Preparation of Mg-15%Al-5%Si-0.5%Sb alloy and its microstructure

The master alloys Mg-2.19%Si and Al-17.8%Si and the in-situ composite Mg-15%Al-5% Si-0.5%Sb were prepared by the permanent mould gravity casting. The experimental results show that Mg-2.19%Si master alloy can fabricated by using 4 mm diameter silicon at 810°C, hold for 5hrs under the protection of gas and covering flux. Al-17.8% Si master alloy could be made by the hypothermia silicon adding method. The Sb in the in-situ composite Mg-15%Al-5%Si-0.5%Sb could refine the Mg₂Si phase and change dendritic Mg₂Si into granular shape, but its refining effect is limited and other measures should be taken to refine structure further.