Trace elements can have a significant effect on the processing and properti
es of aluminium alloys, including sintered alloys. As little as 0.07 wt% (1
00 ppm) lead, tin or indium promotes sintering in an Al-Zn-Mg-Cu alloy prod
uced from mixed elemental powders. This is a liquid phase sintering system
and thin liquid films form uniformly throughout the alloy in the presence o
f the trace elements, but liquid pools develop in their absence. Analytical
transmission electron microscopy indicates that the trace elements are con
fined to the interparticle and grain boundary regions. The sintering enhanc
ement is attributed to the segregation of the microalloying addition to the
liquid-vapour interface. Because the microalloying elements have a low sur
face tension, they lower the effective surface tension of the liquid. This
reduces the wetting angle and extends the spreading of the liquid through t
he matrix. An improvement in sintering results. (C) 2001 Acta Materialia In
c. Published by Elsevier Science Ltd. All rights reserved.