The generation of Mg-Al-Zn alloys by semisolid state mixing of particulate precursors

Abstract A number of Mg–Al–Zn alloys with thixotropic microstructures were created by the semisolid mixing of AZ91D and AM60B mechanically comminuted precursors in the Thixomolding ® system. The microstructure formation was analyzed along with the role of structural constituents in controlling strength, ductility and the fracture behaviour of the created alloy. It was found that the inhomogeneity in the partition of alloying elements intensified with a reduction in the processing temperature and the liquid fraction was highly influenced by the alloy with the lower melting range. Tensile strength showed a strong correlation with corresponding elongations and was predominantly controlled by the solid particles’ content in the microstructure, with negligible influence derived from changes in the alloy’s chemistry. Although elongation was affected by both the solid content and the alloy’s chemical composition, a larger role was still exerted by the former. The contribution of individual precursors to the tensile properties of the created alloy depended on the processing temperature. While near to complete melting, both of them contributed almost equally; with a temperature reduction, the deviation from the rule of mixtures enlarged, and properties were increasingly influenced by the precursor with the lower melting range.