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Homogeneous Plastic Flow of Fully Amorphous and Partially Crystallized Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) Bulk Metallic Glass

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journal of Materials Science & Technology 2003年第6期19卷 557-560页

作者： q.WANG j.j.Blandin M.Suery B.Van de Moortele j.M.Pelletier GPM2 ENSPG D.U. B.P.46 38042 Grenoble France Institute of Materials Shanghai University Shanghai 200072 ChinaGPM2 ENSPG D.U. B.P.46 38042 Grenoble FranceGPM2 ENSPG D.U. B.P.46 38042 Grenoble FranceGEMPPM Bat. B. PascalINSA 69621 Villeurbanne Cedex FranceGEMPPM Bat. B. PascalINSA 69621 Villeurbanne Cedex France

The homogeneous plastic flow of fully amorphous and partially crystallized Zr(41.2)Ti(13.8)Cu(12.5)Ni(10)Be(22.5) bulk metallic glass (Vitl) has been investigated by compression tests at high temperatures in supercooled liquid region. Experimental results show that at sufficiently low strain rates, the supercooled liquid of the fully amorphous alloy reveals Newtonian flow with a linear relationship between the flow stress and strain rate. As the strain rate is increased, a transition from linear Newtonian to nonlinear flow is detected, which can be explained by the transition state theory. Over the entire strain rate interval investigated, however, only nonlinear flow is present in the partially crystallized alloy, and the flow stress for each strain rate is much higher. It is found that the strain rate-stress relationship for the partially crystaltized alloy at the given temperature of 646 K also obeys the sinh law derived from the transition state theory, similar to that of the initial homogeneous amorphous alloy. Thus, it is proposed that the flow behavior of the nanocrystalline/amorphous composite at 646 K is mainly controlled by the viscous flow of the remaining supercooled liquid.

关键词： Homogeneous plastic flow Zr41.2Ti13.8Cu12.5Ni10Be22.5 amorphous alloy,Partially crystallized amorphous alloy

Stochastic averaging of quasi integrable and resonant Hamiltonian systems excited by fractional Gaussian noise with Hurst index 1/2

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Acta Mechanica Solida Sinica 2017年第1期30卷 11-19页

作者： q.F.Lü M.L.Deng W.q.Zhu Department of Mechanics State Key Laboratory of Fluid Power and Mechatronic SystemsKey Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceZhejiang University

A stochastic averaging method of quasi integrable and resonant Hamiltonian systems under excitation of fractional Gaussian noise （fGn） with the Hurst index 1/2 〈 H 〈 1 is proposed. First, the definition and the basic property of fGn and related fractional Brownian motion （iBm） are briefly introduced. Then, the averaged fractional stochastic differential equations （SDEs） for the first integrals and combinations of angle variables of the associated Hamiltonian systems are derived. The stationary probability density and statistics of the original systems are then obtained approximately by simulating the averaged SDEs numerically. An example is worked out to illustrate the proposed stochastic averaging method. It is shown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of original system agree well.

关键词： quasi integrable and resonant Hamiltonian system Fractional Brownian motion Fractional Gaussian noise Stochastic averaging method Internal resonant

Recent development of chemically complex metallic glasses: from accelerated compositional design, additive manufacturing to novel applications

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Materials Futures 2022年第1期1卷 9-31页

作者： j Y Zhang Z q Zhou Z B Zhang M H Park q Yu Z Li j Ma A D Wang H G Huang M Song B S Guo q Wang Y Yang Department of Mechanical Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongPeople’s Republic of China Shenzhen Key Laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhenGuangdong 518060People’s Republic of China School of Materials Science and Engineering Dongguan University of TechnologyDongguanGuangdong 523808People’s Republic of China Institute of Materials China Academy of Engineering PhysicsJiangyouSichuan 621907People’s Republic of China State Key Laboratory of Powder Metallurgy Central South UniversityChangshaHunan 410083People’s Republic of China Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhouGuangdong 510632People’s Republic of China Institute of Materials Laboratory for MicrostructuresShanghai UniversityShanghai 200444People’s Republic of China Department of Materials Science and Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongPeople’s Republic of China Department of Advanced Design and System Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongPeople’s Republic of China

Metallic glasses(MGs)or amorphous alloys are an important engineering material that has a history of research of about 80–90 *** different fast cooling methods were developed for multi-component MGs between 1960s and 1980s,1990s witnessed a surge of research interest in the development of bulk metallic glasses(BGMs).Since then,one central theme of research in the metallic-glass community has been compositional design that aims to search for MGs with a better glass forming ability,a larger size and/or more interesting properties,which can hence meet the demands from more important *** this review article,we focus on the recent development of chemically complex MGs,such as high entropy MGs,with new tools that were not available or mature yet until recently,such as the state-of-the-art additive manufacturing technologies,high throughput materials design techniques and the methods for big data analyses(*** learning and artificial intelligence).We also discuss the recent use of MGs in a variety of novel and important applications,from personal healthcare,electric energy transfer to nuclear energy that plays a pivotal role in the battle against global warming.

