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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

Parametric instability of a liquid metal sessile drop under the action of low-frequency alternating magnetic fields

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Journal of Hydrodynamics 2013年第2期25卷 300-308页

作者：雷作胜郭加宏 FAUTRELLE Yves ERNST Roland ETAY Jacqueline 任忠鸣 Shanghai Key Laboratory of Modern Metallurgy and Materials Processing Shanghai University simap-epm Laboratory Grenoble Institute of Technology/CNRS UMR 5266 France Shanghai Institute of Applied Mathematics and Mechanics Shanghai University simap-epm Laboratory Grenoble Institute of Technology/CNRS UMR 5266France

A 2-D mathematical model is developed in order to simulate a parametric electromagnetic instability oscillation process of a liquid metal droplet under the action of low frequency magnetic field. The Arbitrary Lagrangian-Eulerian （ALE） method and weak form constraint boundary condition are introduced in this model for implementation of the surface tension and electromagnetic force on liquid droplet free surface. The results of the numerical calculations indicate the appearance of various regimes of oscillation. It is found that according to the magnetic field frequency various types of oscillation modes may be found. The oscillation is originated from an instability phenomenon. The stability diagram of liquid metal droplet in the parameter space of magnetic frequency and magnetic flux density is determined numerically. The diagram is very similar to that found in the so-called parametric instability.

关键词： sessile drop parametric instability low-frequency alternating magnetic fields numerical simulation

Innovative Inductive Cold Crucible Configurations With Improved Efficiency

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 669-672页

作者： DUMONT Mikael ERNST Roland GARNIER Christian HASAN Ghatfan PETITPAS Patrick simap-epm Laboratory Grenoble Institute of Technology

The inductive cold crucible is a very interesting tool for processing materials by magnetic field without pollution.It is more and more used in various areas like in aeronautic,photovoltaic,waste recycling industries and also for medical applications.As the cold cracible in its current state of art has a low energetic efficiency,the better comprehension of this process thanks to recently improved multiphysic modeling tools and experimental measurements gives some guidelines for experimenting new kinds of cold crucibles.These elements are presented in this paper, especially the numerical modeling and first tests operated on a'thin shaped cold crucible'which seems very promising concerning the efficiency improvement and also a better overheating of liquid charge.

关键词： inductive cold crucible levitation melting skull melting

Controlled moderative sulfidation-fabricated hierarchical heterogeneous nickel sulfides-based electrocatalyst with tripartite Mo doping for efficient oxygen evolution

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Journal of Energy Chemistry 2022年第5期31卷 780-788页

作者： Xing Yu Qingyun Lv Lulu She Long Hou Yves Fautrelle Zhongming Ren Guanghui Cao Xionggang Lu Xi Li State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200072China Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China simap-epm-Madylam/G-INP/CNRS PHELMABP 7538402 St Martin d’HeresCedexFrance

An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due to the synergistically enhanced kinetics on enriched active sites and reconfigured electronic band structure. Here this work introduces hierarchical heterostructures into a NiMo@NiS/MoS_(2)@Ni_(2)S_(2)/MoO_(x)(NiMoS) composite by one-pot controlled moderative sulfidation. The optimal solvent composition and addition of NaOH enable NiMoS to own loose and porous structures, smaller nanoparticle sizes, optimal phase composition and chemical states of elements, improving the OER activity of NiMoS. To achieve current densities of 50 and 100 mA cm^(-1), small overpotentials of 275 and 306 mV are required respectively, together with a minor Tafel slope of 58 mV dec^(-1), which outperforms most reported sulfide catalysts and IrO_(2). The synergistic effects in the hierarchical heterostructures expose more active sites,adjust the electronic band structure, and enable the fast charge transfer kinetics, which construct an optimized local coordination environment for high OER electrocatalytic activity. Furthermore, the hierarchical heterostructures suppress the distinct lowering of electrical conductivity and collapse of pristine structures resulted from the metal oxidation and synchronous S leaching during OER, yielding competitive catalytic stability.

