Effects of low Si content on the microstructure and properties of Mg-8Zn-4Al-0.3Mn alloy were investigated.It was found that the fluidity and wear resistance of the alloy can be remarkably improved by adding Si

and the grain size can be refined also.The micro-hardness

rigidity

tensile strength and plasticity of the alloy can be obviously increased with Si content lower than 0.41% while can be remarkably decreased due to the occurrence of character Mg

2

Si phase in the alloy with the Si content up to 0.69%

meanwhile

precipitation of τ phase can be restrained and precipitation of φ phase can be promoted resulting from the decrease of Zn

Al atomic fraction in residual liquid phase.