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Variations in Wear Resistance of a Novel Triboalloy Pseudoelastic TiNi Alloy-with Respect to its Pseudoelasticity and Hardness

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Journal of Materials Science & Technology 2001年第1期17卷 45-46页

作者： D.Y.Li and X.Ma dep.. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6 dep. of Chem. Univ. of Alberta Edmonton Canada

It has recently been found that TiNt shape memory alloy has another attractive property; high resistance to wear. The wear resistance of this alloy benefits from its pseudoelasticity (PE). It has, however, been noticed that other mechanical properties also affect the wear resistance, especially the hardness. Research was conducted to investigate the correlation between the wear resistance and both the PE and hardness. It has been demonstrated that when the PE is high, lower hardness leads to higher wear resistance.

关键词： TiNi Variations in Wear Resistance of a Novel Triboalloy Pseudoelastic TiNi Alloy-with Respect to its Pseudoelasticity and Hardness

Synthesis and Characterization of Rare Earth Tesnary Complexes with Cinnamic Acid and O-Phenanthroline

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Journal of Rare Earths 2000年第4期18卷 318-320页

作者：赵永亮赵凤英 dep. of Chem. Inner Mongolia Univ. Hohhot 010019 China

Thirteen solid rare earth tesnary complexes with cinnamic acid C 6H 5CH=CHCOOH, HL and o phenanthroline (phen), RE(phen)L 3 were synthesized. Their IR absorption spectra, molar conductance, TG DTA, X ray power diffraction analysis and fluorescence spectra were studied. The results show that all coordination compounds are oxidized and decomposed around 400 ℃ to 540 ℃. They are all crystalline material. The fluorescence spectra indicate that the fluorescence emission intensity of Eu(phen)L 3 is the highest among them.

关键词： rare earths cinnamic acid o phenanthroline IR spectra fluorescence spectra

Influence of Solid Fraction on Gravity Segregation of Sn in A1-20Sn Alloy Casting

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Journal of Materials Science & Technology 2000年第6期16卷 577-580页

作者： Zhang, P. Du, Y.H. Zeng, D.B. Cui, J.Z. Ba, L.M. dep. of Mechanical Eng. Tsinghua Univ. Beijing 100084 China

The influence of solid fraction of Al-20Sn alloy mushy on gravity segregation of Sn in casting was studied . The relationship between solid fraction and the temperature of alloy mushy and that between solid fraction of alloy mushy and size of Sn particle in ingot were determined. The results show that the relationship between solid fraction and the temperature of alloy mushy was fs=1683-4.86t+0.003 5t2. The extent of gravity segregation of Sn in casting reduced gradually with the increase of solid fraction of alloy mushy. When solid fraction of alloy mushy was larger than 40%, the gravity segregation of Sn in casting could be removed basically, and the relationship between solid fraction of alloy mushy and size of Sn particle in ingot was s=-0.64fs+70.8.

关键词： Metal casting

CHANGES OF MEAN VELOCITY PROFILES IN THE WAVE-CURRENT COMBINED FLOW

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Journal of Hydrodynamics 2001年第1期13卷 47-53页

作者： Wu, Y.S. Lian, J.J. Zhang, Q.H. Qin, C.R. dep. of Hydraulic Eng. Tsinghua Univ. Beijing 100084 China

A mathematical model is developed to simulate the change in mean velocity for the coexistent case of waves and current. The experimental results of mean velocity profile in a wave-current flume show the following features: Eulerian mean current profile for following current is more uniformly distributed than the corresponding pure current case, whereas , the case of an opposing current leads to the more straight profile. This model is based on Eulerian mean framework, and motions of wave and current are solved simultaneously. The comparisons of numerical results and experimental data show that the mathematical model presented in this paper is reasonable and feasible.

关键词： Computer simulation Hydrodynamics Mathematical models Sediment transport

Synthesis of TiB2+TiC by mechanical alloying

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Transactions of Nonferrous Metals Society of China 2001年第1期11卷 135-137页

作者：赵昆渝朱心昆程抱昌林秋实张修庆陈铁力苏云生雍岐龙 dep. of Materials Kunming Univ. of Sci. and Technol. Kunming 650093 China

The process of the mechanical alloying reaction between B 4C and Ti during ball milling was studied by EPMA and X ray diffraction. It is revealed that the reaction of 3Ti+B 4C=2TiB 2+TiC can be induced by mechanical alloying within 90 min of ball milling. The XRD peaks of TiB 2+TiC are broadened with increasing ball milling time. [

关键词： TiC TiB 2 mechanical alloying

Mathematical Modeling of Metal Active Gas (MAG) Arc Welding

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Journal of Materials Science & Technology 2001年第1期17卷 167-168页

