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Refinement and migrating behaviors in Al-Si hypereutectic alloys solidified under electromagnetic vibration

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Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 301-308页

作者： Jianbo YU zhongming ren Kan9 DENG Shanghai Enhanced Laboratory of Ferro-Metallurgy Shanghai University Shanghai 200072 China

The effects of electromagnetic vibration （EMV） on the refinement and migration of primary silicons in the A1-18 wt pct Si alloy were investigated systematically. It was found that EMV could effectively refine primary silicons. The equivalent diameter of primary silicon first decreases slowly with the current increasing from 1 A to 3 A, but then drops rapidly between 3 A and 10 A, next gradually decreases with increasing current intensity. When the EMV intensity was low, the primary silicons were agglomerated and expelled to the top of a sample, the segregation of silicon grains gradually decreased and the agglomerating phenomena disappeared with the increase of EMV intensity, and the star-like coarse primary silicons turned refined flake or square morphology. The refinement and migration of primary silicons depended on the Lorentz force, gravity and the effective viscous force.

关键词： High magnetic field Electromagnetic vibration HypereutecticAl-Si alloys Primary silicon Refinement Migrating

Effects of electromagnetic vibration on the structure and mechanical properties of Al-6%Si alloy during directional solidification

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Acta Metallurgica Sinica(English Letters) 2009年第1期22卷 35-39页

作者： Jianbo YU zhongming ren Weili ren Kang DENG Yunbo ZHONG Department of Materials Science and Engineering Shanghai University Shanghai 200072 China

The effects of electromagnetic vibration on the grain refinement in directional solid- ification were investigated. It was found that the electromagnetic vibration applied in the melt not only can refine grains remarkably but also can enhance both tensile strength and ductility values of Al-6%Si alloy. SEM graphs show that coarse dendrite structure was broken up into a somewhat globular structure, and the morphology of eutectic silicon was changed from flaky to fibrous under electromagnetic vibration treatment. The refine mechanism under electromagnetic vibration was discussed.

关键词： Electromagnetic vibration Grain refinement Directional solidification Mechanical property

Achievement of giant cryogenic refrigerant capacity in quinary rare-earths based high-entropy amorphous alloy

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Journal of Materials Science & Technology 2022年第7期102卷 66-71页

作者： Yikun Zhang Jian Zhu Shuo Li Jiang Wang zhongming ren State Key Laboratory of Advanced Special Steels&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China

Magnetic refrigeration(MR)by utilizing the magnetocaloric(MC)effect is recognized as one of the most potential promising solid state environmentally friendly and high efficiency alternative method to the well-used state-of-the-art gas compression cooling *** this work,a systematic investigation of quinary equi-atomic rare-earths(RE)based Er_(20) Ho_(20) Gd_(20) Ni_(20) Co_(20) high-entropy(HE)amorphous alloy in terms of the microstructure,magnetic and magnetocaloric(MC)properties have been *** Er_(20) Ho_(20) Gd_(20) Ni_(20) Co_(20) exhibits promising glass forming ability with an undercooled liquid region of 72 *** cryogenic MC performances can be found in wide temperature from∼25 and∼75 K,close to H_(2) and N_(2) liquefaction,*** from the largest magnetic entropy change(-S M)reaches 17.84 J/(kg K)with 0-7 T magnetic field change,corresponding refrigerant capacity(RC)attains a giant value of 1030 J/*** promising cryogenic MC performances together with the unique HE amorphous characterizations make the quinary Er_(20) Ho_(20) Gd_(20) Ni_(20) Co_(20) HE amorphous alloy attractive for cryogenic MR applications.

关键词： HE-amorphous ribbons Magnetocaloric performances Rare earths Magnetic properties Giant refrigerant capacity

Application of Synchrotron X-Ray Imaging and Diffraction in Additive Manufacturing:A Review

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Acta Metallurgica Sinica(English Letters) 2022年第1期35卷 25-48页

作者： Naying An Sansan Shuai Tao Hu Chaoyue Chen Jiang Wang zhongming ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai200444China

