A powder metallurgical process of preparing a sheet from a powder having an
intermetallic alloy composition such as an iron, nickel or titanium
aluminide. The sheet can be manufactured into electrical resistance
heating elements having improved room temperature ductility, electrical
resistivity, cyclic fatigue resistance, high temperature oxidation
resistance, low and high temperature strength, and/or resistance to high
temperature sagging. The iron aluminide has an entirely ferritic
microstructure which is free of austenite and can include, in weight %, 4
to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr
.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1%
B, .ltoreq.1% submicron oxide particles and/or electrically insulating or
electrically conductive covalent ceramic particles, .ltoreq.1% rare earth
metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified
metal sheet by consolidating a powder having an intermetallic alloy
composition such as by roll compaction, tape casting or plasma spraying,
forming a cold rolled sheet by cold rolling the non-densified metal sheet
so as to increase the density and reduce the thickness thereof and
annealing the cold rolled sheet. The powder can be a water, polymer or gas
atomized powder which is subjecting to sieving and/or blending with a
binder prior to the consolidation step. After the consolidation step, the
sheet can be partially sintered. The cold rolling and/or annealing steps
can be repeated to achieve the desired sheet thickness and properties. The
annealing can be carried out in a vacuum furnace with a vacuum or inert
atmosphere. During final annealing, the cold rolled sheet recrystallizes
to an average grain size of about 10 to 30 .mu.m. Final stress relief
annealing can be carried out in the B2 phase temperature range.