Microstructure and mechanical properties of die casting Mg-8Zn-3.2Al-0.3Mn-0.7Si-0.06AlP alloy chain saw guide-plate cover in die castings were expounded. The results show that compared with those in gravity casting

the microstructure of the cover in die casting is evidently refined

and tensile strength and elongation is greatly improved. The microstructure of the cover with the improvement of mechanical properties can be greatly refined with AlP modifier addition. The rupture mechanism of the vover both in gravity casting and in die casting is characterized by mixed crack. In addition

the element Si exists as Mg2Si phase in gravity casting while it exists as Mg2Si phase and α-Mg solid solution in die casting.