关键词： metallic glasses amorphous alloys alloy design additive manufacturing machine learning high throughput materials design

Low working loss Si/4H-SiC heterojunction MOSFET with analysis of the gate-controlled tunneling effect

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journal of Electronic Science and Technology 2023年第4期21卷 35-47页

作者： Hang Chen you-Run Zhang State Key Laboratory of Electronic Thin Films and Integrated Devices School of Integrated Circuit Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu610054China

A silicon (Si)/silicon carbide (4H-SiC) heterojunction double-trench metal-oxide-semiconductor field effect transistor (MOSFET) (HDT-MOS) with the gate-controlled tunneling effect is proposed for the first time based on simulations. In this structure, the channel regions are made of Si to take advantage of its high channel mobility and carrier density. The voltage-withstanding region is made of 4H-SiC so that HDT-MOS has a high breakdown voltage (BV) similar to pure 4H-SiC double-trench MOSFETs (DT-MOSs). The gate-controlled tunneling effect indicates that the gate voltage (V_(G)) has a remarkable influence on the tunneling current of the heterojunction. The accumulation layer formed with positive VG can reduce the width of the Si/SiC heterointerface barrier, similar to the heavily doped region in an Ohmic contact. This narrower barrier is easier for electrons to tunnel through, resulting in a lower heterointerface resistance. Thus, with similar BV (approximately 1770 V), the specific on-state resistance (R_(ON-SP)) of HDT-MOS is reduced by 0.77 mΩ·cm^(2) compared with that of DT-MOS. The gate-to-drain charge (q_(GD)) and switching loss of HDT-MOS are 52.14% and 22.59% lower than those of DT-MOS, respectively, due to the lower gate platform voltage (V_(GP)) and the corresponding smaller variation (ΔV_(GP)). The figure of merit (q_(GD)×R_(ON-SP)) of HDT-MOS decreases by 61.25%. Moreover, the heterointerface charges can reduce RON-SP of HDT-MOS due to trap-assisted tunneling while the heterointerface traps show the opposite effect. Therefore, the HDT-MOS structure can significantly reduce the working loss of SiC MOSFET, leading to a lower temperature rise when the devices are applied in the system.

关键词： Heterojunction On-state resistance Silicon carbide(4H-SiC)trench metal-oxide-semiconductor field effect transistors(MOSFETs) Switching loss

Design and Pilot Programs of Marine Exposure Station of A Sea-crossing Bridge

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武汉理工大学学报 2010年第17期32卷 131-136页

作者： qIN M q WANG C j TU L q ZHANG G Z SUN T X Wuhan Harbour Engineering Design and Research Co. Ltd. Wuhan 430071China Key Lab of Large-span Bridge Construction Technology Ministry of CommunicationsWuhan 430071China Zhejiang Province Zhoushan Island Linking Construction Commanding Department Zhoushan 316032China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

This paper presents the Location,the structural design as well as the anti-corrosion and the pilot programs of the marine exposure station of Zhoushan Archipelago seas sea-crossing bridges. Subjected to the marine environment,the concrete structures in serve with different mixing proportions,cover thickness,additional anti-corrosion measures such as rust-preventing agent,coating,penetration crystalline waterproof material,silicone and permeable fabric were studied. Those results obtained provide important information for the maintenance of marine concrete and the structural design of sea-crossing bridges in the above sea area.

关键词： exposure station sea-crossing bridge marine concrete durability design

HEAT TREATMENT STRENGTHENING EFFECTS OF RARE EARTHS ON Mg-9Al ALLOY

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 8-14页

作者： Y.S.Wang j.Z.Yu q.D.Wang W.j.Ding Shanghai Automobile Accessory Co. Shanghai 200083 China Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

Mg-9Al-xRE magnesium alloys were studied, where, x is 0, 0.4. 0.8. 1.2 and 1.6% (in weight percent, wt%), respectively. Influence of rare earths (RE) on micro structure. and strength in both T4 (solute heat treatment) and T6 (solute heat treatment and artificial ageing treatment) were investigated. Strength of specimen was tested at ambient temperature. The micro structure was analyzed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction analysis. RE additions improved T4 tensile strength of the treated alloys. Small addition (0.4wt%) of RE greatly improved the strength of ageing treated (T6) Mg-9Al alloy, but further additions caused decreasing.

