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ELECTRONIC STRUCTURE OF THE LaNi_(5-x)Ga_x INTERMETALLIC COMPOUNdS

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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 157-162页

作者： d. chen G.X. Li d.L. Zhang T. Gao department of Physics and Electronic Engineering Xinyang Normal University Xinyang 464000 China College of Science Qingdao Agriculture University Qingdao 266109 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

The equilibrium structures and electronic structure of LaNi5-xGax （x=0, 0.5, 1.0） compounds have been investigated by all-electron calculations. Based on the full geometry optimization, the densities of states and electron densities of LaNi5-xGax are plotted and analyzed. It is clear that the substitution of Ga at the Ni site leads to a progressive filling of the Ni-d bands, the ionic interaction between Ni and Ni, with Ga plays a dominant role in the stability of LaNi5-xGax compounds. The smaller the shift of EF toward higher energy region, the more stable the compounds will be. The increased contribution of the Ni-d-Ga-d interactions near EF and the low energy metal-gallium bonding bands indicate that the compounds become more stable. The results are compared with experimental data and discussed in light of previous studies.

关键词： FLAPW and GGA LaNi5-xGax Intermetallie compound Electronic structure

NUMERICAL SIMULATION OF ULTRASONIC NONdESTRUCTIVE TESTING FOR WELdS

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 38-42页

作者： H.d.chen Y.W.Wang J.Xue Welding Research Institute Xi'an Jiaotong University Xi'an 710049 ChinaWelding Research Institute Xi'an Jiaotong University Xi'an 710049 ChinaWelding Research Institute Xi'an Jiaotong University Xi'an 710049 China

A computer simulation technique for ultrasonic propagation is utilized for the simulation of ultrasonic nondestructive testing (NdT). In this paper, one goal of the simulation is to compute ultrasonic field radiated by arbitrary transducers into pieces under examination. The other simulates a testing experiment. The simulation approach is based on the model for the computation of the ultrasonic field in isotropic media radiated from actual NdT transducers. After the field is known, remaining to be modeled is the interaction between this field and the scatters (defect) and the echo structure. The model of beam-defect interaction is based on the Kirchhoff’s diffraction approximations theory applied to elastodynamics. We assumed that the incident wave fronts on the defect are plane in the case of a focused immersed transducer and material is isotropic and homogeneous. The simulating results demonstrate that the model in ultrasonic NdT of welds is practical in further research and useful in optimizing testi

关键词： ultrasonic testing modeling welds numerical simulation

Long-term temporal-spatial dynamics of marine coastal water quality in the Tolo Harbor,Hong Kong,China

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Journal of Environmental Sciences 2004年第1期16卷 161-166页

作者： XUFu-liu K.C.LAM R.W.dawson TAOShu Y.d.chen departmentofUrbanandEnvironmentalSciences＆MOELaboratoryforEarthSurfaceProcess PekingUniversityBeijing100871China departmentofGeographyandResourceManagement TheChineseUniversityofHongKongShatinNewTerritoriesHongKongChina

The long-term temporal and spatial dynamics of marine coastal water quality in Tolo Harbor, Hong Kong were explored. The Harbor is divided into three zones represented as Harbor, Buffer, and Channel Subzones. The time range for the study covers the period from the 1970s to the 1990s. The selected indicators for the comprehensive assessment of water quality consist of physical, chemical and biological aspects, including suspended solids(SS), Secchi disk depth(Sd), 5-day biochemical oxygen demand(BOd\-5), total nitrogen(TN), total phosphorus(TP), faecal coliform, chlorophyll-a(Chl-a), and the number of red tide occurrences. The results indicated the presence of obvious temporal and spatial trends with regard to changes in water quality. Spatially, water quality in the Channel Subzone is the best, while that in the Harbor Subzone is the worst. On a temporal basis, the average trend from bad to good was 1980s>1990s>1970s as indicated by most of the selected water quality indicators. Water quality during the late 1980s reached its worst level with the lowest Sd, the highest BOd\-5, TN, TP, Chl-a concentrations, and the number of red tide occurrences. These long-term temporal-spatial water quality trends were also found in other studies of the Tolo Harbor. The large quantity of pollutants produced as a result of increasing population, industrial and commercial actives, and urbanization and industrialization trends in both Shatin and Tai Po seem to be primarily responsible for the changes in marine coastal water quality.

关键词： temporal-spatial dynamics water quality indicators pollution load Tolo Harbor

different diffusion Behavior of Cu and Ni Undergoing Liquidesolid Electromigration

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Journal of Materials Science & Technology 2014年第12期30卷 1235-1242页

作者： M.L.Huang Z.J.Zhang H.T.Ma L.d.chen Electronic Packaging Materials Laboratory School of Materials Science & Engineering Dalian University of Technology IC Packaging department Xi'an Institute of Microelectronic Technology

The diffusion behavior of Cu and Ni atoms undergoing liquidesolid electromigration（L-S EM） was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from Ni3Sn4into（Cu,Ni）6Sn5and further into [（Cu,Ni）6Sn5t Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 *** electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,Ni）6Sn5and further into[（Cu,Ni）6Sn5t（Ni,Cu）3Sn4] at the anode Cu interface while that from initial Ni3Sn4into（Cu,Ni）6Sn5and further into（Ni,Cu）3Sn4at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.

