The active rare earth element Y can easily transform to yttrium oxide inclusions during the melting and casting of magnesium alloys

resulting in the yield reduction of Y-containing magnesium alloy castings

which has become one of the key bottlenecks in the promotion and application of Y-containing magnesium alloys.The microstructure and mechanical properties of Mg-xGd-（12-x）Y-0.5Zn-0.5Zr（x=9

10

11

12）alloy were investigated with part of Y substituted for Gd under the premise of keeping the fixed total mass fraction of rare earths.The results indicate that the phase composition of the as-cast alloy is mainly composed ofα-Mg matrix and（Mg

Zn）

5

（Gd

Y）eutectic phase

and the second phase is almost completely dissolved after solution treatment

with the second phase particles of Mg5Gd

Mg3Gd or Mg2Gd remaining.Alloys containing Y element can reach the peak hardness at 16 h

while the Mg-12Gd-0.5Zn-0.5Zr alloy reaches the peak hardness at 64 h

which is significantly lower than that of the other alloys contained Y.In three states of as-cast

solid solution and peak aging

Mg-9Gd-3Y-0.5Zn-0.5Zr and Mg-12Gd-0.5Zn-0.5Zr alloys always exhibit a lower elongation.