作者： Takayoshi Ohji Yoko Tsuji Fumikazu Miyasakn and Takeshi Yamamoto dep.rtment of Adaptive Machine Systems, Osaka University 2-l, Yamada-oka, Suita, Osaka, 565-0871, Japan dep. of Adaptive Machine Syst. Osaka Univ. Osaka 565-0871 Japan

In the present paper. a numerical model for MAG (metal active gas) arc welding of thin plate has been developed. In MAG arc welding, the electrode wire is melted and supplied into the molten pool intermittently. Accordingly, it is assumed on the modeling that the thermal energy enters the base-plates through two following mechanisms, i.e., direct heating from arc plasma and 'indirect' heating from the dep.sited metal. In the second part of the paper, MAG arc welding process is numerically-analyzed by using the model. and the calculated weld bead dimension and surface profile have been compared with the experimental MAG welds on steel plate. As the result. it is made clear that the model is capable of predicting the bead profile of thin-plate MAG arc welding, including weld bead with undercutting.

关键词： arc welding welding process surface profile numerical model molten pool thin plate arc plasma

VERIFICATION And COMPARISON OF FORMULAS FOR BED LOAD TRANSPORT

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Journal of Hydrodynamics 2001年第1期13卷 8-11页

作者： Wang, X.K. Li, D.X. Qu, Z.S. Wang, D.C. dep. of Hydraulic Eng. Tsinghua Univ. Beijing 100084 China

Several typical formulas for bed load transport are examined based on field data. It is concluded that the Einstein formula provides good estimates for the bed load transport rate while other ones predict much lower transport rates. The main reason for the under-prediction is that Dp, the effective diameter of particles, is too large as a representative diameter of the bed material for gravel streams with partially movable bed. Performance of these formulas can be significantly improved if D35 is adopted instead of Dp.

关键词： Loads (forces) Structural loads

Effects of Annealing on High-Magnetoresistance Tunnel Junctions Using Co_(75)Fe_(25) Ferromagnetic Electrodes

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Journal of Materials Science & Technology 2000年第6期16卷 549-553页

作者： Han, X.F. Miyazaki, T. dep. of Appl. Phys. Tokoku Univ. Sendai 980-8579 Japan

Tunnel junctions, Ta (5 nm)/Ni79/Fe21 (3 nm)/Cu (20 nm)/Ni79/Fe21 (3 nm)/Ir22/Mn78 (10 nm)/Co75/Fe25/ (4 nm)/Ni79/Fe21 (4 nm)/Ni79/Fe21/(20 nm)/Ta (5 nm) wherein d=1.3 and 0.8 nm, with small active area from 100×100 down to 3×3 μm2 were fabricated using a micro-fabrication technique. The optical lithography combined with Ar ion-beam etching and CF4 active etching was used to pattern the junction area. A thin barrier layer and a short plasma-oxidation time for Al-oxide layer were used in order to reduce the junction resistance and increase the TMR ratio. The optimum annealing temperature and time for the highest TMR obtained were investigated to be around 300°C for an hour in this work. TMR ratio, effective barrier height and width, and breakdown voltage of the junctions can be remarkably enhanced upon annealing. High TMR ratio of 49.7% at room temperature and 69.1% at 4.2 K were achieved. TMR ratio and resistances decrease with increasing dc bias voltage from 0 to 1000 mV or with increasing temperature from 4.2 K to room temperature.

关键词： TMR Ferromagnetic Electrodes

Molecular Dynamics Simulation for Grain Boundary Deformation under Tensile Loading Condition

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Journal of Materials Science & Technology 2001年第1期17卷 145-146页

作者： Kim, Y.S. Choi, D.Y. Won, S.Y. dep. of Mech. Eng. Kyungpook Natl. Univ. Kyungpook South Korea

MD (molecular dynamics) simulations have been performed to observe the behavior of a grain boundary in the α-Fe plate under 2-dimensional loading. In MD simulation, the acceleration of every molecule can be achieved from the potential energy and the force interaction between this molecule and other molecules , and the integration of the motion equation by using Verlet method gives the displacement of each molecule. Initially, four α-Fe rectangular plates having different misorientation angles of the grain boundary are modeled by using the Johnson potential and the Morse potential. The potential energy of the grain boundary system is compared with that of the perfect structure model. Also, the width of the grain boundary can be obtained by investigating the local potential energy distribution. The tensile loading for each grain boundary model is applied and the behavior of the grain boundary is studied. From this study it is clarified that in the case of using the Johnson potential, the obvious fracture mechanism occurs along the grain boundary, and in the case of using the Morse potential, the diffusion of the grain boundary appears instead of the grain boundary fracture.

关键词： Simulation Molecular Dynamics Simulation for Grain Boundary Deformation under Tensile Loading Condition