关键词： OER electrocatalysts Controlled moderative sulfidation Hierarchical heterostructures Nickel sulfides Tripartite Mo doping

Columnar-to-Equiaxed Transition During Directional Solidification Under Strong Magnetic Field

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 1044-1047页

作者： LI Xi DU Da-fan Annie GAGNOUD Yves FAUTRELLE REN Zhong-ming Department of Material Science and Engineering Shanghai University simap-epm-Madylam/CNRS ENSHMG

Effects of strong magnetic fields on the columnar-to-equiaxed transition(CET) have been investigated experimentally.Experimental results show that the application of a strong magnetic field causes a dendrite fragmentation and then the CET.The thermoelectric magnetic force acting on cells/dendrites and equiaxed grains in the mushy zone has been studied numerically.Numerical results reveal that a torque is created on cells/dendrites and equiaxed grains and the value of the thermoelectric magnetic force increases as the magnetic field intensity increase.This torque breaks cells/dendrites and drives the rotation of equiaxed grains.As a consequence,the CET will occur during directional solidification under a strong magnetic field.This may initiate a new method to induce the CET via an applied strong magnetic field during directional solidification.

关键词： columnar-to-equiaxed transition strong magnetic field directional solidification

Nucleation kinetics of paramagnetic and diamagnetic metal melts under a high magnetic field

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Journal of Materials Science & Technology 2021年第14期73卷 165-170页

作者： Zhipeng Long Qiuyue Jiang Jiantao Wang Long Hou Xing Yu Yves Fautrelle Zhongming Ren Xi Li State Key Laboratory of Advanced Special Steels Shanghai UniversityShanghai200072China simap-epm-Madylam/G-INP/CNRS PHELMABP 75.38402St Martin d'Heres Cedex.France

The influence of a high magnetic field(HMF)on the nucleation kinetics of paramagnetic aluminum and diamagnetic zinc melts has been investigated by differential thermal analysis(DTA).It is found that the application of an HMF increases the undercooling of pure aluminum and pure zinc at the same heatingcooling rates.Moreover,the quantitative analysis of activation energy calculated from the DTA results using the Kissinger method manifests that the HMF reduces the activation energy of pure aluminum and pure zinc.Regardless of magnetism,the nucleation frequency under an HMF is higher than that without an HMF.Furthermore,the increase in undercooling under the HMF is mainly attributed to the increase of the contact angle,calculated by the functional relationship between the cooling rate and undercooling.This result is consistent with the increase of the calculated nucleation work for pure aluminum and pure zinc.Additionally,the increase in undercooling caused by the HMF is partly ascribed to the magnetic field-induced suppression of thermal convection in the undercooled melt.

关键词： Undercooling Activation energy Nucleation work High magnetic field

Effect of a High Magnetic Field on the Microstructure During Directionally Solidified Sn-20wt.%Pb Hypoeutectic Alloy

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 1116-1122页

作者： DU Da-fan LI Xi Yves FAUTRELLE REN Zhong-ming LU Zhen-yuan YU Qing-chen Department of Materials Engineering Shanghai University simap-epm-Madylam/CNRS Grenoble Institute of Technology

The microstructures of Sn-20wt.%Pb hypoeutectic alloy directionally solidified under a longitudinal magnetic field were investigated.The results show that the application of a high magnetic field has a great influence on the morphology of primary β-Sn phase at a temperature gradient of G_L=52 K/cm.At a certain growth speed,with the increase of magnetic field intensity,the magnetic field causes the primary β-Sn phase irregular and to be deformed,further,the magnetic field promotes the columnar to equaixed transition(CET).Further,the thermoelectric magnetic force(TEMF) imposed on the dendrite under a high magnetic field has been calculated and the results show that the numerical magnitude of the TEMF during directional solidification under a 10 T high magnetic field is about 10~4N/m^3 and this force should be responsible for the occurrence of the CET in the Sn-Pb alloy.This may act as an experimental proof that the coupling of temperature gradient and high magnetic field will induce the occurrence of the CET in Sn-Pb alloy.Above phenomena may be attributed to the thermoelectric magnetic force(TEMF)in solid.

