One-step synthesis and consolidation of nanophase iron aluminide

The simultaneous synthesis and densification of nanophase iron aluminide is investigated. Elemental nanophase reactants produced by mechanical activat ion were reacted by field activation with the simultaneous application of u niaxial pressure. The process was demonstrated in this work by the synthesi s of dense nanometric FeAl. Iron and aluminum powders were co-milled in a s pecially designed planetary mill to obtain nanometric reactants and to avoi d formation of any product phases. These powders were then subjected to hig h AC currents (1250-1500 A) and pressures in the range of 70-106 MPa. Under these conditions, a reaction was initiated and completed within a short pe riod of time (2.5-3.5 min). XRD and energy dispersive analyses showed the p roduct to be Fe0.515Al0.485. The relative density of the product ranged fro m 98.7% to 99.7 %. The crystallite size of the "FeAl" intermetallic was det ermined by XRD line-broadening analysis using the Williamson-Hall method. T he size ranged from 32 to 89 mn and showed a dependence on lattice directio n.