Spark plasma synthesis from mechanically activated powders: a versatile route for producing dense nanostructured iron aluminides S. Paris a,b, * , E. Gaffet b,c , F. Bernard a,c , Z.A. Munir d a LRRS––UMR 5613 CNRS, Universit e de Bourgogne, 9, Avenue Alain Savary BP 47870, 21078 Dijon Cedex, France b Nanomaterials group, UMR 5060 CNRS/UTBM, F90010 Belfort, France c GFA––GDR 2391 CNRS, BP47870, F21078 Dijon Cedex, France d Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA Received 26 June 2003; received in revised form 23 September 2003; accepted 7 November 2003 Abstract The possibility of mechanically activated spark plasma sintering (MASPS) to perform simultaneously within a very short period of time the synthesis and the consolidation of nanophase iron aluminide from mechanically activated powders of Fe and Al in two different ratio (Fe53 at.% and Fe60 at.%) were confirmed in this work. Ó 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Iron aluminide; Mechanical milling; Self-propagating high-temperature synthesis; Powder consolidation; Nanocrystalline microstructure 1. Introduction Iron aluminides are excellent candidates for elevated temperature application due to combination of their low cost, low density, advantageous properties in particular a high specific strength, specific modulus, and good corrosion resistance at elevated temperatures under oxidizing and sulfudizing atmospheres [1,2]. Thus, they are very attractive materials in the aerospace, aircraft and defense industry for applications as compressor blades and missile skins [3]. However, commercializa- tion of these intermetallics has been limited because of thelowductilityexhibitedatroomtemperature[4,5].An improvement of mechanical properties can be achieved by decreasing the grain size to the nanometer scale [6,7]. The lack of success of such and similar approaches is citedasthereasonforthedearthofdataonthebehavior of bulk nanostructured materials [8,9]. Conventional methods of processing iron aluminides, including cast- ing, hot rolling and powder metallurgy, have been investigated [10,11]. However, none of these methods yield nanostructures. Four decades ago, high energy ball milling and mechanical alloying of powder mixtures, were reported to be efficient techniques for the preparation of nano- crystalline metals and alloys. However, in such a case, it is necessary to add a consolidation step to obtain a fully dense material. Different processes have been developed to consolidate nanoparticles [12,13]. Indeed, the full benefit of such nanostructured materials may be pre- served only if the consolidation process can eliminate extensive grain growth which is crucial for possible applications of nanophase materials. Prior work aimed at accomplishing this goal involved the consolidation of nanopowders obtained by mechanical alloying process [14], in general. The con- solidation techniques best suited to retain nanoscale grain size while producing near theoretical density materials seem to be hot-pressing [13,15], hot electric discharge sintering [16,17] such as plasma activated sin- tering (PAS) [18], and spark plasma sintering (SPS) that usesmicroscopicelectricdischargesbetweentheparticles under pressure [19] where, by carefully controlling the * Corresponding author. Address: LRRS––UMR 5613 CNRS, Universit e de Bourgogne, 9, Avenue Alain Savary BP 47870, 21078 Dijon Cedex, France. Tel.: +33-3-80396170; fax: +33-3-80396167. E-mail addresses: sparis@u-bourgogne.fr (S. Paris), eric.gaffet@ utbm.fr(E.Gaffet),fbernard@u-bourgogne.fr(F.Bernard),zamunir@ ucdavis.edu (Z.A. Munir). 1359-6462/$ - see front matter Ó 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.scriptamat.2003.11.019 Scripta Materialia 50 (2004) 691–696 www.actamat-journals.com