Solid-Phase Processing of Mg–Al–Mn–Ca for High Strength and Ductility

While rare-earth Mg alloys have remarkable properties for high strength applications, lower cost alternatives are necessary for the widespread industry use of Mg. Ca added Mg alloys have shown promise as an alternative to rare-earth alloys. Ca-based precipitates can reduce basal texture, reduce casting porosity, and increase mechanical strength of cast components. However, the accumulation of Ca-based precipitates along inter-dendritic regions can severely limit ductility. Here, we apply two solid-phase processing techniques, friction stir processing and shear assisted processing and extrusion, to produce wrought microstructure sheet and extruded tubes from a cast Mg–Al–Mn–Ca alloy. Ductility of the alloy is enhanced by densification under the applied thermomechanical processing conditions, grain refinement, and refinement of (Al, Mg)–Ca-based precipitates. Solid-phase processing provides a low cost opportunity to improve the properties of cast Mg alloys and improve service life.