Rheo-Extrusion of AZ91D

Abstract

The process of a novel rheo-extrusion was investigated by the combination of theoretical analysis and experimental verification based on a prototype counter rotating twin screw extruder. The investigation on the viscosity variation of AZ91D slurry and heat exchange of the system during extrusion shows both extrusion temperature and speed can affect the temperature and viscosity of the slurry. Thus, a continuous mass flow can be established by setting proper processing parameters to prevent bridging phenomenon in the extrusion according to the analysis. A thermal strategy for continuous output was setup at the highest extrusion speed of the extruder after investigation. The feasibility of the process and thermal strategy was then demonstrated by extruding an AZ91D rod using rheo-extrusion method.

Critical assessment: Opportunities in developing semi-solid processing: Aluminium, magnesium, and high-temperature alloys

“…twin screw system for the generation of thixotropic structure by cooling of liquid alloy to semi-solid state with shearing and mixing suspension. [77][78][79] The effects of processing parameters on alloy microstructure and mechanical properties are not straightforward and are still being studied.…”