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Effect of Solute Contents of Al-Ni-Sr Alloy on Glass Forming Ability and Thermal Stability

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journal of Rare Earths 2004年第z2期22卷 73-77页

作者： Taek Soo Kim j K Lee h j Kim j C Bae Advanced Materials R&D Center Korea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea

Glass forming ability (GFA) and structural characterization of a new amorphous Al-Ni-Sr alloy melt spun were investigated on the theory of the factors for the glass formation. The GFA was varied with the ratio of Ni to Sr in detail and successful amorphous phase dispersed with 2 ～ 5 nm precipitates was prepared from Al-Ni5-Sr3. Thermal stability and crystallization behavior of the amorphous phase were determined by continuous and isothermal heating technique on DCS, resulting that the crystallization occurs by the growth of fcc Al nanocrystals on the preexistent nuclei.

关键词： glass formation crystallization Al base amorphous alloys rapid solidification

Mg-Al Alloys Manufactured by Casting and hot Working Process

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journal of Materials Science & Technology 2008年第1期24卷 96-98页

作者： j.M.Kim j.h.jun W.j.jung Department of Applied Materials Eng. Hanbat National University Daejeon 305-719 Korea Light Materials Team Korea Institute of Industrial Technology Incheon 406-800 Korea

Mechanical properties of Mg-Al based alloys at different fabrication state,namely as-cast,hot rolled,and annealed,were investigated to develop the alloys that are suitable for the casting/hot working ***- imental results indicated that the castability such as hot cracking resistance tends to improve with increasing the aluminum ***,the elongation at elevated temperatures was observed to decrease as the AI content increases,implying difficulties in hot forming.A small amount of Zr additions could significantly enhance the room temperature mechanical properties of hot-rolled Mg-6%Al-1%Zn *** tendency of remarkable grain coarsening at high temperatures was effectively reduced by the Zr *** analyses suggested that very fine Al-3Zr precipitates formed in the Zr-added alloy are responsible for the obtained results.

关键词： Magnesium Casting Forming Tensile properties

CO_2 laser-micro plasma arc hybrid welding for galvanized steel sheets

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 47-53页

作者： C.h.KIM Y.N.AhN j.h.KIM Advance Welding & joining Research Group Korea Institute of Industrial Technology Incheon 406-840 South Korea

A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.

关键词： galvanized steel CO2 laser micro plasma hybrid welding

Thrombogenicity of biodegradable metals

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Bioactive Materials 2024年第8期38卷 411-421页

作者： D.E.j.Anderson h.h.Le h.Vu j.johnson j.E.Aslan j.Goldman M.T.hinds Department of Biomedical Engineering Oregon Health&Science UniversityPortlandORUSA Knight Cardiovascular Institute Oregon Health&Science UniversityPortlandORUSA Department of Biomedical Engineering Michigan Technological UniversityHoughtonMIUSA

Biodegradable metals offer a promising means to ameliorate many of the long-term risks associated with vascular devices made of conventional biostable stent *** numerous biodegradable metal alloys have been developed and characterized in animal models,knowledge of their blood reactivity and thrombogenicity remains *** hemocompatibility is particularly valuable because current generation drug-eluting stents pose a significant long-term thrombosis *** this study,four pure metals,widely used as degradable base materials(Fe,Zn,Mg,and Mo),and three alloys commonly used in cardiovascular devices[NiTi,CoCr,and stainless steel(SS)]were *** work examined how each of these metals activate platelets,coagulation factors,and inflammation using in vitro hemocompatibility assays and a clinically relevant ex vivo non-human primate arteriovenous shunt *** found that while all metals promoted a downstream activation of platelets and coagulation in flowing whole blood,platelet and fibrin attachment to Mg was markedly ***,Fe and Mo trended toward higher platelet attachment and contact pathway ***,the results suggest that Mg may delay clot initiation,but not eliminate clot formation,indicating the importance of understanding thrombosis in Mg alloys that are currently being developed for clinical use as biodegradable stents.

关键词： Vascular stents Biodegradable metals Thrombosis Contact pathway Platelets

A PARAMETER-UNIFORM TAILORED FINITE POINT METhOD FOR SINGULARLY PERTURBED LINEAR ODE SYSTEMS＊

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journal of Computational Mathematics 2013年第4期31卷 422-438页

作者： houde han j.j.h. Miller Min Tang Department of Mathematical Sciences Tsinghua University Beijing 100084 China Department of Mathematics Trinity College Dublin 2 Ireland Key Laboratory of Scientific and Engineering Computing Department of Mathematics and Institute of Natural Sciences Shanghai Jiao Tong University Shanghai 200240 China

In scientific applications from plasma to chemical kinetics, a wide range of temporal scales can present in a system of differential equations. A major difficulty is encountered due to the stiffness of the system and it is required to develop fast numerical schemes that are able to access previously unattainable parameter regimes. In this work, we consider an initial-final value problem for a multi-scale singularly perturbed system of linear ordi- nary differential equations with discontinuous coefficients. We construct a tailored finite point method, which yields approximate solutions that converge in the maximum norm, uniformly with respect to the singular perturbation parameters, to the exact solution. A parameter-uniform error estimate in the maximum norm is also proved. The results of numerical experiments, that support the theoretical results, are reported.