关键词： high magnetic field Pb-Sn hypoeutectic alloy directional solidification columnar-to-equiaxed transition

Controlling and adjusting the concentration distribution during solidification process using static magnetic fields

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Journal of Materials Science & Technology 2020年第15期47卷 86-91页

作者： Pinfang Jiang Jiantao Wang Long Hou Yves Fautrelle Xi Li State Key Laboratory of Advanced Special Steels Shanghai UniversityShanghai200072PR China simap-epm-Madylam/G-INP/CNRS PHELMABP 7538402St Martin d'Heres CedexFrance

As concentration distribution changes have important effects on material structures and properties,controlling the concentration distribution is essential to alloy performance.The aim of the present work is to control and adjust the concentration distribution by the static magnetic field.It is found that the magnetic field disperses grain boundary segregation and causes the uniform distribution of concentration.Further,by the three-dimensional computed tomography(3 D-CT) reconstruction,the flow distribution is seen and the effect mechanism of the magnetic field is revealed.The present work may clarify the ambiguous understanding on the effect of the static magnetic field on solidification process.

关键词： Static magnetic feld Concentration distribution Structures

Study of the Electromagnetic Coupling in an Inductively Coupledplasma Torch at Atmospheric Pressure

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 695-699页

作者： B.Saadi J.Altenberend G.Chichignoud Y. Delannoy CNRS-simap-epm BP75 Saint Martin d'Hères Cedex 38402France

This work is devoted to study the behaviour of an inductively coupled plasma torch using argon,hydrogen and oxygen at atmospheric pressure.Thermal plasmas are generally used to form highly reactive species and to transfer enthalpy.Precise characterisation of the plasma behaviour is thus relevant to evaluate chemical and thermal effects of the plasma.For equivalent configurations in terms of torch geometry and gas flows,a transition between two different coupling modes is identified affecting atomic species distribution and energy transmitted to a copper target.These two modes are affected by total electrical power input and oxygen and hydrogen flow rates,showing up hysteresis behaviour. Electrical current and frequency progress are analysed to highlight the transition between the two coupling modes. Optical spectroscopy is used to measure temperature profiles and radial atomic oxygen concentration profiles for different coupling modes.We observe that-depending on the coupling mode-temperature profile,atomic species distribution as well as the power transmission to a copper target are affected.

关键词： inductively coupled plasma optical spectroscopy temperature field

Study of the Influence of Traveling Field Frequency and Wave Length on Pressure-Flow Rate Characteristic and Modeling of MHD Coupling in Annular Linear Induction Pump

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Journal of Iron and Steel Research(International) 2012年第S1期19卷 463-466页

作者： C.ROMAN M.DUMONT Y.FAUTRELLE V.FIRETEANU S.VITRY F.REY Grenoble Institute of Technology/simap/epm Laboratory France University POLITEHNICA of Bucharest EPM NM LaboratoryRomania CEA/Cad/DTN/STPA/LCIT CadaracheFrance

The paper studies specific pumping characteristics of the annular linear pumps with travelling field(ALIP)for liquid sodium.This research represents a preliminary step in the study and development of very large electromagnetic pumps able to provide high flow rates.Since in such cases the magnetic Reynolds number are quite large,it is necessary to take into account the full magnetohydrodynamic interaction between the electromagnetic field and the liquid metal flow inside the pumping channel.The case where the velocity field is uniform in the channel cross section is firstly considered. Then,the coupling between the electromagnetic aspects with the hydrodynamic ones in a 2D axisyrnmetric fmite element model is studied,in order to compare the magnetic convection and the magnetic diffusion.

关键词： electromagnetic pump traveling magnetic field magnetohydrodynamic coupling