Freeform fabrication methods allow the direct formation of parts built laye
r by layer, under the control of a CAD drawing. Most of these methods form
parts in thermoplastic or thermoset polymers, but there would be many appli
cations for freeform fabrication of fully functional metal or ceramic parts
. We describe here the freeforming of sinterable aluminium alloys. In addit
ion, the building approach allows different materials to be positioned with
in a monolithic part for an optimal combination of properties. This is illu
strated here with the formation of an aluminium gear with a metal-matrix co
mposite wear surface. (C) 1999 Kluwer Academic Publishers.