Effects of pulsed magnetic field with different excitation current and magnetic field frequency on structure and properties of Al-12.5Mg-6.7Si Alloy were investigated by scanning electron microscope（SEM）and hardness testing.The results show that with the increase of excitation current and magnetic flux density

primary Mg2Si and eutectic Mg2Si are fined greatly.Comparing with those in gravity field

the primary Mg2Si phase size is decreased by 36%and the hardness is improved slightly.However

primary Mg2Si is coarsened significantly with magnetic field frequency more than 2Hz

and the morphology of eutectic Mg2Si is transformed into needle from dot-like structure

resulting in the decrease of hardness.The pulsed magnetic field with excitation current of 15

1

8Aand magnetic field frequency of 1

2Hz can improve remarkably the microstructures and mechanical properties of the Al-12.5Mg-6.7Si alloy.