Microstructures and Properties of Mg-9Al-6Si Magnesium Alloys

Mg-9Al-6Si magnesium alloy samples were prepared using simple gravitycast technology.Microstructure and phase compositions of the as-cast Mg-9Al6Si magnesium alloy were studiee using OM and XRD respectively and tensile properties and hardness at room temperature were tested.The fracture of the alloy was investigated using SEM.Results showed that microstructure of this alloy consists of large prismatic dendritic or blocky primary crystal Mg_2Si and network type of β-Mg_(17)Al_(12) distributed on α-Mg matrix.However Chinese script type Mg_2Si phase was not found in this alloy.The fracture of this alloy at room temperature is brittle fracture mainly consisting of quasi-cleavage-type fracture.The fracture occurs and extends along the interface between α-Mg matrix and Mg_2Si phase.The ultimate tensile strength and hardness of this alloy are 137.45 MPa,123 Hv respectively.