typical mono-molecular layer of DDA was adsorbed on amorphous alloy during 10(-6) similar to 10(-4) concentration scale, without any effect from the neighbor inhibitor molecule, but in 10(-4) similar to 10(-3) range the force between the nearing neighbor inhibitor molecule decided the adsorption form. The result from STM and conductivity test indicats that the micelle had been formed when the concentration approached w(DDA)=2.3x10(-5), the protection effect DDA was prevented because of the forming of micelle.
关键词:
dodecylamine;micelle;inhibiting mechanism
Pai-Shan Pa
材料科学技术（英文）
A reuse fabrication module using micro electroetching as a precision machining process with a new design of a slant-form tool to remove the defective indium-tin-oxide (ITO) nanostructure from the optical poly-ethyleneterephthalate (PET) surfaces of digital paper display is presented in current studies. The low yield of ITO thin film deposition is an important factor in optoelectronic semiconductor production. The adopted precision reuse process requires only a short period of time to remove the ITO nanostructure easily and cleanly, which is based on technical and economical considerations and is highly efficient. In the current experiment, a large inclined angle of the cathode and a small end radius of the anode take less time for the same amount of ITO removal. A higher feed rate of the optical PET diaphragm combines with enough electric power to drive fast micro electroetching. A small rotational diameter of the anode accompanied by a small width of the cathode corresponds to a higher removal rate for the ITO nanostructure. A pulsed direct current can improve the effect of dreg discharge and is advantageous to couple this current with the fast feed rate of the workpiece. This improvement is associated with an increase in current rating. High rotational speed of the slant-form tool can improve the effect of dregs discharge and is advantageous to associate with the fast feed rate of the workpiece (optical PET diaphragm).
关键词:
Reuse fabrication
