Development of Novel Mg-Al-Mn-Based Alloys with High-Strength and Ductility via Co-Addition of Ce and Ca

In this work, the novel Mg-Al-Mn-Ce-(Ca) alloy system has been developed, and large-scaled and thin-walled Mg alloy extruded profiles with an actual composition of Mg-8Al-0.57Mn-0.42Ce (AM80E), and Mg-8Al-0.57Mn-0.42Ce-0.31Ca (AM80EA) were successfully fabricated. The extruded AM80EA alloy profile exhibited a refined recrystallized grain structure (with an average size of ~6.96 μm) and high-density second phase. These abundant micro-nano precipitates effectively inhibited grain boundary migration during recrystallization, achieving obvious grain refinement and providing strong grain refinement strengthening effects. Concurrently, these high-density second-phase particles can also prevent dislocations from slipping. The fine-grain strengthening and second-phase strengthening contribute to the yield strength (YS) of ~174 MPa, the ultimate tensile strength (UTS) of ~309 MPa, and the elongation (EL) of ~13.7% of the AM80E alloy profile. Through the further addition of the Ca element, the AM80EA alloy achieves better comprehensive mechanical properties than the AM80E alloy, exhibiting a YS of ~193 MPa, UTS of ~346 MPa, and EL of ~16.5%. This study demonstrates that, through rational alloying design and extrusion process control, Mg-Al-Mn-Ce-(Ca)-based alloy profiles with excellent mechanical properties can be obtained. Relevant work would provide references for developing these cost-effective high-strength Mg alloy products and promote their industrial applications.