Optimization on microstructure, mechanical properties and damping capacities of duplex structured Mg–8Li–4Zn–1Mn alloys

Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated. The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed of α-Mg, β-Li, Mg–Li–Zn, and Mn phases. The microstructure of the test alloy is refined owing to dynamic recrystallization (DRX) during hot extrusion. After hot extrusion, the crushed precipitates are uniformly distributed in the test alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of as-extruded alloy reach 156 MPa, 208 MPa, and 32.3%, respectively, which are much better than that of as-cast alloy. Furthermore, the as-extruded and as-cast alloys both exhibit superior damping capacities, with the damping capacity ( Q^-1 ) of 0.030 and 0.033 at the strain amplitude of 2 × 10⁻³, respectively. The mechanical properties of the test alloy can be significantly improved by hot extrusion, whereas the damping capacities have no noticeable change, which indicates that the duplex-structured Mg–Li alloys with appropriate mechanical properties and damping properties can be obtained by alloying and hot extrusion.