Journal of Crystal Growth 275 (2005) e1501–e1505 Directional solidification of refined Al–3.5 wt% Ni under natural convection and under a forced flow driven by a travelling magnetic field K. Zaı¨dat a,Ã , T. Ouled-Khachroum a , G. Vian a , C. Garnier a , N. Mangelinck-Noe¨l b , M.D. Dupouy a , R. Moreau a a EPM, ENSHMG, BP 95 , F-38402 Saint Martin d’Heres Cedex, France b L2MP, UMR 6137 CNRS—Universite´s d’Aix-Marseille, de Provence et de Toulon, Campus de Saint Je´roˆme, Service 142, F -13397 Marseille Cedex 20, France Available online 15 December 2004 Abstract A new Bridgman-type furnace has been designed and built. This furnace has two specific items: a device conceived to minimise any residual radial thermal gradient near the solid–liquid interface (induced by the difference in thermal conductivities between liquid and solid), and a travelling magnetic field to drive a forced flow in the liquid above the solidifying interface. We have already performed comparative experiments of directional solidification on refined and non-refined Al-based alloys, under natural convection and under forced flow, controlled by the travelling magnetic field. We will present some characteristics of this new furnace, and the preliminary results obtained by solidifying refined Al–3.5 wt% Ni, with and without the travelling magnetic field. r 2004 Elsevier B.V. All rights reserved. PACS: 07.05.Fb; 07.20.Hy; 81.05.Bx; 47.27.Te; 47.65.+a Keywords: A1. Dendrites; A1. Directional solidification; A1. Magnetic fields; A1. Stirring; A2. Bridgman technique; B1. Alloys 1. Introduction The dendritic microstructure is the most com- mon microstructure found during the elaboration of metals and their alloys. Dendrites can be columnar or equiaxed according to the elaboration conditions (heat gradient, pulling rate, and solute concentration for an alloy, presence or absence of inoculating particles). The control of their form and their distribution is of primary importance for the resulting materials properties. The determina- tion of the columnar to equiaxed transition (CET) criterion is of uppermost importance in many industrial castings and is still a subject under ARTICLE IN PRESS www.elsevier.com/locate/jcrysgro 0022-0248/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2004.11.182 Ã Corresponding author. Fax: +33 47682 5211. E-mail address: kader.zaidat@hmg.inpg.fr (K. Zaı¨dat). URL: http://epm.cnrs.fr, http://www.12mp.fr.