检索结果-南通市图书馆

In-situ observation of solid-liquid interface transition during directional solidification of Al-Zn alloy via X-ray imaging

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第4期39卷 113-123页

作者： Yuanhao Dong Sansan Shuai tianxiang zheng Jiawei Cao Chaoyue Chen Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The morphological instability of solid/liquid(S/L)interface during solidification will result in different patterns of *** this study,two dimension(2 D)and three dimension(3 D)in-situ observation of solid/liquid interfacial morphology transition in Al-Zn alloy during directional solidification were performed via X-ray *** a condition of increasing temperature gradient(G),the interface transition from dendritic pattern to cellular pattern,and then to planar growth with perturbation was *** effect of solidification parameter(the ratio of temperature gradient and growth velocity(v),G/v)on morphological instabilities was investigated and the experimental results were compared to classical"constitutional supercooling"*** results indicate that 2 D and 3 D evolution process of S/L interface morphology under the same thermal condition are *** seems that the S/L interface in 2 D observation is easier to achieve planar growth than that in 3 D,implying higher S/L interface stability in 2 D thin plate *** can be explained as the restricted liquid flow under 2 D solidification which is beneficial to S/L interface *** in-situ observation in present study can provide coherent dataset for microstructural formation investigation and related model validation during solidification.

关键词： Al-Zn alloy Directional solidification Solid/liquid interface instability In-situ observation X-ray imaging

6.5 wt%Si high silicon steel sheets prepared by composite electrodeposition in magnetic field

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第12期34卷 2492-2497页

作者： Minghu Peng Yunbo Zhong tianxiang zheng Lijun Fan Junfeng Zhou Weili Ren Zhongming Ren School of Materials Science and Engineering Key Laboratory of Advanced Metallurgy and Processing of Materials Shanghai UniversityShanghai 200072China

A new preparation method of near-net-shape 6.5 wt% Si high silicon steel sheets was proposed by combining composite electrodeposition(CED) and diffusion annealing under magnetic field. The obtained sheets were characterized by scanning electron microscopy, energy dispersive spectrometry, analytical balance and a silicon steel material measurement system. The results show that the surface morphology,the elemental distribution, the cathode current efficiency and the silicon content of coatings were obviously influenced by the micro and macro magnetohydrodynamics(MHD) flows under magnetic *** the effect of magnetic field, the silicon particles content of coatings showed an increasing trend and the diffusion process showed that an approximately uniform 6.5 wt% silicon steel sheet has been successfully obtained. The magnetism measurement showed that the high silicon steel sheet has the lower iron loss, and the iron loss further decreased under magnetic field. The new method proposed in this article,which is more environmentally friendly and low energy consumption, is feasible to prepare high silicon steel sheets.

关键词： High silicon steel Composite electrodeposition Diffusion annealing Magnetic field

Enhanced electrical,mechanical and tribological properties of Cu-Cr-Zr alloys by continuous extrusion forming and subsequent aging treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第15期110卷 187-197页

作者： Zhe Shen Zhongze Lin Peijian Shi Jiale Zhu tianxiang zheng Biao Ding Yifeng Guo Yunbo Zhong State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Shanghai Key Laboratory of Advanced Ferrometallurgy Shanghai UniversityShanghai 200444China

As a promising material for the new generation of high-speed railway contact wires,the comprehensive optimization of the electrical conductivity,strength,hardness and wear resistance of the Cu-Cr-Zr alloy has received extensive *** this paper,a high-performance Cu-1Cr-0.1Zr alloy with an ultimate tensile strength of 599.1 MPa,a uniform elongation of 8.6%,a microhardness of 195.7 HV_(0.2) and an electrical conductivity of 80.07%IACS was achieved by the continuous extrusion forming(CEF)and subsequent peak-aging *** grain refinement strengthening,dislocation strengthening and precipitation strengthening are identified to be responsible for the excellent electrical and mechanical properties of Cu-Cr-Zr *** wear behavior of Cu-Cr-Zr alloy was investigated by examining the evolution of worn surface morphology and subsurface *** microhardness(H)and reduced elastic modulus(E_(r))of the subsurface below the worn surface measured by nanoindentation were calculated to gage the tribological performance of Cu-Cr-Zr *** show that the continuously extruded and subsequently peak-aged specimen has the best wear resistance,which indicates that the tribological properties of CuCr-Zr alloy strongly depend on its strength and *** can be concluded that the CEF and subsequent aging treatment process provides a new and high-efficiency procedure for the continuous preparation of Cu-Cr-Zr alloys.

