The effects of electric current pulse on microstructure and mechanical properties of the AZ80-4 Sn magnesium alloy were investigated by pulsed current treatment at different frequencies including 0,300 and 600 Hz in solidification process.The results reveal that the solidification structure of AZ80-4Sn magnesium alloy can be refined and its mechanical properties can be improved by electric pulse treatment.In a certain range,with the increase of pulse frequency,microstructure and properties of the AZ80-4Sn magnesium alloy are improved gradually.Compared with the AZ80-4Sn alloy without pulse treatment,when the AZ80-4Sn alloy is treated by 600 Hz,the coarse dendrite structure is refined with the decrease of the secondary dendrite spacing,meanwhile the larger bulk Mg₂Sn phase is refined and distributed uniformly in the matrix ofα-Mg,where the tensile strength and elongation of the alloy are increased from 101 MPa and 2% to 173 MPa and 2.6%,improved by 71.3% and 30%,respectively.