A thermomechanical process to make iron aluminide (FeAl) sheet

An innovative combination of roll compaction, and thermomechanical processi ng allowed manufacture of FeAl alloy intermetallic sheets with 24 wt.% Al c ontent. Green sheets of FeAl were obtained by roll compaction of water atom ized FeAl powder with a polymeric binder. Roll compacted green sheets were de-bindered and partially sintered prior to cold rolling through tungsten c arbide rolls. Cold rolling decreased the thickness, reduced the level of po rosity and work-hardened the sheets. Several intermediate annealings at or above 1100 degrees C were found to be necessary to relieve the work hardeni ng stresses prior to rolling the sheets to a final thickness of 0.20 mm. Th e annealing temperatures were chosen to be at or above 1100 degrees C to al low concurrent sintering of FeAl necessary for the densification of FeAl sh eets. Thermomechanical processing of cold rolled sheets allowed commercial manufacture of FeAl intermetallic sheets without the necessity of hot rolli ng of a cast FeAl ingot. Fully dense sheets possess fine grain microstructu re with an average grain size of 20 mu m. The electrical resistivities of F eAl sheets can be varied from 140 to 155 mu Omega cm(-1), and the high resi stivities make them ideally suited for resistive heating applications. Mech anical propel-ties of FeAl sheets are comparable to the properties of hot e xtruded FeAl alloys. (C) 1998 Elsevier Science S.A. All rights resented.