关键词： Cu-Cr-Zr alloy Continuous extrusion Electrical conductivity Mechanical properties Tribological properties

Inhibition of Cusp magnetic field on stray-crystal formation in platform region during directionally solidified single-crystal superalloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第11期106卷 183-194页

作者： Weili Ren Tao Zhou Xiaotan Yuan Ming Jian Congjiang Zhang Biao Ding Jianchao Peng tianxiang zheng Yunbo Zhong State Key Laboratory of Advanced Special Steel College of Materials Science and EngineeringShanghai UniversityShanghai 200444China China National South Aviation Industry Co. LtdZhuzhou 412000China Laboratory for Microstructures Shanghai UniversityShanghai 200444China

The stray crystal in the platform region is one of the common main defects in single-crystal superalloy blades. The simple and effective method to eliminate this defect is urgent to be explored. This work found that the Cusp magnetic field can effectively inhibit the stray-crystal formation in the platform. The tendency of stray-crystal formation decreases as the magnetic-field strength increases at a certain withdrawal rate and temperature-gradient. The suppressing effect decreases as the withdrawal rate or the temperature-gradient increases. Finally, the inhibiting mechanism on the stray-crystal formation from the Cusp magnetic field is proposed based on the experiments and the numerical simulation. The magneticfield application strengthens the flow velocity and changes the flow structure near the liquid-solid interface, and further reduces the radial temperature difference. Accordingly, the secondary dendrites in the heat-conduction undercooled zone expands towards the corner in a faster speed, which reduces the stray-crystal formation in the platform corner. This study provides an effective and simple method for decreasing the stray-crystal formation during the preparation of single-crystal with platform region.

关键词： Single-crystal superalloy Cusp magnetic field Stray crystals Platform region

Evolution of the microstructure and solute distribution of Sn-10wt% Bi alloys during electromagnetic field-assisted directional solidification

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第4期35卷 568-577页

作者： Zhe Shen Minghu Peng Dongsheng Zhu tianxiang zheng Yunbo Zhong Weili Ren Chuanjun Li Weidong Xuan Zhongming Ren State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering Shanghai University

The effects of forced flows at different velocities on microstructure and solute distribution during the directional solidification of Sn-10 wt% Bi alloys under a simultaneous imposition of a transverse static magnetic field(TSMF) and an external direct current(DC) have been investigated experimentally and numerically. The experimental results show that the solid-liquid interface will gradually become sloping with the increase of the forced flow velocity when the thermoelectric magnetic convection(TEMC)dominates the forced flow at solidification front. However, the interface will gradually become planar as the flow velocity further increases when the electromagnetic convection(EMC) dominates the forced flow. Moreover, when the flow velocity gradually increases, the primary dendrite spacing decreases from384 to 105 μm accordingly. The simulation results show that the solute distribution at the two sides of the sample can be significantly changed by the forced flow at solidification front. The rejected solute will be unidirectionally transported to one side of the sample along the TEMC(a low-velocity forced flow),thereby causing the formation of a sloping interface. However, the rejected solute will be returned back along the EMC(a higher-velocity force flow), which results in a planar interface. Furthermore, the solute content at the two sides of the sample under the forced flows at different velocities was measured. The results are in good agreement with the simulation results, which shows that the solute content difference between the two sides of the sample reaches the maximum when a 0.5 T TSMF is applied, while the solute content difference decreases to zero with a simultaneous application of a 0.5 T TSMF and a 1.6 × 10~5 A/m^2 external DC.

关键词： Directional solidification Sn-Bi alloy Forced flow Solute distribution Numerical simulation Electromagnetic field

Motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting:X-ray microtomography characterization and modeling verification

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第1期96卷 1-10页

作者： Yifeng Guo Zhibin Xia Qiang Li Mingyue Sun Weifeng Liu Shaogang Wang Zhe Shen tianxiang zheng Biao Ding Yunbo Zhong State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting(MC-ESR)process.A transient 2 D numerical model was also built to verify the experimental results and proposed *** number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF,while remained almost the same in electrode matrix and *** inclusions in LMF migrated from edge to mid region of LMF,accompanied with removal *** addition,the kinetic conditions for inclusion migrating to LMF/slag interface(LSI)were enhanced during MC-ESR process,thereby improving the inclusion removal efficiency in *** work highlights the 3 D characterization and motion/removal mechanisms of inclusions in electrode tip,as well as sheds new light on preparing high purity materials.

