The hypereutectic Mg-3.2 Si alloy was modified by Mn.Effects of Mn addition on the modification of primary Mg2 Si and mechanical properties of Mg-3.2 Si alloy were investigated.Experimental results show that the primary Mg2 Si can be modified effectively.With 2% Mn addition

the morphology of primary Mg2 Si is changed from equiaxed dendritic to polyhedral.The average particle size of primary Mg2 Si reaches 32μm

decreased by 56.8%

compared with those of the unmodified alloy.The tensile strength and elongation of the modified alloys are increased with Mn addition increase.With 2% Mn addition

the tensile strength and elongation of the Mg-3.2 Si alloy reach 167 MPa and 3.2%

increased by49.1% and by 166.7%

respectively

compared with those of the unmodified alloy.