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Wang J.,Shanghai University | Wang J.,University of Manchester | Fautrelle Y.,SIMAP EPM Madylam | Ren Z.M.,Shanghai University | And 10 more authors.
Applied Physics Letters | Year: 2014

Thermoelectric magnetic (TEM) flows in melts, which are generated by TEM forces in liquids, were uncovered by the shape evolution of the planar solid/liquid interface during directional solidification. The solid/liquid interface developing from an initially tilted shape to a nearly flat one has been in situ and real-time observed by means of synchrotron X-ray radiography. The corresponding numerical 3D simulations and velocity measurements of flows in the melt confirm that TEM flows exist and respond to this interface shape change. This observation provides visible evidence for TEM flows in melt and their influence on the solid/liquid interface dynamics when directional solidification is conducted in a magnetic field. © 2014 AIP Publishing LLC. Source


Wang J.,Shanghai University | Zhong Y.B.,Shanghai University | Fautrelle Y.,SIMAP EPM Madylam | Zheng T.X.,Shanghai University | And 3 more authors.
Applied Physics A: Materials Science and Processing | Year: 2013

Magnetic in-situ quenching refers to fixing and quenching the sample at a static high magnetic field (SHMF) up to 18 T; it has been achieved by a specially designed facility. Zn-7wt%Bi and Zn-10wt%Bi hyper-monotectic melts were quenched under different magnetic flux densities to investigate the influence of SHMF on the liquid-liquid phase separation process in solidifying hyper-monotectic alloys. Because this separation is mainly caused by the growth of minority phase droplets (Bi droplets in the present study), and such growth is attributed to the diffusion of Bi element and the coalescence between the droplets, the influence of SHMF on the growth of Bi droplets was analyzed. Results show that the imposed SHMF prevented the formation of layered structure in the Zn-10wt%Bi alloy and refined the Bi particles in the Zn-7wt%Bi alloy, which indicates that the SHMF retarded the liquid-liquid phase separation during solidifying the hyper-monotectic alloys. Indeed, the two motions of droplets in determining the coalescence, Marangoni migration and Stocks sedimentation, were slowed down by the applied SHMF. Analytical estimations of the magnitude of such damping effect have been made and show that the 18 T SHMF could reduce the speed of Stokes sedimentation and Marangoni migration of the minority phase droplets by about 95.5 % and 62.4 %, respectively. © 2012 Springer-Verlag Berlin Heidelberg. Source


Li X.,Shanghai University | Ren Z.,Shanghai University | Fautrelle Y.,SIMAP EPM Madylam | Zhang Y.,French National Center for Scientific Research | Esling C.,French National Center for Scientific Research
Materials Letters | Year: 2010

Effect of a high magnetic field on the Al-Al2Cu eutectic growth has been investigated. It has been found that the application of the magnetic field has aligned the eutectic grains with the < 001>-crystal direction of the Al2Cu phase along the magnetic field. Moreover, it has been proved experimentally that the Al2Cu crystal owns the remarkable magnetocrystalline anisotropy. Therefore, the alignment of the Al-Al 2Cu eutectic under the magnetic field may be attributed to the orientation of the Al2Cu crystal. © 2010 Elsevier B.V. All rights reserved. Source


Li X.,Shanghai University | Ren Z.,Shanghai University | Cao G.,Shanghai University | Gagmoud A.,SIMAP EPM Madylam | Fautrelle Y.,SIMAP EPM Madylam
Materials Letters | Year: 2011

Effect of a uniform magnetic field on the solid/liquid interface curvature and macrosegregation in directionally solidified the Al-0.85 wt.% Cu alloy has been investigated. Results show that the interface curvature and macrosegregation increase to a maximum when B is about 0.1 T; and then decreases as B still increases. This is good agreement with the computed velocities of the thermoelectric magnetic convection. Above results reveal that the uniform magnetic field induces the new convection and further modifies the interface curvature and macrosegregation. © 2011 Elsevier B.V. All rights reserved. Source


Wang J.,Shanghai University | Ren Z.,Shanghai University | Fautrelle Y.,SIMAP EPM Madylam | Li X.,Shanghai University | And 10 more authors.
Journal of Materials Science | Year: 2013

Al-0.85wt%Cu and Al-2.5wt%Cu alloys were directionally solidified under different transverse magnetic field (TMF) intensities to investigate the influence of TMF on the liquid/solid interface shape with respect to the various length scales appearing (planar, cellular, and dendritic interfaces). Results show that planar and cellular interfaces tilt to one side and then level off with increasing TMF although the dendritic interface appears not to behave in this manner. In situ synchrotron X-ray imaging was applied during directional solidification of the Al-4wt%Cu alloy under a 0.08T TMF, revealing leveling of the initially sloped interface. Solute redistribution, caused by thermoelectric magnetic convection (TEMC), responds to the changes in the interface shape. Because different typical length scales should be used in estimating the velocity of TEMC for planar, cellular, and dendritic interfaces, the maximum velocity of the convection ahead of the interface is obtained under different TMF intensities; correspondingly, leveling of the interface's degree of slop varies with TMF. © 2012 Springer Science+Business Media, LLC. Source

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