关键词： Inclusion motion Inclusion removal Electrode tip MC-ESR X-ray microtomography

Theoretical analysis of ultra-fast phase recovery in semiconductor optical amplifiers

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2012年第9期57卷 1078-1082页

作者： CHEN LiGong XU tianxiang zheng Xiu ZHANG ShangJian GUO XiaoWei TANG XiongGui LIU Yong School of Optoelectronic Information University of Electronic Science ＆ Technology of China Chengdu 610054 China

We present results from theoretical analysis of the phase dynamics in semiconductor optical amplifiers(SOAs).In particular,we focus on an aspect of the ultra-fast phase recovery that currently does not have adequate in-depth theoretical analysis and clear explanation of the physical *** build up a numerical model to analyze the ultra-fast phase recovery of semiconductor optical amplifiers in *** investigate the phase response characteristics,we analyze the different contributions to the phase shift,including intra-band effects such as carrier heating,spectral hole burning,and inter-band effects such as carrier *** addition,the impact of the pulses energy on phase shift is also *** on the analysis of phase response characteristics,we further explain the reason why a delay occurs between gain response and phase *** analysis results are in good agreement with the reported experimental *** results presented in this paper are useful for the SOA-based ultra-fast optical signal processing,such as optical switches,optical logic gates,and optical Add/Drop multiplexer.

关键词：半导体光放大器光分/插复用器动力学理论光信号处理物理机制数值模型响应特性载体加热

Nondestructive effect of the cusp magnetic field on the dendritic microstructure during the directional solidification of Nickel-based single crystal superalloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第3期62卷 52-59页

作者： Xiaotan Yuan Tao Zhou Weili Ren Jianchao Peng tianxiang zheng Long Hou Jianbo Yu Zhongming Ren Peter K.Liaw Yunbo Zhong State Key Laboratory of Advanced Special Steel College of Materials Science and EngineeringShanghai UniversityShanghai 200444China Laboratory for Microstructures Shanghai UniversityShanghai 200444China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

The mechanical-property improvement of directionally-solidified Nickel-based single crystal(SC)superalloy with the single-direction magnetic fields is limited by their destructiveness on the dendritic ***,the work present breaks through the *** shows that the application of the cusp magnetic field(CMF)ensures that the dendrites are not *** feature embodies that the primary dendrite trunks arrange regularly and orderly,as well the secondary dendrite arms grow *** contrast,both the unidirectional transverse and longitudinal magnetic field destroy the dendrite morphology,and there are a number of stray grains near the totally-re melted *** nondestructive effect is achieved mainly by the combined action of the thermoelectromagnetic force on the dendrites and thermoelectromagnetic convection in the melt during directional *** investigation should contribute a new route for dramatically and effectively improving the crystal quality and mechanical properties of the directionally-solidified alloys.

关键词： Dendrites Single-crystal superalloy Magnetic fields Directional solidification

Frequency-multiplexing photon-counting multi-beam LiDAR

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2019年第12期7卷 1381-1385页

作者： tianxiang zheng GUANGYUE SHEN ZHAOHUI LI LEI YANG HAIYAN ZHANG E WU GUANG WU State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

We report a frequency-multiplexing method for multi-beam photon-counting light detection and ranging(Li DAR),where only one single-pixel single-photon detector is employed to simultaneously detect the multibeam *** this frequency-multiplexing multi-beam Li DAR,each beam is from an independent laser source with different repetition rates and independent *** a result,the photon counts from different beams could be discriminated from each other due to the strong correlation between the laser pulses and their respective echo photons.A 16-beam Li DAR system was demonstrated in three-dimensional laser imaging with 16 pulsed laser diodes at 850 nm and one single-photon detector based on a Si-avalanche *** frequencymultiplexing method can greatly reduce the number of single-photon detectors in multi-beam Li DAR systems,which may be useful for low-cost and eye-safe Li DAR applications.

关键词： multiplexing laser beam