Additive manufacturing(AM)is a rapid prototyping technology based on the idea of discrete accumulation which off ers an advantage of economically fabricating a component with complex geometries in a rapid design-to-manufacture ***,various internal defects,such as balling,cracks,residual stress and porosity,are inevitably occurred during AM due to the complexity of laser/electron beam-powder interaction,rapid melting and solidification process,and microstructure *** existence of porosity defects can potentially deteriorate the mechanical properties of selective laser melting(SLM)components,such as material stiff ness,hardness,tensile strength,and fatigue resistance *** X-ray imaging and diffraction are important non-destructive means to elaborately characterize the internal defect characteristics and mechanical properties of AM *** paper presents a review on the application of synchrotron X-ray in identifying and verifying the quality and requirement of AM ***,microstructures and mechanical properties of printed components characterized by synchrotron X-ray imaging and diffraction are summarized in this ***,this paper also elaborates on the online characterization of the evolution of the microstructure during AM using synchrotron X-ray imaging,and introduces the method for measuring AM stress by X-ray diffraction(XRD).Finally,the future application of synchrotron X-ray characterization in the AM is prospected.

关键词： Additive manufacturing Synchrotron X-ray imaging X-ray diffraction Defect formation Mechanical properties Residual stress

ELECTROMAGNETIC CHARACTERISTICS OF LEVITATION MELTING WITH COLD CRUCIBLE

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中国有色金属学会会刊：英文版 1999年第2期9卷 183-188页

作者： Deng, Kang Zhou, Yueming ren, zhongming Gong, Tao Jiang, Guochang Shanghai Univ Shanghai China

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１ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｉｎｇｗｉｄｅｌｙｕｓｅｄｉｎｍｅｔａｌｕｒｇｙａｎｄｎｅｗｍａｔｅｒｉａｌｓｐｒｏｃｅｓｓｉｎｇ，ｔｈｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｌｅｖｉｔａｔｉｏｎｍｅｌｔｉｎｇｗｉｔｈｃｏｌｄｃｒｕｃｉｂｌｅｉｓａｖａｌｉｄ...

关键词： cold crucibleelectromagnetic inductionlevitation meltingnumerical simulation

Effect of the simultaneous application of a high static magnetic field and a low alternating current on grain structure and grain boundary of pure aluminum

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Journal of Materials Science & Technology 2018年第12期34卷 2431-2438页

作者： Chengshuai Li Shaodong Hu zhongming ren Yves Fautrelle Xi Li State Key Laboratory of Advanced Special Steels Shanghai University SIMAP-EPM-Madylam/G-INP/CNRS PHELMA

Effect of the simultaneous application of a high static magnetic field and a low alternating electric current on the solidification structure of pure aluminum has been investigated. Results show that the refinement of the solidification structure is enhanced by the electric current under a certain magnetic field. However,when the magnetic field intensity exceeds a certain value, the refinement is impaired under a certain electric current. The observation by electron backscattered diffraction(EBSD) shows the complex fields have led to the increase of the low angle boundaries with the refinement. Moreover, the application of the static gradient magnetic field is capable of modifying the distribution of the refined grains. The above results may be attributed to the formation of the cavities during the electromagnetic vibration process and the high magnetic field.

关键词： Complex fields High magnetic field Refinement Grain boundaries

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

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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

LATS refining ladle slag modifying with CaO-CaF_2

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Journal of University of Science and Technology Beijing 2007年第2期14卷 125-129页

作者： Hongming Wang Guirong Li zhongming ren Bo Li Xuejun Zhang Guomin Shi School of Materials Science and Engineering Jiangsu University Zhenjiang 212013 China Shanghai Enhanced Laboratory of Ferro-Metallurgy Shanghai University Shanghai 200072 China Stainless Steel Branch Baosteel Group Shanghai 200431 China

To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refining ladle slag. The effect of CaO-CaF2 on the melting point, viscosity, and desulfurizing capability of the ladle slag was investigated. The melting point of the unmodified ladle slag is 1439℃. When adding 20wt% CaO-CaF2, the melting point is decreased to 1327℃. At 1500℃. the viscosity of the unmodified ladle slag is 6.5 Pa.s, which can be decreased lower than 2 Pa.s by adding more than 10wt% CaO-CaF2. The experimental results of desulfu- rization of the melts show that the desulfurizing power of the ladle slag can be enhanced by adding CaO-CaF2.

关键词： LATS ladle refining slag melting point viscosity desulfurization

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

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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