Mg-Nd-Gd-Zn-Zr-xY（x=0

1.4

2.2

3.4

%

mass fraction）alloy was melted and prepared by gas protection.The effects of yttrium addition on the as-cast microstructure

element distribution and mechanical properties of the alloy after heat treatment were analyzed by optical microscopy（OM）

scanning electron microscopy（SEM）and energy dispersive spectroscopy（EDS）.The results reveal that average grain size of Mg-2.7Nd-1.5Gd-0.4Zn-0.5Zr alloy is decreased from 56μm to 48μm with 3.38% yttrium addition

which indicates that yttrium can refine the microstructure of the alloy to some extent.The tensile strength

yield strength and hardness of the alloy can be improved along with the increase of yttrium after heat treatment as a result of the increase of enrichment element area at grain boundary.When yttrium addition reaches 1.4%

the elongation of the alloy reaches the maximum value.With the Y addition of 2.2%

the comprehensive mechanical properties of the alloy present desirable

where the tensile strength

yield strength and elongation of the alloy reach 327 MPa

184 MPa and 5.5%

respectively.