Synergistic enhancement of strength and ductility of wrought dilute Mg-Al-Ca alloys via modifying Ca/Al ratio

Dilute Mg-Al alloys have favorable formability but their strength is often constrained by the lack of second phase particles. In order to enhance the mechanical performance, strategies including Ca-alloying and adjusting the Ca/ Al ratio have proven to be effective by introducing and modifying precipitates. Here, Mg-Al-Ca alloys processed via extrusion, hot-rolling and subsequent annealing were examined, focusing on microstructures and mechanical properties. The results demonstrate that Ca addition leads to grain refinement and introduces densely dispersed nano-sized Al2Ca particles in annealed Mg-1Al-0.3Ca (wt.%) alloy, which inhibit recrystallization and result in texture weakening. Consequently, the annealed Mg-1Al-0.3Ca alloy demonstrates a yield strength of 206 MPa and an ultimate tensile strength of 252 MPa, while also achieving a notable elongation to fracture of 16.4%. The decrease of Ca/Al ratio promotes the formation of micron-sized second phase particles instead of nano-sized ones, resulting in a high degree of recrystallization and a retained basal texture of annealed Mg-2Al-0.3Ca alloy. This work provides a reference for optimizing the size and density of second phase particles to develop high-performance Mg-Al-Ca alloys.