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 re-sults show that Mg-7Li-2Al-1.5Sn alloys are mainly composed of α-Mg,β-Li,LiMgAl2,Mg2Sn and Li2MgSn phases.The yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the extruded al-loy at room temperature reach 250 MPa,324 MPa and 11.9％,respectively.A lot of Sn-rich precipitates(Mg2Sn and Li2MgSn)are precipitated during extrusion with an average size of～14 nm,which is ben-eficial to the grain refinement.Dynamic recrystallization occurs during hot deformation and the nano-precipitates 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.Mg-7Li-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 perfor-mance 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

International Joint Laboratory for Light Alloys(MOE),College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;National Engineering Research Center for Magnesium Alloys,Chongqing University,Chongqing 400044,China;State Key Laboratory of Mechanical Transmissions,College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Beijing Spacecrafts,Beijing 100090,China

材料科学技术（英文版）

[1]Gang Zhou;Yan Yang;Hanzhu Zhang;Faping Hu;Xueping Zhang;Chen Wen;Weidong Xie;Bin Jiang;Xiaodong Peng;Fusheng Pan-.Microstructure and strengthening mechanism of hot-extruded ultralight Mg-Li-Al-Sn alloys with high strength)[J].材料科学技术（英文版）,2022(08):186-196

LiMgAl2,Li2MgSn

Microstructure,strengthening,mechanism,hot,extruded,ultralight,alloys,high,Duplex,structured,7Li,2Al,5Sn,were,fabricated,their,was,investigated,prepared,by,casting,temperature,extrusion,ratio,microstructure,mechanical,properties,systematically,OM,TEM,tensile,tests,sults,show,that,mainly,composed,Mg2Sn,phases,yield,YS,ultimate,UTS,elongation,EL,room,reach,respectively,lot,rich,precipitates,precipitated,during,average,size,which,ben,eficial,refinement,Dynamic,recrystallization,occurs,deformation,nano,effectively,dynamic,recrystallized,DRXed,grains,Besides,residual,dislocations,existed,un,result,possess,excellent,good,thermal,stability,can,prevent,growth,improvement,perfor,mance

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