High strength-ductility synergy Mg–5Al–1Mn-0.5Zn-xCa (x = 0.5, 1 and 2, in wt.%) alloys without rare earth elements were prepared by conventional extrusion at 360 °C with an extrusion ratio of 25:1. The microstructure evolution and mechanical properties of Mg–5Al–1Mn-0.5Zn-xCa alloys were investigated by OM, XRD, SEM, EBSD, TEM and tensile tests. The as-extruded alloys are almost fine equiaxed grains with dispersed particles (Al₂Ca, Al₈Mn_5, Mg₂Ca and nanoscale (Al, Mn)-rich precipitates). With the increase of Ca addition, the average grain size decreases, the fine particles increase and basal textures become stronger, which result that the strength of the extruded alloy increases gradually while the elongation decrease. As-extruded Mg–5Al–1Mn-0.5Zn–2Ca exhibits excellent comprehensive mechanical properties of the ultimate tensile stress (UTS) of 340 MPa and fracture elongation (FE) of 12.8% with fine grains (2.42 μm), strong basal texture, high density of precipitates and dislocations. The TEM results show that Ca and Zn are segregated at the grain boundaries and a large amount of dispersed second-phase particles existed in the Mg–5Al–1Mn-0.5Zn–2Ca alloy, which is beneficial to grain refinement. Besides, the activated nonbasal slips are beneficial to the ductility which result from the restriction of twinning in fine grains and high Schmid factor (SF) of nonbasal slips.

高强-延展协同 Mg-5Al-1Mn-0.5Zn-xCa (x = 0.5, 1 and 2, in wt.%) 无稀土元素通过常规挤压在360°C下制备，挤压比为25： 1. 通过OM、XRD、SEM、EBSD、TEM和拉伸试验研究了Mg-5Al-1Mn-0.5Zn-xCa合金的显微组织演变和力学性能。挤压态合金几乎是细小的等轴晶粒，具有分散的颗粒（Al ₂ Ca、Al ₈ Mn _5、 Mg ₂富含钙和纳米级（Al，Mn）的沉淀物）。随着Ca添加量的增加，平均晶粒尺寸减小，细颗粒增加，基部织构变强，导致挤压合金强度逐渐增加，延伸率降低。挤压态 Mg-5Al-1Mn-0.5Zn-2Ca 具有优异的综合力学性能，极限拉伸应力 (UTS) 为 340 MPa，断裂伸长率 (FE) 为 12.8%，晶粒细小 (2.42 μm)，基部织构强，高密度的析出物和位错。TEM结果表明，Ca和Zn在晶界偏析，Mg-5Al-1Mn-0.5Zn-2Ca合金中存在大量分散的第二相颗粒，有利于晶粒细化。除了，