| 1 | Microstructure and strengthening mechanism of hot-extruded ultralight Mg-Li-Al-Sn alloys with high strength显示文摘Duplex-structured Mg-7Li-2Al-1.5Sn alloys with high strength were fabricated and their strengthening mechanism was investigated.The Mg-7Li-2Al-1.5Sn alloys were prepared by casting and extruded at the temperature of 533 K with an extrusion ratio of 25:1.The microstructure and mechanical properties of Mg-7Li-2Al-1.5Sn alloys were systematically investigated by OM,XRD,SEM,TEM,and tensile tests.The results show that Mg-7Li-2Al-1.5Sn alloys are mainly composed ofα-Mg,β-Li,LiMgAl_(2),Mg_(2)Sn and Li_(2)MgSn phases.The yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the extruded alloy at room temperature reach 250 MPa,324 MPa and 11.9%,respectively.A lot of Sn-rich precipitates(Mg_(2)Sn and Li_(2)MgSn)are precipitated during extrusion with an average size of∼14 nm,which is beneficial to the grain refinement.Dynamic recrystallization occurs during hot deformation and the nanoprecipitates effectively refine the dynamic recrystallized(DRXed)grains.Besides,the residual dislocations existed in DRXed and un-DRXed grains result in the dislocation strengthening in the extruded alloy.Mg7Li-2Al-1.5Sn alloys possess excellent high-temperature mechanical properties with the YS,UTS and EL of 200 MPa,237 MPa and 26.7%at 423 K,respectively.Sn-rich precipitates with good thermal stability can effectively prevent grain growth,which is good for the improvement of the high-temperature performance of Mg-Li-Al-Sn alloy. | Gang Zhou Yan Yang Hanzhu Zhang Faping Hu Xueping Zhang Chen Wen Weidong Xie Bin Jiang Xiaodong Peng Fusheng Pan | 2022 | Journal of Materials Science & Technology2022，，8： | 7 |
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