Microstructure and Mechanical Properties of As-cast Mg-4Al-4Si-0.75Sb Magnesium Alloy

Mg-4Al-4Si-0.75Sb(AS44-0.75Sb)(mass fraction/%) magnesium alloys were prepared by the gravity casting.Microstructure and mechanical properties at room temperature of the as-cast AS44-0.75Sb alloy were investigated.The results show that the as-cast microstructure consists of α-Mg matrix,β-Mg17Al12 phase,Mg2Si phase and Mg3Sb2 phase;the addition Sb of 0.75 results in the formation of Mg3Sb2 phase with high melting-point,the morphology of skeleton-like primary Mg2Si phase can be modified significantly and becomes refinement Chinese script Mg2Si.The hardness HV of alloy is 65.9,yield strength,ultimate tensile strength and extension percentage are about 136.4MPa,172.3MPa and 3.3% respectively.The fracture forms of the alloy is quasi-cleavage brittle fracture.