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

Abstract

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 Al 2 Ca 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. The concurrent improvement in strength and ductility of the Mg-1Al-0.3Ca alloy is attributed to precipitation strengthening, dislocation strengthening and the formation of weak RD-split texture. • Ca-alloying refines the grain structures and is beneficial for the formation of densely dispersed Al 2 Ca particles. • The appropriate Ca/Al ratio induces high-density nano-sized Al 2 Ca particles and weakens the texture. • The annealed Mg–1Al-0.3Ca alloy achieves a simultaneous improvement in strength and ductility. • The underlying strengthening mechanisms influenced by the Ca/Al ratio are elucidated.

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