The influence of lanthanum（Y）content on microstructure and mechanical properties of the as-cast and extruded Mg-Zn-Y alloys was investigated systematically.By casting and extruding Mg-Zn-Zr-Y alloys with different Y contents and performing metallographic microscopic analysis

it is found that Y can change the composition

morphology and distribution of the second phase in the magnesium alloy

and refine the grain size.Meanwhile

the mechanical properties of Mg-Zn-Zr-Y alloy were measured.The results reveal that the W phase of the ternary compound introduced by Y is broken and dispersed in the alloy during hot extrusion process

so that the alloy finally obtains a fine grain structure with a size of 5～7μm

greatly improving the mechanical properties of the magnesium alloy.