Effects of solid solution treatment and hot extrusion on microstructure and mechanical properties of Mg-6Y-7RE-0.4Zr alloys at room temperature and high temperature were investigated by optical microscope （OM）

SEM （scanning electron microscope）

EDS （energy dispersive spectroscopy）

XRD （X-ray diffraction） and tensile testing.The results reveal that as-cast microstructure of the alloy is composed of α-Mg matrix

Mg24Y5 and Mg12RE phases.After solid solution treatment at 500 ℃ for 5 hours

Mg-Y phase is mostly dissolved into the matrix

while part of Mg-RE phase still exists at the intergranular.Plasticity of as-extruded alloy at room temperature is greatly improved

and tensile strength is increased from 156MPa to 260MPa

and yield strength reach 220MPa

showing apparent yield plateau

and elongation is increased from 0.5% to 7%.In condition of high temperature

mechanical properties of extruded alloy are equivalent to those of one at room temperature below 250℃

while strength is slightly decreased with great increase of elongation at 300℃

where tensile strength

yield strength and elongation reach 215MPa

164 MPa and 20.5%

respectively.