Microstructures and mechanical properties of as-cast

solution-treated and extruded novel Mg-6Gd-3Y-2Zn-0.5Zr magnesium alloy have been investigated by optical microscope（OM）

SEM（scanning electron microscope） and tensile testing.The results show that the as-cast microstructure of Mg-6Gd-3Y-2Zn-0.5Zr alloy consists of α-Mg matrix and the block-like long period stacking ordered structure（LPSO） phase distributed around α-Mg matrix.After solution treatment at 450 ℃ for 16 h

fine lamellar structure LPSO phases grows from grain boundaries to the interior of the grains.The distinct age hardening response in extruded Mg-6Gd-3Y-2Zn-0.5Zr alloy aged at 200 ℃ can not be observed

however

the extruded alloy exhibits high strength and ductility

and ultimate tensile strength（UTS）

yield tensile strength（YTS）and elongation reach 335 MPa and 276 MPa

17%

respectively.