Yield behaviour of cold compacted composite powders

A triaxial test rig is used to study the axsymmetric cold compaction behavi our of powder composites comprising aluminium with silicon carbide reinforc ement, and lead shot with steel reinforcement. Under hydrostatic loading th e pressure-density response shows an increase in strength with increasing v olume fraction of reinforcement. For a given volume fraction of inclusions, the compaction pressure to achieve a given relative density increases with diminishing size of reinforcement. The yield surfaces are measured after i sostatic and closed-die compaction; it is found that the shape depends upon the deformation path. with greatest hardening along the loading direction. The effect of reinforcement on the overall shape of the yield surface is f ound to be minor. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Sci ence Ltd. All rights reserved.