Twin-screw rheomoulding of AZ91D Mg-alloys

Abstract

Twin-screw rheomoulding is a new semisolid process for the near net shape production of metal’s components. It includes the advantage combination in both die-casting and injection moulding. In this unique process, a liquid alloy is fed into a twin-screw extruder, where the alloy is intensively sheared and cooled into the interval of liquidus and solidus to produce semisolid slurry with fine primary particles of pre-determined volume fraction. The well-sheared semisolid slurry is then discharged into a shot cylinder and subsequently injected into a mould cavity for component shaping. This paper introduces the development of the prototype machine and the experimental work carried out with industrial AZ91D magnesium alloy. The operating characteristics of the newly developed machine, microstructures and mechanical properties of rheomoulded AZ91D magnesium alloy will be reported.