ABSTRACT

Magnesium metal is used for a range of applications, many of which are as additions to other metals. Magnesium-based alloys constitute about one third of magnesium metal usage. Within the magnesium alloys category, approximately 90% are processed by high-pressure die casting with the remainder processed by gravity casting or wrought processing such as rolling and extrusion. Both hot- and cold-chamber die casting processes are widely used for the high-pressure die cast alloys. The Mg-Al system is the basis of the most common magnesium alloys. Variations in the aluminium content create a range of strength and ductility combinations. Additional elements such as zinc, manganese, rare earth’s, strontium, silicon and calcium are sometimes included for control of corrosion, high-temperature properties and castability. The hot cracking / hot tearing aspect of castability can be especially sensitive to small changes in composition. Until recently magnesium die cast alloys have been used exclusively in the as cast condition; however, recently developed heat treatable alloy are expanding the performance envelope of magnesium components.