关键词： Cu/Sn/Ni Electromigration Cross-solder interaction Interfacial reaction diffusion

THE ROLE OF HYdROGEN IN Er-IMPLANTEd a-SiO_x:H

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Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 87-90页

作者： C.Y. chen W.d. chen Y.Q. Wang J.J. Liang Z.G. Xu Inst. of Semiconduct. Chinese Acad. of Sci. Beijing 100083 P.O. Box 921 China

A systematic investigation of the role of hydrogen in hydrogenated amorphous substo-ichiometric silicon oxide films (a-SiO:H) implanted with erbium is presented. The experimental results show that Er3+ luminescence increases with annealing temperature up to 535℃ and then drop sharply. Our work suggests that hydrogen evolution during annealing below 535℃ results in a reduction of defects in the films, and hence an improved Er3+ emission.

关键词： photoluminescence hydrogen erbium

Heat Transfer and Hydrodynamic Investigations of a Baffled Slurry Bubble Column

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Journal of Thermal Science 1992年第3期1卷 178-183页

作者： S. C. Saxena Z. d. chen department of Chemical Engineering The University of Illinois at Chicago Box 4348 Chicago IL 60680 U.S.A.

Heat transfer and hydrodynamic investigations have been conducted in a 0.108 m internal diameter bubble column at ambient conditions. The column is equipped with seven 19mm diameter tubes arranged in an equilateral triangular pitch of 36.5 mm. A Monsanto synthetic heat transfer fluid, Therminol-66 having a viscosity of 39.8 cP at 303 K, is used as a liquid medium. Magnetite powders, average diameters 27.7 and 36.6 μm, in five concentrations up to 50 weight percent in the slurry, are used. As a gas phase, industrial grade nitrogen of purity 99.6 percent is employed. Gas holdup in different operating modes and regimes have been measured for the two- and three-phase systems over a superficial gas velocity range up to 0.20 m/s in the semi-batch mode. Heat transfer coefficients are measured at different tube locations in the bundle at different radial and vertical locations over a range of operating conditions. All these data are compared with the existing literature correlations and models. New correlations are proposed.

关键词： heat transfer coefficient gas-phase holdup slurry bubble column.

THE PREPARATION ANd CHARACTERISTICS STUdY OF TiN_xO_y SPECTRAL SELECTIVE ABSORBING FILM BY MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 385-388页

作者： d.chen H.Shen B.W.Wang H.Q.Wang MaterialandScienceEngineeringInstitute SouthChinaUniversityofTechnologyGuangzhou510641China EnergyEngineeringInstitute ZhongshanUniversityGuangzhou510275China／／GuangzhouInstituteofEnergyConversionTheChineseAcademyofSciencesGuangzhou510640China GuangzhouInstituteofEnergyConversion TheChineseAcademyofSciencesGuangzhou510640China SchoolofMechanismandAutomobile ShenyangInstituteofAeronauticalEngineeringShenyang110034China

Spectral selective absorbent film is a crucial factor for the solar heating devi ce. There are many kinds of spectral selective absorbing film made by different ways. TiNxOy thin film with excellent spectral selecting absobent property were successfully prepared by dC magnetron sputtering with Ar as working gas, N2 and O2 as reactive gas, 99.9% titanium as the target and is copper slice as the subs trate. In this article, the optical characteristics and microstructure of TiNxO y thin film were studied. Inputing O2 can decrease the reflection of the visible lights, and double layer film can get good absorption for solar energy.

关键词： spectrum selecting absorbent film TiNxOy magnetron sputtering

OPTICAL CHARACTERIZATION OF TiO_2 THIN FILM ON SILICON SUBSTRATE dEPOSITEd BY dC REACTIVE MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 194-198页

作者： H.Q.Wang H.Shen d.C.Ba B.W.Wang L.S.Wen d.chen SchoolofMechanismandAutomobile ShenyangInstituteofAeronauticalEngineeringShenyang110034Ghina／／MechanismandAeronauticalCollegeNortheasternUniversityShenyang110004China TheSchoolofPhysicsandEngineering ZhongshanUniversityGuangzhou510275Ghina MechanismandAeronauticalCollege NortheasternUniversityShenyang110004China GuangzhouInstimdeofEnergyConversion Guangzhou510070China InstituteofMetalResearch TheChineseAcademyofSciencesShenyang110016China MaterialandScienceEngineeringAcademy SouthChinaUniversityofTechnologyGuangzhou510641China

TiO2 thin film has attracted considerable attention in recent years, due to its different refractive index and transparency with amorphous and different crysta ls in the visible and near-infrared wavelength region, high dielectric constant, wide band gap, high wear resistance and stability, etc, for which make it being used in many fields. This paper aims to investigate the optical characterizatio n of thin film TiO2 on silicon wafer. The TiO2 thin films were prepared by dC re active magnetron sputtering process from Ti target. The reflectivity of the film s was measured by UV-3101PC, and the index of refraction (n) and extinction coef ficient (k) were measured by n & k Analyzer 1200.

关键词： optical characterization TiO2 thin film dC reactive magnetron sputtering n & k

RESEARCH ON THE FORMATION MECHANISM OF INTERNAL CRACK IN THE CONTINUOUS CASTING SLAB

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Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 35-39页

作者： G.W. Chang G.C. Jin S.Y. chen X.d. Yue department of Materials ＆ Chemical Engineering Liaoning Institute of Technology Jinzhou 121000 China

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.

关键词： continuous casting dendritic spacing internal crack