THIXOCASTING COPPER-BASE ALLOYS.

This article describes a pilot plant scale system which utilizes the thixotropic nature of semi-solid rheocast copper alloy. The rheocast slurries are cast into small ingots and subsequently cut into appropriate ″charges″ for casting. The individual charges are then rapidly reheated to the semi-solid range and fed to a cold chamber die casting machine. The thixotropic nature of the slurry is such that the reheated charges behave as soft solids and retain their shape through this point in the process. The shearing which occurs at gate entry then reduces the viscosity of the slurry to a level at which it flows smoothly into the die. This system offers the inherent advantages of die casting semi-solid slurries as well as precise shot metering, elimination of holding furnaces, reduced die temperatures, and good potential for automation.