Effects of Sb Addition on Microstructure and Mechanical Properties of Mg-4Al-4Si Magnesium Alloy

The effects of Sb on the microstructure and mechanical properties of Mg-4Al-4Si (AS44) alloys were studied.The results show that the microstructure of as-cast AS44 alloy consists of α-Mg matrix,β-Mg17Al12 phase and Mg2Si phase before adding Sb.The phase Mg2Si exists in three different morphologies,namely the coarse skeleton-like,massive and the Chinese script type.The Mg2Si phase particles can obviously be refined after adding (0.25 wt%-1.25 wt%)Sb in Mg-4Al-4Si alloy,as well as a new phase with high melting-point Mg3Sb2 is formed,which is dispersed in the matrix.The morphology of Mg2Si particle in as-cast AS44 alloy changes from coarse skeleton-like to fine Chinese script-like mostly with the increase of the content of Sb up to 1.25%.The ultimate tensile strength,yield strength and elongation are also increased by refine microstructures.