Rheo-diecasting of magnesium alloys

A new semisolid metal processing technology, rheo-diecasting (RDC), has been developed for production of Mg-alloy components of high integrity. The RDC process innovatively combines the intensive forced convection provided by a twin-screw mechanism for the creation of high quality semisolid slurry and the high efficiency, low cost nature of the high pressure die casting (HPDC) process for component shaping. In this paper we present the RDC process and the resulting microstructures and mechanical properties of various Mg-alloys. It is found that the RDC process is capable of producing Mg-alloy samples with close-to-zero porosity and a fine, uniform microstructure throughout the entire casting irrespective of the section thickness. Compared with the existing processing techniques, the RDC process can produce high integrity components with substantially improved mechanical properties, which are suitable for demanding applications. In addition, the potential of using the RDC as an enabling technology for recycling Mg-alloy scrap and for manufacturing high integrity automotive components at industrial scale are also presented.