Extrusion of Magnesium-Zinc Based Alloys : Influence of alloying elements on the microstructure and mechanical properties of extruded Mg-Zn based alloys

In this work, the influence of the additions of Zn, Zr and Ce-Mischmetall on the casting, indirect extrusion processing, microstructural development and resulting mechanical properties of Mg and Mg-alloys were investigated. It was found that grain size of the cast alloys is controlled by a grain growth factor (Q) mechanism. Q predicts the grain size of the cast billet, a parameter which influenced strongly the deformation response of the alloy during extrusion. Zener-Hollomon parameter (Z) was determined using process variables. Z correlated alloy dependent deformation variables during extrusion with the resulting average recrystallised grain size. Texture measurements revealed a singular recrystallisation development. Obtained results show correlations between initial alloy conditions and process variables indicating that the resulting microstructure and mechanical properties can be estimated by an appropriate set-up of selected alloy compositions and process parameters. Most of these correlations were based on proved phenomenological assumptions, which make them reliable values of reference for additional research and development of Mg wrought alloys.