Exploring kink strengthening in WZ21 magnesium alloy via slow solidification and extrusion

The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered (LPSO) phases that improves strength and ductility with minimal amounts of alloying elements. Even better improvements are associated with the specific microstructure known as the Mille-Feuille (MF) structure that can occur in this alloy as well after proper heat treatment. This study systematically compares the traditional ingot metallurgy method with the Bridgman method (slow cooling), coupled with diverse heat treatments and extrusion process. Microscopic analyses reveal variations in the presence of LPSO phases, MF structure, and especially grain size, leading to divergent mechanical and corrosion properties. The Bridgman approach surprisingly stands out, ensuring superior mechanical properties due to kink and texture strengthening.