关键词： Mg-Al alloy rare earth (RE) heat treatment mechanical property strength

MICROWAVE PERMEABILITY SPECTRA OF SPUTTERED Fe-Co-B SOFT MAGNETIC THIN FILMS

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Acta Metallurgica Sinica(English Letters) 2008年第6期21卷 419-424页

作者： j.S. Liao Z.K. Feng j. qiu Y. q. Tong Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Permeability characteristics of sputtered soft magnetic Fe40Co40B20 thin films are investigated in the range of O. 5 to 5 GHz by a shortened microstrip transmission line perturbation method. Excellent microwave permeability is achieved at 0.4 Pa argon pressure： fr is 3.32 GHz, the real and imaginary part of permeability at 0.5 GHz are 104 and 61, respectively. In addition, the thickness effect on permeability is also studied. The minimum damping can be achieved at the thinnest film. Different sources contributed to in-plane anisotropy are discussed briefly. The deviation between the peak frequency of the imaginary part and the zero-crossing frequency of the real part of permeability is also presented.

关键词： Fe-Co-B In-plane anisotropy Magnetic thin films Permeability

STUDY ON THE SHOCK WAVE CRYSTALLIZATION OF AMORPHOUS ALLOYS BY DSC

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Acta Metallurgica Sinica(English Letters) 2002年第5期15卷 431-438页

作者： H. Y. Zhao, H. Wang, q.j. Liu, j.D. Kan and Z.q. LiuDepartment of Materials Science and Engineering, Yunnan University, Kunming 650091, China Dept. of Mat. Sci. and Eng. Yunnan Univ. Kunming 650091 China

Shock wave and annealing crystallization of amorphous alloys FeSiB, FeMoSiB and FeCuNbSiB were studied by isothermal and non-isothermal DSC technique. It was found that the shock wave crystallization is very perfect, the fraction crystallized is very close to 100%, though the period of crystallization is very short, only about 10-4-10-6s. Their produced phases differ from the parent phase in structure and composition. The high velocity of the transformation is very difficult to explain by the diffusion theory of solid state phase transition.

关键词： amorphous alloy nano-crystallization shock wave crystalliza-tion

A Special Kind of Interplanetary Coronal Mass Ejection

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Research in Astronomy and Astrophysics 2024年第12期24卷 185-193页

作者： H.q.Feng Y.Zhao G.q.Zhao H.B.Li L.Xiang j.M.Wang Institute of Space Physics Luoyang Normal University Henan Key Laboratory of Electromagnetic Transformation and Detection Luoyang Normal University

It is generally believed that coronal mass ejections(CMEs) have magnetic flux rope structures because of their helical shapes. However, only about 30%–40% of interplanetary CMEs(ICMEs) have a local magnetic flux rope structure. The usual explanations are that the spacecraft only crossed the flank of the ropes and failed to detect the complete magnetic flux rope structure or that some processes destroyed these magnetic flux rope structures. Several studies suggest that some ICMEs inherently possess disordered magnetic fields and consequently exhibit no magnetic flux-rope structures. We introduce a special kind of ICME which has a low magnetic field magnitude and stable magnetic field direction, relatively fast expansion speed, and lower proton temperature and density. All three of the measured magnetic field components are relatively stable. We want to know whether these ICMEs also have magnetic flux rope structures or not. We identified 20 special ICMEs and analyzed their evolution based on their observed characteristics. We took a special ICME as an example, which had an apparent rope configuration at 1 au but evolved to a special ICME at 5.4 au, to illustrate that this kind of ICME could come from magnetic clouds(MCs) whose rope structure had been being stretched due to expansion. We inferred that the missing obvious flux rope structure may be due to the expansion of MCs, not the flank crossing effect. However, more than 50% of the events were associated with the dominant x-component of the magnetic field, which indicates a leg ***, the detection of part of these special ICMEs may also be the result of the leg-crossing effect.

关键词： (Sun:) solar wind interplanetary medium Sun: coronal mass ejections (CMEs)