Microstructure and properties of squeezing casting AZ81 alloy in as-cast（F）

solid solution（T4）and solid solution plus aging（T6）states were investigated by X-ray diffraction（XRD）

optical microscope（OM）

tensile testing and SEM（scanning electron microscope）.The results indicate that

after solid solution

the β-Mg17Al12 phase generated from non-equilibrium solidification is almost fully dissolved into the squeezing casting AZ81 magnesium alloy

meanwhile

tensile fracture morphology is characterized by ductile dimples with various size

and the plastic properties of the alloy are distinctly improved as a result of plastic fracture increase.In addition

tensile strength and elongation of the alloy after solid solution treatment reach 253.81 MPa and 10.24%

respectively

however

macro-hardness and yield strength of the alloy are slightly decreased.After solid solution plus aging

the β-Mg17Al12 phase is continuously precipitated along the grain boundary and along the matrix

which is responsible for the further improvement of tensile strength to 262.49MPa and great increase of macro-hardness and yield strength with the slightly decreasing in elongation.The fracture morphology of the T6 treated alloy is composed of ductile dimples and cleavage facets

characterized by brittle fracture failure.