Extrusion characteristics of aluminium alloy/SiCp metal matrix composites

Systematic extrusion studies have been carried out on aluminium alloy 2124/ SiCp metal matrix composites. Effects of various extrusion process paramete rs, such as die design, ram speed, extrusion ratio, reheat temperature, and lubrication, on the pressure requirement and surface quality of the as ext ruded circular rods have been investigated. Different volume fractions of S iC particles (10, 15, and 20 vol.-%) were used for the synthesis of metal m atrix composite billets. These composites were synthesised using two differ ent techniques, namely, stir casting and powder metallurgy. These billets w ere then hat extruded on a laboratory scale 500 ton vertical hydraulic pres s. The significance of specially designed dish shaped dies, avoiding the de ad metal zone, has also been highlighted. The results indicated that the be st extrusion was possible when powder metallurgical processed billets were extruded. Volume fraction analysis of ceramic reinforcement in the extruded rod (typically 2 m long) and in the extruded discard showed Ilo appreciabl e backward migration of these particles during extrusion.