关键词： Tailored finite point method Parameter uniform Singular perturbation ODEsystem.

Manipulation of Crawling Growth for the Formation of Sub-millimeter Long ZnO Nanowalls

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journal of Materials Science & Technology 2008年第4期24卷 589-593页

作者： h.j.FAN M.Zacharias Department of Earth Sciences University of Cambridge U.K. Faculty of Applied Science Albert-Ludwigs-University Freiburg Germany Formerly at： Max Planck Institute of Microstructure Physics Halle Germany

Vapor-phase growth of ZnO nanowires based on gold catalyst is usually accompanied with lateral crawling growth on the substrate surface. We present results from our systematic experiments where the growth temperature and catalyst size are controlled. The data corroborate that it is possible to obtain clean vertical nanowire arrays while avoiding the crawling growth. 0% the other hand, crawling growth can be manipulated to obtain root-interconnected nanowire arrays, which could be useful for certain applications. Our results also imply that the previously suggested growth mechanism for the wire-on-wall hybridstructure might be incorrect. Finally, we show the formation of sub-millimeter long, straight ZnO nanowalls by combining a gold-catalyzed epitaxial growth of vertical nanowires and their mergence due to a confined crawling growth. These unconventional nanostructures might have unique electric or optical transport properties.

关键词： Nanowire Nanowall ZnO Crawling growth

A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

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journal of Magnesium and Alloys 2021年第4期9卷 1311-1335页

作者： A.R.Eivani h.Vafaeenezhad h.R.jafarian j.Zhou School of metallurgy and materials engineering iran university of science and technology^nartnaktehraniran department of biomechanical engineering delft university of technologymekehveg 22628 cd delftthe netherlands

The faults in welding design and process every so often yield defective parts during friction stir welding(FSW).The development of numerical approaches including the finite element method(FEM)provides a way to draw a process paradigm before any physical *** is not practical to simulate all possible designs to identify the optimal FSW practice due to the inefficiency associated with concurrent modeling of material flow and heat dissipation throughout the *** study intends to develop a computational workflow based on the mesh-free FEM framework named smoothed particle hydrodynamics(SPh)which was integrated with adaptive neuro-fiizzy inference system(ANFIS)to evaluate the residual stress in the FSW *** integrated SPh and ANFIS methodology was established and the well-trained ANIS was then used to predict how the FSW process depends on its *** verify the SPh calculation,an itemized FSW case was performed on AZ91 Mg alloy and the induced residual stress was measured by ultrasonic *** suggested methodology can efficiently predict the residual stress distribution throughout friction stir welding of AZ91 alloy.

关键词： Friction stir welding(FSW) Smoothed particle hydrodynamics(SPh) Adaptive neuro-fuzzy inference system(ANFIS) Ultrasonic Residual stress

Observation of Rotational Bands in Neutron—Rich ^106Mo Nucleus

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Chinese Physics Letters 2002年第2期19卷 180-183页

作者：许瑞清 j.h.hamilton DepartmentofPhysics TsinghuaUniversityBeijing100084 DepartmentofPhysics VanderbiltUniversityNashvilleTN37235USA

The rotational bands up to a spin of 16h in the neutron-rich ^106Mo nucleus have been investigated by measuring high-fold prompt γ-ray coincidence events following spontaneous fission of 252Cf with a Gammasphere detector array. The ground-state band, the one-phonon and two-phonon γ-vibrational bands, as well as a quasi-particle band have been confirmed and expanded. The other four collective rotational bands, three proposed as two-quasi-particle bands and one proposed as a β-vibrational band, have been newly observed. The characteristics of these collective bands and the possible configurations for the quasi-particle bands are discussed.

关键词： Gamma rays

^3PF2 neutron superfluidity in neutron stars and three-body force effect

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Chinese Physics B 2008年第9期17卷 3289-3293页

作者：崔常喜左维 h.j.Schulze Institute of Modern Physics Chinese Academy of Sciences INFN Sezione di Catania

We investigate the ^3PF2 neutron superfluidity in h-stable neutron star matter and neutron stars by using the BCS theory and the Brueckner-hartree-Fock approach. We adopt the Argonne V18 potential supplemented with a microscopic three-body force as the realistic nucleon-nucleon interaction. We have concentrated on studying the threebody force effect on the ^3PF2 neutron pairing gap. It is found that the three-body force effect is to enhance remarkably the ^3PF2 neutron superfluidity in neutron star matter and neutron stars.

关键词： ^3PF2 superfluidity neutron star three-body force Brueckner-hartree-Fock approach