Microstructure and mechanical properties of rheo-diecast (RDC) aluminium alloys

摘要

A new semisolid metal (SSM) processing technology, the rheo-diecasting (RDC) process, has been developed for manufacturing near-net shape components of high integrity directly from liquid Al-alloys. The RDC process innovatively combines the well-established twin-screw mechanism with the conventional cold chamber die casting process. In this paper we present the microstructure and mechanical properties of both the as-cast and heat-treated RDC Al-alloys. The results indicate that the in the as-cast condition, RDC samples have a fine and uniform microstructure throughout the entire sample and close-to-zero porosity. The RDC samples have improved tensile strength and ductility, and further heat treatment of the RDC Al-alloys, can substantially improve strength, with a slight sacrifice of ductility. Discussions will be made on the effects of intensive forced convection and the effects of the resulting microstructure.