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I. INTRODUCTION

DEVELOPMENT of economically viable and environmentally friendly processes toward the bulk production of functional materials requires serious attention to meet the growing industrial needs. Powder metallurgy offers a versatile process route toward the production of metallic alloys in powder form. If the constituent metal powders could be produced from the respective oxides in situ by reduction using a suitable gaseous reductant, the alloy formation could be achieved at fairly low temperatures resulting in finegrained alloy materials. The gas-solid reduction route provides an excellent alternative toward the bulk production of tailor-made materials in a large scale and the possibility of using green energy. The wide range of applicability of this process route has not been fully explored toward the synthesis of novel materials such as intermetallics. The present work is part of an overall effort in the Division of Metallurgy, KTH (Royal Institute of Technology, Stockholm, Sweden), toward the production of functional materials and is focused toward the synthesis of Fe2Mo intermetallics. Over the years, the ordinary practice to produce Fe-Mo alloy has been by casting or more recently as an alternative way by mechanical alloying;[1] though the latter was employed only in a small-scale production. The existence of Fe2Mo intermetallic phase has in itself been a point of controversy for the evaluation of the Fe-Mo phase diagram involving iron and molybdenum. Some investigators were unable to detect this phase during diffusion couple experiments[2,3] or during annealing compact powders.[4,5,6] However, the Fe2Mo phase has been partially detected by aging Fe-Mo alloys.[7–10] Sinha et al.[11] reviewed the controversial evidence concerning the formation of Fe2Mo. Their work indicates that the formation of the phase is very slow. To the present knowledge of the authors, production of Fe2Mo intermetallic compound through a powder metallurgy route has not been documented. Kuyama et al.[1] investigated the synthesis of Fe-Mo alloys by the mechanical alloying method. These authors obtained an amorphous phase in the composition range 30 to 50 at. pct Mo. The objective of the R. MORALES, Graduate Student, and DU. SICHEN and S. SEETHARAMAN, Professors, are with the Division of Metallurgy, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Contact e-mail: [email protected] I. ARVANITIDIS, Researcher, is with Swedish Rock Engineering Research, SE-10074 Stockholm, Sweden. Manuscript submitted November 6, 2001. METALLURGICAL AND MATERIALS TRANSACTIONS B

present work is to study the reduction kinetics of Fe2MoO4 by H2 and to explore the feasibility of gas-solid reaction as a means to produce Fe-Mo alloys. II. EXPERIMENTAL A. Materials The raw materials employed along with their purity levels and suppliers are listed in Table I. To produce Fe2MoO4, stoichiometric amounts of Fe, Fe2O3, and MoO3 powders, with molar ratios 4:1:3, were mixed thoroughly using an eccentric oscillator at 200 rpm for 1 hour. The mi