The microstructure

mechanical properties and fracture behaviors of Mg-6Zn-1.5Cu alloy at ascast

solution and aging treatment were investigated by OM

SEM

TEM

XRD and mechanical tests

respectively.The experimental results indicate that the microstructure of the as-cast alloy is composed ofα-Mg

semi-continuously or continuously distributed intermetallics（α-Mg+MgZn

2

+Mg

2

Cu+CuZnMg）at grain boundaries and isolated particles in the grain.With the increase of holding time

solution effects and aging strengthening effects of the alloy are increased gradually with solution treatment at 450℃ for 12

20

28 and 36 h

and then aged at 180℃ for 12

20

28 and 36 h.With the solution and aging time more than 28 h

residual eutectic compounds and aging strengthening precipitation present coarsening phenomenon.With aged at 180℃ for 28 h

the alloy with desirable structure presents tensile strength and elongation of 265 MPa and 15.90%

respectively.The fracture morphology of the as-cast alloy is characterized by cleavage and inter-granular fracture

while the fracture behavior of the alloy aged is dominated by the mixture of inter-granular and trans-granular modes.